ORCID Profile
0000-0002-4148-2048
Current Organisation
University of Melbourne
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Neurosciences | Sensory Systems | Central Nervous System | Neurobiology | Sensory Processes, Perception And Performance | Sensory Systems | Zoology | Vision Science | Animal Physiology - Systems | Simulation And Modelling | Animal Physiology—Systems | Central Nervous System |
ANZSRC Socio-Economic Objective (SEO)
Biological sciences | Hearing, vision, speech and their disorders | Nervous system and disorders | Nervous System and Disorders | Hearing, Vision, Speech and Their Disorders | Behavioural and cognitive sciences | Energy storage | Expanding Knowledge in the Biological Sciences | Chemical sciences | Mathematical sciences | Other
Related Links
Publications
A review of optimisation strategies used in simultaneous localisation and mapping
Publisher: Informa UK Limited
Date: 29-11-2019
Gating of neuronal responses in macaque primary visual cortex by an attentional spotlight
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 06-1998
DOI: 10.1097/00001756-199806220-00006
Abstract: Neuronal responses were recorded from the striate cortex of monkeys trained to perform visual discrimination at locations in the visual field to which their attention was drawn. A subset of neurons showed vigorous responses to visual stimuli for trials in which the monkey was directing its attention to the respective receptive field location. In trials where attention is directed elsewhere, responses to the same stimuli were significantly reduced. In some cells the early response component was not modulated by attention, but later components were affected by the locus of attention. The results suggest the operation of a feedback in the paradigm that spotlights a topographically restricted area of V1 for further processing at higher levels.
Contrast invariance of orientation tuning in the lateral geniculate nucleus of the feline visual system.
Publisher: Wiley
Date: 06-07-2015
DOI: 10.1111/EJN.12991
Abstract: Responses of most neurons in the primary visual cortex of mammals are markedly selective for stimulus orientation and their orientation tuning does not vary with changes in stimulus contrast. The basis of such contrast invariance of orientation tuning has been shown to be the higher variability in the response for low-contrast stimuli. Neurons in the lateral geniculate nucleus (LGN), which provides the major visual input to the cortex, have also been shown to have higher variability in their response to low-contrast stimuli. Parallel studies have also long established mild degrees of orientation selectivity in LGN and retinal cells. In our study, we show that contrast invariance of orientation tuning is already present in the LGN. In addition, we show that the variability of spike responses of LGN neurons increases at lower stimulus contrasts, especially for non-preferred orientations. We suggest that such contrast- and orientation-sensitive variability not only explains the contrast invariance observed in the LGN but can also underlie the contrast-invariant orientation tuning seen at the level of the primary visual cortex.
Mechanism underpinning the sharpening of orientation and spatial frequency selectivities in the tree shrew (Tupaia belangeri) primary visual cortex
Publisher: Springer Science and Business Media LLC
Date: 03-02-2022
DOI: 10.1007/S00429-021-02445-Y
Abstract: Most neurons in the primary visual cortex (V1) of mammals show sharp orientation selectivity and band-pass spatial frequency tuning. Here, we examine whether sharpening of the broad tuning that exists subcortically, namely in the retina and the lateral geniculate nucleus (LGN), underlie the sharper tuning seen for both the above features in tree shrew V1. Since the transition from poor feature selectivity to sharp tuning occurs entirely within V1 in tree shrews, we examined the orientation selectivity and spatial frequency tuning of neurons within in idual electrode penetrations. We found that most layer 4 and layer 2/3 neurons in the same cortical column preferred the same stimulus orientation. However, a subset of layer 3c neurons close to the layer 4 border preferred near orthogonal orientations, suggesting that layer 2/3 neurons may inherit the orientation preferences of their layer 4 input neurons and also receive cross-orientation inhibition from layer 3c neurons. We also found that layer 4 neurons showed sharper orientation selectivity at higher spatial frequencies, suggesting that attenuation of low spatial frequency responses by spatially broad inhibition acting on layer 4 inputs to layer 2/3 neurons can enhance both orientation and spatial frequency selectivities. However, in a proportion of layer 2/3 neurons, the sharper tuning of layer 2/3 neurons appeared to arise also or even mainly from inhibition specific to high spatial frequencies acting on the layer 4 inputs to layer 2/3. Overall, our results are consistent with the suggestion that in tree shrews, sharp feature selectivity in layer 2/3 can be established by intracortical mechanisms that sharpen biases observed in layer 4, which are in turn inherited presumably from thalamic afferents.
Designing Sparse Reliable Pose-Graph SLAM: A Graph-Theoretic Approach
Publisher: Springer International Publishing
Date: 2016
Optic nerve components may not be equally susceptible to damage by acrylamide
Publisher: Elsevier BV
Date: 11-1981
DOI: 10.1016/0006-8993(81)90877-5
Abstract: Cells in the lateral geniculate nucleus of rats treated with the neurotoxin acrylamide were classified as X or Y according to the criterion of linear summation. Compared with control animals, they had a lower ratio of X to Y cells. It is argued that this effect may be related to differences in axon diameter, the thinner fibres in the optic nerve being more susceptible to damage.
Feature-based visual simultaneous localization and mapping: a survey
Publisher: Springer Science and Business Media LLC
Date: 16-01-2020
Deconstruction waste management through 3D reconstruction and BIM: a case study
Publisher: Springer Science and Business Media LLC
Date: 14-07-2017
DOI: 10.1186/S40327-017-0050-5
Abstract: The construction industry is responsible for 50% of the solid waste generated worldwide. Governments around the world formulate legislation and regulations concerning recycling and re-using building materials, aiming to reduce waste and environmental impact. Researchers have also been developing strategies and models of waste management for construction and demolition of buildings. The application of Building Information Modeling (BIM) is an ex le of this. BIM is emergent technology commonly used to maximize the efficiency of design, construction and maintenance throughout the entire lifecycle. The uses of BIM on deconstruction or demolition are not common especially the fixtures and fittings of buildings are not considered in BIM models. The development of BIM is based on two-dimensional drawings or sketches, which may not be accurately converted to 3D BIM models. In addition, previous researches mainly focused on construction waste management. There are few studies about the deconstruction waste management focusing on demolition. To fill this gap, this paper aims to develop a framework using a reconstructed 3D model with BIM, for the purpose of improving BIM accuracy and thus developing a deconstruction waste management system to improve demolition efficiency, effective recycling and cost savings. In particular, the developed as-built BIM will be used to identify and measure recyclable materials, as well as to develop a plan for the recycling process.
Description of stability for linear time‐invariant systems based on the first curvature
Publisher: Wiley
Date: 14-11-2019
DOI: 10.1002/MMA.5896
An Invariant-EKF VINS Algorithm for Improving Consistency
Publisher: arXiv
Date: 2017
Primary visual cortex and memory: Retinal position specificity and lack of size constancy at early stages of learning a visual memory task in the macaque
Publisher: Springer Science and Business Media LLC
Date: 10-2001
Abstract: Two monkeys were trained in a novel version of a delayed match-to-s le (DMS) task. They were required to fixate on a small spot at the center of the monitor and distinguish whether two gratings presented one after the other with delays up to 1.5 s in a specific visual field location were similar or not. It was found that such learning fails to transfer readily to other retinal locations. In fact, the learning was sensitive even to very small retinal displacements of the visual stimuli. Such acute retinal position specificity implies that at least a component of the learning in this particular memory task occurs at an early visual area such as the striate cortex, which has a fine-grain topographical representation. Furthermore, at early stages of learning the DMS task, when the monkeys had not generalized the learning to stimuli of different sizes, they failed to show size constancy. That is, when the display was placed at a different distance but with the same absolute size, the performance dropped. The performance was almost fully restored when, at the new display location, stimuli were changed to fit the original retinal size. This indicates that a crucial component of the learning does occur at a site even prior to size constancy. These results show that, under certain situations, an early visual area such as the primary visual cortex may be involved even in complex behaviours such as a memory task as more than just a feature-detecting area or a relay station.
Dyslexia: a deficit in visuo-spatial attention, not in phonological processing
Publisher: Elsevier BV
Date: 02-2010
DOI: 10.1016/J.TICS.2009.12.003
Abstract: Developmental dyslexia affects up to 10 per cent of the population and it is important to understand its causes. It is widely assumed that phonological deficits, that is, deficits in how words are sounded out, cause the reading difficulties in dyslexia. However, there is emerging evidence that phonological problems and the reading impairment both arise from poor visual (i.e., orthographic) coding. We argue that attentional mechanisms controlled by the dorsal visual stream help in serial scanning of letters and any deficits in this process will cause a cascade of effects, including impairments in visual processing of graphemes, their translation into phonemes and the development of phonemic awareness. This view of dyslexia localizes the core deficit within the visual system and paves the way for new strategies for early diagnosis and treatment.
Perceptual learning in seeing form from motion
Publisher: The Royal Society
Date: 22-12-1993
Abstract: Some perceptual tasks, such as global stereopsis, have been shown to improve with practice. Paradigms that involve such 'perceptual learning' have been exploited to learn more about the nature and sites of these perceptual tasks in the brain and about plasticity in the adult central nervous system. We found that seeing structure from global motion in some kinematograms composed of tilted line elements required a period of learning. However, such learning was specific neither to the orientation of the line elements nor to the direction of global motion, even though detection of these line elements and the direction of motion was necessary for seeing the global structure in these kinematograms. Our results suggest that the neural site of deriving form from motion is beyond the level of in idual motion and pattern detectors. In both its nature and locus along the hierarchy of the visual system, this learning is quite different from other types of perceptual learning reported so far.
A 16bit 1MS/s High-Bit Sampling SAR ADC with Improved Binary-Weighted Capacitive Array
Publisher: IEEE
Date: 23-10-2020
A new feature parametrization for monocular SLAM using line features
Publisher: Cambridge University Press (CUP)
Date: 05-03-2015
DOI: 10.1017/S026357471400040X
Abstract: This paper presents a new monocular SLAM algorithm that uses straight lines extracted from images to represent the environment. A line is parametrized by two pairs of azimuth and elevation angles together with the two corresponding camera centres as anchors making the feature initialization relatively straightforward. There is no redundancy in the state vector as this is a minimal representation. A bundle adjustment (BA) algorithm that minimizes the reprojection error of the line features is developed for solving the monocular SLAM problem with only line features. A new map joining algorithm which can automatically optimize the relative scales of the local maps is used to combine the local maps generated using BA. Results from both simulations and experimental datasets are used to demonstrate the accuracy and consistency of the proposed BA and map joining algorithms.
Greenhouse cure
Publisher: Springer Science and Business Media LLC
Date: 10-1986
DOI: 10.1038/323390B0
Possible plasticity in the rat superior colliculus [20]
Publisher: Springer Science and Business Media LLC
Date: 09-1978
DOI: 10.1038/275140A0
Conic Feature Based Simultaneous Localization and Mapping in Open Environment via 2D Lidar
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2019
A minimally invasive and reversible system for chronic recordings from multiple brain sites in macaque monkeys
Publisher: Elsevier BV
Date: 07-2009
DOI: 10.1016/J.JNEUMETH.2009.04.024
Abstract: We have developed a reversible system for performing simultaneous recordings from multiple brain areas of trained macaque monkeys. It consists of a near-circular halo fitted around the head of the monkey with 5-10 thin plastic or stainless steel posts that either jut against or are screwed into the skull, respectively. Both methods of implantation of the posts are easily reversible, enabling protracted recordings over many years and training the monkeys in more complex tasks. The former is more useful for shorter periods of recordings (2-4 months) separated by long intervals and the latter for longer periods of recordings at a time (6-12 months). With both systems, essentially the entire scalp is intact, allowing multi-site recordings from a number of dorsal cortical areas, as well as other areas, simultaneously. These recordings are performed through tiny craniotomies of usually less than 2mm diameter, which are fitted with small plastic cones that serve as guide tubes for the microelectrodes. The surgery involved in these procedures is relatively minor compared to classical methods and the implants are also usually free of infections, thus requiring little maintenance of recording chambers.
Fast, On-board, Model-aided Visual-Inertial Odometry System for Quadrotor Micro Aerial Vehicles
Publisher: arXiv
Date: 2016
Postsynaptic potentials in cat visual cortex: Dependence on polarization
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-1992
DOI: 10.1097/00001756-199208000-00006
Abstract: During the investigation of visually evoked postsynaptic potentials (PSPs) of visual cortical neurons, we recorded cell activity under different levels of membrane potential. In some cases, however, dependence of these PSPs on the level of membrane polarization appears to be inconsistent with the conventional scheme. One disagreement was the reduction, instead of an increase, of excitatory potentials during hyperpolarization of the cell. The other point was that depolarization of the cell often leads to increase of the litude of both excitatory and inhibitory postsynaptic potentials. This inconsistency may suggest the involvement of voltage-dependent ion channels in generating PSPs to visual stimuli. A possible way of separating the excitatory and inhibitory components of the response by polarization of the cell in spite of the presence of voltage-dependent channels and possible implications of this mechanism in the visual cortex are discussed.
Convergence and Consistency Analysis for A 3D Invariant-EKF SLAM
Publisher: arXiv
Date: 2017
MACAQUE STRIATE CORTEX: PATTERN, MOVEMENT AND COLOUR PROCESSING
Publisher: Wiley
Date: 1984
Relationship between orientation tuning and spatial frequency in neurones of cat area 17
Publisher: Springer Science and Business Media LLC
Date: 02-1985
DOI: 10.1007/BF00237851
Abstract: Tissue phase velocity mapping (TPVM) is capable of reproducibly measuring regional myocardial velocities. However acquisition durations of navigator gated techniques are long and unpredictable while current breath-hold techniques have low temporal resolution. This study presents a spiral TPVM technique which acquires high resolution data within a clinically acceptable breath-hold duration. Ten healthy volunteers are scanned using a spiral sequence with temporal resolution of 24 ms and spatial resolution of 1.7 × 1.7 mm. Retrospective cardiac gating is used to acquire data over the entire cardiac cycle. The acquisition is accelerated by factors of 2 and 3 by use of non-Cartesian SENSE implemented on the Gadgetron GPU system resulting in breath-holds of 17 and 13 heartbeats, respectively. Systolic, early diastolic, and atrial systolic global and regional longitudinal, circumferential, and radial velocities are determined. Global and regional velocities agree well with those previously reported. The two acceleration factors show no significant differences for any quantitative parameter and the results also closely match previously acquired higher spatial resolution navigator-gated data in the same subjects. By using spiral trajectories and non-Cartesian SENSE high resolution, TPVM data can be acquired within a clinically acceptable breath-hold.
Decentralised Mission Monitoring with Spatiotemporal Optimal Stopping
Publisher: IEEE
Date: 10-2018
Eccentricity dependence of orientation anisotropy of surround suppression of contrast-detection threshold
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 09-07-2018
DOI: 10.1167/18.7.5
Abstract: Both neurophysiological and psychophysical data provide evidence for orientation biases in nonfoveal vision-specifically, a tendency for a Cartesian horizontal and vertical bias close to fixation, changing to a radial bias with increasing retinal eccentricity. We explore whether the strength of surround suppression of contrast detection also depends on retinotopic location and relative surround configuration (horizontal, vertical, radial, tangential) in parafoveal vision. Three visual-field locations were tested (0°, 225°, and 270°, angle increasing anticlockwise from 0° horizontal axis) at viewing eccentricities of 6° and 15°. Contrast-detection threshold was estimated with and without a surrounding annulus. At 6° eccentricity, horizontally oriented parallel center-surround (C-S) configurations resulted in greater surround suppression compared to vertically oriented parallel center-surround configurations (p = 0.001). At 15° eccentricity, radially oriented parallel center-surround stimuli conferred greater suppression than tangentially oriented stimuli (p = 0.027). Parallel surrounds resulted in greater suppression than orthogonal surrounds at both eccentricities (p < 0.05). At 6° the horizontal center was more susceptible to suppression than a vertical center (p < 0.001) for both parallel and orthogonal surrounds, while at 15° a radial center was more susceptible to suppression (relative to a tangential center), but only if the surround was parallel (p = 0.005). Our data show that orientation anisotropy of surround suppression alters with eccentricity, reflecting a link between suppression strength and visual-field retinotopy.
Linear SFM: A Hierarchical Approach to Solving Structure-from-Motion Problems by Decoupling the Linear and Nonlinear Components
Publisher: Elsevier BV
Date: 07-2015
Functional comparison of neuronal properties in the primate posterior hippocampus and parahippocampus (area TF/TH) during different behavioural paradigms involving memory and selective attention
Publisher: Elsevier BV
Date: 02-1993
DOI: 10.1016/S0166-4328(05)80273-6
Abstract: Monkeys were trained on a delayed match-to-s le (DMS) task. In addition a standardized behavioural trial was performed which involved an experimenter approaching the animal in certain sequence and presenting edible or other objects ('raisin trial'). Neuronal activity of 617 units was recorded in the posterior parahippoc us (PH) and in the posterior hippoc us (H). In many cases, we compared the activity of the same neuron in different tasks. 32.7% of the 455 PH neurons and 28.5% of the 130 H cells responded during the presentation of the visual stimuli in the DMS task. These responses were only mildly influenced by the physical dimensions of the visual stimulus, but often depended on the context in which the stimuli were presented. There was no differential response to the second stimulus that clearly depended on the nature of the first stimulus. 6.2% of the PH units, but none in H, responded in relation to the reward. 4.4% of the PH neurons, but none in H, showed a mild response during the interstimulus interval. 38.1% of 215 PH neurons and 37.8% of 45 H cells responded during one or more phases of the raisin trial. These responses were not related to the physical dimensions of the sensory stimuli. 210 PH and 41 H units were investigated during the DMS task as well as during the raisin trial. 18.1% (PH) and 12.2% (H) of the units responded during the DMS task, but not during the raisin trial 17.1% (PH) and 36.6% (H) responded vice versa. A response in both trials was found in 17.1% of the PH neurons, but in none of the H cells. There were also other PH unit types showing responses during different aspects of the DMS task and even in other control paradigms, while no such overlap was encountered in H. Our results suggest a function of H and PH in the evaluation of the behavioural significance of sensory information. It may be this aspect which leads to anterograde memory disturbances after lesion of these areas. Since representation of neuronal information was found to be more specific in H, a possible function as an 'evaluation index' is discussed.
Subcortical orientation biases explain orientation selectivity of visual cortical cells.
Publisher: Wiley
Date: 04-2015
DOI: 10.14814/PHY2.12374
Visual attention and neural oscillations in reading and dyslexia: Are they possible targets for remediation?
Publisher: Elsevier BV
Date: 07-2019
DOI: 10.1016/J.NEUROPSYCHOLOGIA.2019.02.009
Abstract: After decades of finding a range of cognitive functions both in visual and phonological domains that correlate with reading performance, there are in recent years attempts to solve the causation versus correlation dilemma in finding a core deficit in developmental dyslexia (DD). Thus, longitudinal studies that aim to predict reading difficulties from studies done in pre-reading years and reading-level matched studies that try to factor out the effect due to lack of reading in DD cohorts, have helped identify two possible candidates to be added to the classical phonological suspect. One is a deficit in visuo-spatial attention that underpins our ability to selectively attend to in idual objects in a cluttered world, which is fundamental in being able to identify letters and words in a text such as the one you are reading now. The other is an impairment in synchronised neuronal oscillations that may be crucial in mediating many cortical functions and also communication between brain regions. The latter may be a general deficit affecting many areas of the brain and thus underlie the wide-ranging co-morbidities in DD. However, that neuronal synchrony is a critical mediator in visual attention, brings the two suggestions into one hypothesis of a core deficit that triggers in some young children a great reluctance to read, putting them at a handicap in comparison to other children. This deprives them of the advantage that normal readers have in development of those visual and phonological processes that are needed for reading. This insight into aetiology may help in developing new remediation strategies, specifically aimed at improving visual attention and neuronal synchrony.
Orientation sensitivity of cat LGN neurones with and without inputs from visual cortical areas 17 and 18
Publisher: Springer Science and Business Media LLC
Date: 05-1982
DOI: 10.1007/BF00237172
Abstract: Interferon-gamma receptor deficiency is a recently described immunodeficiency that is associated with onset of severe mycobacterial infections in childhood. We describe the occurrence of symptomatic and often severe viral infections in 4 patients with interferon-gamma receptor deficiency and mycobacterial disease. The viral pathogens included herpes viruses, parainfluenza virus type 3, and respiratory syncytial virus. We conclude that patients with interferon-gamma receptor deficiency and mycobacterial disease have increased susceptibility to some viral pathogens.
IN2LAAMA: INertial Lidar Localisation Autocalibration And MApping
Publisher: arXiv
Date: 2019
Tracking blue cone signals in the primate brain
Publisher: Informa UK Limited
Date: 05-2013
DOI: 10.1111/J.1444-0938.2012.00819.X
Abstract: In this paper, we review the path taken by signals originating from the short wavelength sensitive cones (S-cones) in Old World and New World primates. Two types of retinal ganglion cells (RGCs) carrying S-cone signals (blue-On and blue-Off cells) project to the dorsal lateral geniculate nucleus (dLGN) in the thalamus. In all primates, these S-cone signals are relayed through the 'dust-like' (konis in classical Greek) dLGN cells. In New World primates such as common marmoset, these very small cells are known to form distinct and spatially extensive, koniocellular layers. Although in Old World primates, such as macaques, koniocellular layers tend to be very thin, the adjacent parvocellular layers contain distinct koniocellular extensions. It appears that all S-cone signals are relayed through such konio cells, whether they are in the main koniocellular layers or in their colonies within the parvocellular layers of the dLGN. In the primary visual cortex, these signals begin to merge with the signals carried by the other two principal parallel channels, namely the magnocellular and parvocellular channels. This article will also review the possible routes taken by the S-cone signals to reach one of the topographically organised extrastriate visual cortical areas, the middle temporal area (area MT). This area is the major conduit for signals reaching the parietal cortex. Alternative visual inputs to area MT not relayed via the primary visual cortex area (V1) may provide the neurological basis for the phenomenon of 'blindsight' observed in human and non-human primates, who have partial or complete damage to the primary visual cortex. Short wavelength sensitive cone (S-cone) signals to area MT may also play a role in directing visual attention with possible implications for understanding the pathology in dyslexia and some of its treatment options.
A neuronal model of attentional spotlight: Parietal guiding the temporal
Publisher: Elsevier BV
Date: 07-1999
DOI: 10.1016/S0165-0173(99)00005-3
Abstract: Recent studies have reported an attentional feedback that highlights neural responses as early along the visual pathway as the primary visual cortex. Such filtering would help in reducing informational overload and in performing serial visual search by directing attention to in idual locations in the visual field. The magnocellular (M) and parvocellular (P) sub isions are two of the major parallel pathways in primate vision that originate in the retina and carry distinctly different types of information. The M pathway, characterized by its high sensitivity to movement and to low contrast stimuli, forms the predominant visual input into the dorsal, parietal stream in the neocortex. The P inputs, characterized by their colour selectivity and higher spatial resolution, are channeled mainly into the ventral, temporal stream. It is proposed that the attentional spotlight originates in the dorsal stream and helps in serially searching the field for conjunction of the relevant target features in the temporal stream, effectively performing a gating function on all visual inputs. This model predicts that a defect limited to the magnocellular or the dorsal pathway can lead to widespread deficits in cognitive abilities, including those functions that are largely based on parvocellular information. For ex le, the model provides a neural mechanism linking a peripheral defect in the magnocellular pathway to the reading disabilities in dyslexia. Even though there has been strong evidence for a magnocellular deficit in dyslexia, the paradox has been that the cognitive disability seems to be related to P pathway function. The scheme proposed here shows how M input may be vital for controlling sequential attention during reading.
Role of feedforward geniculate inputs in the generation of orientation selectivity in the cat's primary visual cortex
Publisher: Wiley
Date: 27-04-2011
Assessment of Brain Electrical Activity in Relation to Memory and Complex Behavior
Publisher: Elsevier
Date: 1993
Linear SLAM: Linearising the SLAM problems using submap joining
Publisher: Elsevier BV
Date: 02-2019
Letter-order encoding is both bottom-up and top-down: Response to Whitney
Publisher: Elsevier BV
Date: 06-2010
Modulation of neuronal responses in macaque primary visual cortex in a memory task
Publisher: Wiley
Date: 16-04-2007
DOI: 10.1111/J.1460-9568.2007.05483.X
Abstract: The primary visual cortex, a relatively early station in the visual pathway, has long been considered mainly as a site of basic feature detection but evidence is emerging that is consistent with the existence of feedback influences from higher cortical areas. We show that in a delayed match-to-s le memory task, where the monkey needs to remember both the visual pattern and its location, there is significant modulation of neuronal activity in the primary visual cortex suggestive of a feedback signal. Responses to identical patterns are remarkably different depending upon their place in the memory task. These modulatory influences are significantly less when the same visual patterns are shown during a simple fixation task, where these stimuli can be ignored and not attended to. The results indicate that neural processing specific to attentional and mnemonic functions can involve even primary sensory areas.
A pose pruning driven solution to pose feature GraphSLAM
Publisher: Informa UK Limited
Date: 26-01-2015
Impaired visual search in dyslexia relates to the role of the magnocellular pathway in attention
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 04-1999
DOI: 10.1097/00001756-199904260-00024
Abstract: We tested the hypothesis that in a cluttered visual scene, the magnocellular (M) pathway is crucial for focusing attention serially on the objects in the field. Since developmental dyslexia is commonly associated with an M pathway deficit, we compared reading impaired children and age-matched normal readers in a search task that required the detection of a target defined by the conjunction of two features, namely form and colour, that are processed by the parvocellular dominated ventral neocortical stream. The dyslexic group's performance was significantly poorer than the controls when there were a large number of distractor items. The scheme of selective attention proposed from these results provides a neural mechanism that underlies reading and explains the pathophysiology of dyslexia.
A Method of State Estimation for Underwater Vehicle Navigation Around A Cylindrical Structure
Publisher: IEEE
Date: 06-2016
L2-SIFT: SIFT feature extraction and matching for large images in large-scale aerial photogrammetry
Publisher: Elsevier BV
Date: 05-2014
Motion segmentation based robust RGB-D SLAM
Publisher: IEEE
Date: 06-2015
An observable time series based SLAM algorithm for deforming environment
Publisher: arXiv
Date: 2019
Parallax Bundle Adjustment on Manifold with Improved Global Initialization
Publisher: Springer International Publishing
Date: 2018
An Automatic Slope-Calibrated Ramp Generator for Single-Slope ADCs
Publisher: IEEE
Date: 10-2019
Orientation specific colour adaptation at a binocular site
Publisher: Springer Science and Business Media LLC
Date: 05-1976
DOI: 10.1038/261039A0
Convergence of parvocellular and magnocellular information channels in the primary visual cortex of the macaque
Publisher: Wiley
Date: 09-2002
DOI: 10.1046/J.1460-9568.2002.02137.X
Abstract: We investigated whether responses of single cells in the striate cortex of anaesthetized macaque monkeys exhibit signatures of both parvocellular (P) and magnocellular (M) inputs from the dorsal lateral geniculate nucleus (dLGN). We used a palette of 128 isoluminant hues at four different saturation levels to test responses to chromatic stimuli against a white background. Spectral selectivity with these isoluminant stimuli was taken as an indication of P inputs. The presence of magnocellular inputs to a given cortical cell was deduced from its responses to a battery of tests, including assessment of achromatic contrast sensitivity, relative strengths of chromatic and luminance borders in driving the cell at different velocities and conduction velocity of their retino-geniculo-cortical afferents. At least a quarter of the cells in our cortical s le appear to receive convergent P and M inputs. We cannot however, exclude the possibility that some of these cells could be receiving a convergent input from the third parallel channel from the dLGN, namely the koniocellular (K) rather than the P channel. The neurons with convergent P and M inputs were recorded not only from supragranular and infragranular layers but also from the principal geniculate input recipient layer 4. Thus, our results challenge classical ideas of strict parallelism between different information streams at the level of the primate striate cortex.
The fate of the Taj Mahal [1]
Publisher: Springer Science and Business Media LLC
Date: 11-1978
DOI: 10.1038/276208A0
Multiple pathways carry signals from short-wavelength-sensitive ('blue') cones to the middle temporal area of the macaque
Publisher: Wiley
Date: 21-11-2013
Surface segregation influences pre-attentive search in depth
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-2004
DOI: 10.1097/00001756-200402090-00018
Abstract: While searching for an object in a cluttered scene, in some situations, the visual system adopts a pre-attentive parallel search, where the time taken is independent of the number of items in the scene. In others, the search is serial, time taken being a function of the set size. We show that detecting the number of targets (2, 3 or 4) that differ in depth from background items is a parallel process, but only when they are all in the same surface in depth. The search is serial if the targets are in different depth planes, but parallel even if the targets were on a surface tilted in depth, showing that surface segregation influences a parallel, apparently pre-attentive, stage.
The role of the magnocellular pathway in serial deployment of visual attention
Publisher: Wiley
Date: 10-2004
A model of striate response properties based on geniculate anisotropies
Publisher: Springer Science and Business Media LLC
Date: 08-1987
DOI: 10.1007/BF00318712
Abstract: Since the 1980s, advances in wastewater treatment technology have led to considerably improved surface water quality in the urban areas of many high income countries. However, trace concentrations of organic wastewater-associated contaminants may still pose a key environmental hazard impairing the ecological quality of surface waters. To identify key impact factors, we analyzed the effects of a wide range of anthropogenic and environmental variables on the aquatic macroinvertebrate community. We assessed ecological water quality at 26 s ling sites in four urban German lowland river systems with a 0-100% load of state-of-the-art biological activated sludge treated wastewater. The chemical analysis suite comprised 12 organic contaminants (five phosphor organic flame retardants, two musk fragrances, bisphenol A, nonylphenol, octylphenol, diethyltoluamide, terbutryn), 16 polycyclic aromatic hydrocarbons, and 12 heavy metals. Non-metric multidimensional scaling identified organic contaminants that are mainly wastewater-associated (i.e., phosphor organic flame retardants, musk fragrances, and diethyltoluamide) as a major impact variable on macroinvertebrate species composition. The structural degradation of streams was also identified as a significant factor. Multiple linear regression models revealed a significant impact of organic contaminants on invertebrate populations, in particular on Ephemeroptera, Plecoptera, and Trichoptera species. Spearman rank correlation analyses confirmed wastewater-associated organic contaminants as the most significant variable negatively impacting the bio ersity of sensitive macroinvertebrate species. In addition to increased aquatic pollution with organic contaminants, a greater wastewater fraction was accompanied by a slight decrease in oxygen concentration and an increase in salinity. This study highlights the importance of reducing the wastewater-associated impact on surface waters. For aquatic ecosystems in urban areas this would lead to: (i) improvement of the ecological integrity, (ii) reduction of bio ersity loss, and (iii) faster achievement of objectives of legislative requirements, e.g., the European Water Framework Directive.
Pattern adaptation in cat visual cortex is a co-operative phenomenon
Publisher: Elsevier BV
Date: 1990
DOI: 10.1016/0306-4522(90)90360-G
Abstract: The effects of microiontophoretic application of glutamate, GABA and the GABA antagonist, bicuculline methiodide were tested on the degree of adaptation exhibited by striate cortical cells to moving sin wave grating patterns. Application of GABA, which prevents firing of the cell and thereby any fatigue of the cell, did not reduce the degree of adaptation. Administration of either glutamate or GABA, without simultaneous exposure to the adapting high-contrast gratings did not reduce the sensitivity of the cell to subsequent exposure of a low-contrast grating, showing that adaptation is not caused by the excitatory or inhibitory activity of the cell itself. Application of the GABA antagonist, bicuculline did not prevent pattern adaptation, indicating that the lowered sensitivity of the cell is not mediated by a GABAergic inhibition acting on the cell. Thus adaptation of a striate neuron is not due to altered sensitivity of the cell to a constant input but depends upon changes in the input itself. It is most likely that these changes occur in a co-operative cortical network, whose effect on in idual cortical cells is mediated by intracortical excitatory connections.
Aetiology of Dyslexia: A Visual Perspective on a Phonological Marker
Publisher: Oxford University Press
Date: 23-08-2003
Relationship between preferred orientation and ordinal position in neurones of cat striate cortex
Publisher: Cambridge University Press (CUP)
Date: 12-1990
DOI: 10.1017/S0952523800000729
Abstract: Striate cortical cells were classified according to whether or not their preferred orientation was close to one of the “primary” orientations (horizontal, vertical or radial, i.e. directed to the area centralis) and according to their ordinal position on the afferent pathway from the dorsal lateral geniculate nucleus (dLGN). Among the neurones that could be driven monosynaptically from the dLGN, there was a high representation of those with a preference for the primary orientations. This was particularly evident in the case of C (complex) cells. There was no such preponderance of primary orientations among the polysynaptically activated cells. It is proposed that the asymmetry of distribution seen among the first-order cells reflects the asymmetry seen subcortically in neurones that show orientation biases. It may be that the cortex elaborates a more uniform representation of orientations only at the higher ordinal levels.
Neural spike irregularity in adjacent cells of the same visual cortical column are unrelated despite other shared properties
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 15-03-2002
DOI: 10.1167/2.7.110
Online Estimation of Ocean Current from Sparse GPS Data for Underwater Vehicles
Publisher: arXiv
Date: 2019
Attentional gating in primary visual cortex: A physiological basis for dyslexia
Publisher: SAGE Publications
Date: 08-2005
DOI: 10.1068/P5332
Abstract: The visual magnocellular pathway is known to play a central part in visuospatial attention and in directing attention to specific parts of the visual world in serial search. It is proposed that, in the case of reading, this mechanism is trained to perform a sequential gating of visual information coming into the primary visual cortex to enable further orderly processing by the ventral stream. This scheme, taken together with the potential for plasticity between the different afferent channels in the case of a relative impairment of the magnocellular system, can provide some limited rationale for the beneficial effects that have been claimed for the use of coloured overlays and glasses.
The responses of cells in macaque lateral geniculate nucleus to sinusoidal gratings.
Publisher: Wiley
Date: 04-1983
DOI: 10.1113/JPHYSIOL.1983.SP014619
Abstract: Responses of cells in the parvocellular (p.c.l.) and magnocellular (m.c.l.) layers of the macaque lateral geniculate nucleus to sine-wave gratings were studied. Both p.c.l. and m.c.l. cells responded best at a temporal frequency (drift rate) of 10-20 Hz. P.c.l. cells responded at temporal frequencies lower than 1 Hz m.c.l. cells did not. With coloured- or white-black luminance-modulated gratings, responses of m.c.l. cells were weaker at low than at medium spatial frequencies. With coloured gratings, p.c.l. cell responses were not attenuated at low spatial frequencies. With white gratings a few p.c.l. cells did show such attenuation. Optimal responses from p.c.l. cells were obtained with coloured gratings white gratings evoked weaker responses. With a grating of a colour causing suppression of a p.c.l. cell's activity, the modulation of firing was much less than with a grating of a colour excitatory for the cell. M.c.l. on- and off-centre cells responded equally well to moving gratings. The ability of p.c.l. cells to resolve fine gratings was dependent on cell type as well as on the colour of grating used. The ability of m.c.l. cells to resolve fine gratings was comparable to that of p.c.l. cells. The contrast sensitivity of m.c.l. cells was much higher than that of p.c.l. cells. This may account for their ability to resolve fine gratings, despite their larger centre size. In comparison with luminance-modulated gratings, chromatically modulated gratings could evoke larger or smaller responses, depending on p.c.l. cell type and the colours in the grating. M.c.l. cells responded poorly or not at all.
Exploiting the separable structure of SLAM
Publisher: Robotics: Science and Systems Foundation
Date: 13-07-2015
Origins of feature selectivities and maps in the mammalian primary visual cortex
Publisher: Elsevier BV
Date: 08-2015
DOI: 10.1016/J.TINS.2015.06.003
Abstract: A common feature of the mammalian striate cortex is the arrangement of 'orientation domains' containing neurons preferring similar stimulus orientations. They are arranged as spokes of a pinwheel that converge at singularities known as 'pinwheel centers'. We propose that a cortical network of feedforward and intracortical lateral connections elaborates a full set of optimum orientations from geniculate inputs that show a bias to stimulus orientation and form a set of two or a small number of 'Cartesian' coordinates. Because each geniculate afferent carries signals only from one eye and its receptive field (RF) is either ON or OFF center, the network constructs also ocular dominance columns and a quasi-segregation of ON and OFF responses across the horizontal extent of the striate cortex.
Space, color, and direction of movement: How do they affect attention?
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 19-07-2013
DOI: 10.1167/13.8.20
Abstract: Paying attention improves performance, but is this improvement regardless of what we attend to? We explored the differences in performance between attending to a location and attending to a feature when perceiving global motion. Attention was first cued to one of four locations that had coherently moving dots, while the remaining three had randomly moving distracter dots. Participants then viewed a colored display, wherein the color of the coherently moving dots was cued instead of location. In the third task, participants identified the location that had a particular cued direction of motion. Most observers reported reductions of motion threshold in all three tasks compared to when no cue was provided. However, the attentional bias generated by location cues was significantly larger than the bias resulting from feature cues of direction or color. This effect is consistent with the idea that attention is largely controlled by a fronto-parietal network where spatial relations are preferentially processed. On the other hand, color could not be used as a cue to focus attention and integrate motion. This finding suggests that color relies heavily on processing by ventral temporal cortical areas, which may have little control over the global motion areas in the dorsal part of the brain.
An improved simple tungsten microelectrode
Publisher: Elsevier BV
Date: 03-1979
DOI: 10.1016/0361-9230(79)90293-4
Abstract: An improvement to tungsten-in-glass microelectrode has been made which requires to special skills. It involves the introduction of a gel solution into the glass micropipette which surrounds and binds the tungsten wire along its full length. A significant d ing of microphonic effects is produced and a good fit between tungsten and glass near their tips becomes less critical for success. The electrode was found to be very stable over long recording sessions.
Advanced Control for Singular Systems with Applications
Publisher: Hindawi Limited
Date: 05-06-2018
DOI: 10.1155/2018/1819540
The role of gabaergic inhibition in the response properties of neurones in cat visual area 18
Publisher: Elsevier BV
Date: 1986
DOI: 10.1016/0306-4522(86)90224-1
Abstract: Bicuculline methiodide was iontophoretically applied to single neurones in cat area 18 to investigate how removal of gamma-aminobutyrate mediated inhibition affects the visual response properties. Moving sinusoidal gratings were used to study spatial and temporal response characteristics. Orientation sensitivity and spatial and temporal frequency tuning curves were determined with and without iontophoretically applied bicuculline. In most neurones, orientation sensitivity and spatial frequency tuning remained largely unaffected, whereas temporal frequency tuning was very much broadened. It is suggested that the dominant excitatory input to area 18 cells is a spatially organized input from area 17 and local inhibition in area 18 sharpens primarily temporal selectivity. An alternative explanation of our results would be that the distribution of synapses mediating temporal tuning in area 18 is fundamentally different from that mediating spatial frequency and orientation tuning, which may be located at sites distant from the cell body and relatively inaccessible to the drug application.
A Low-Power Single-Slope based 14-bit Column-Level ADC for 384x288 Uncooled Infrared Imager
Publisher: IEEE
Date: 10-2019
Contribution of inhibitory mechanisms to the orientation sensitivity of cat dLGN neurones
Publisher: Springer Science and Business Media LLC
Date: 05-1984
DOI: 10.1007/BF00240517
Abstract: Comprehensive instrumented muscle and joint assessments should be considered when prescribing Botulinum NeuroToxin-A (BoNT-A) treatment in spastic paresis. In a child with spastic paresis, comprehensive evaluation following treatment with BoNT-A, serial casting, and physiotherapy showed that short-term improvements in gait occurred without changes in muscle morphology. Rather, foot flexibility increased.
Erratum: Convergence of parvocellular and magnocellular information channels in the primary visual cortex of the macaque (European Journal of Neuroscience (2002) 16 (945-956))
Publisher: Wiley
Date: 09-2002
Reading into neuronal oscillations in the visual system: Implications for developmental dyslexia
Publisher: Frontiers Media SA
Date: 2013
A linear model fails to predict orientation selectivity of cells in the cat visual cortex
Publisher: Wiley
Date: 11-1996
DOI: 10.1113/JPHYSIOL.1996.SP021711
Abstract: 1. Postsynaptic potentials (PSPs) evoked by visual stimulation in simple cells in the cat visual cortex were recorded using in vivo whole-cell technique. Responses to small spots of light presented at different positions over the receptive field and responses to elongated bars of different orientations centred on the receptive field were recorded. 2. To test whether a linear model can account for orientation selectivity of cortical neurones, responses to elongated bars were compared with responses predicted by a linear model from the receptive field map obtained from flashing spots. 3. The linear model faithfully predicted the preferred orientation, but not the degree of orientation selectivity or the sharpness of orientation tuning. The ratio of optimal to non-optimal responses was always underestimated by the model. 4. Thus non-linear mechanisms, which can include suppression of non-optimal responses and/or lification of optimal responses, are involved in the generation of orientation selectivity in the primary visual cortex.
An invariant-EKF VINS algorithm for improving consistency
Publisher: IEEE
Date: 09-2017
Parallax Bundle Adjustment on Manifold with Convexified Initialization
Publisher: arXiv
Date: 2018
Cytoarchitecture and visual field representation in area 17 of the tammar wallaby (macropus eugenii)
Publisher: Wiley
Date: 08-11-1992
Abstract: Tritiated proline was injected into one eye in the tammar wallaby and transported label was studied in the cortex after transneuronal passage through the lateral geniculate nucleus. The autoradiographic label and cytoarchitecture were used to anatomically demarcate the borders of area 17. Electrophysiological recordings from single units were done to obtain a retinotopic map of area 17. Single units in area 17 were found to have orientation sensitivity comparable to those seen in placental mammals such as cat and monkey. They could also be classified as simple, complex, and hypercomplex cells. Changes in the cortical areal magnification factor with eccentricity were found to match the drop off in retinal ganglion cell density only along the vertical meridian representation. Along the horizontal meridian, the cortical magnification falls off significantly with eccentricity, whereas the ganglion cell density shows only a mild reduction. Thus central vision, especially the binocular segment, is heavily represented at the cost of the periphery.
Robot Localization: An Introduction
Publisher: Wiley
Date: 15-08-2016
Abstract: Robot localization is the process of determining where a mobile robot is located with respect to its environment. Localization is one of the most fundamental competencies required by an autonomous robot as the knowledge of the robot's own location is an essential precursor to making decisions about future actions. In a typical robot localization scenario, a map of the environment is available and the robot is equipped with sensors that observe the environment as well as monitor its own motion. The localization problem then becomes one of estimating the robot position and orientation within the map using information gathered from these sensors. Robot localization techniques need to be able to deal with noisy observations and generate not only an estimate of the robot location but also a measure of the uncertainty of the location estimate. This article provides an introduction to estimation of theoretic solutions to the robot localization problem. It begins by discussing the mathematical models used to describe the robot motion and observations from the sensors. Two of the most common probabilistic techniques, the extended Kalman filter and the particle filter, that can be used to combine information from sensors to compute an estimate of the robot location are then discussed in detail and illustrated by simple ex les. A brief summary of the large body of literature on robot localization is presented next. Appendices that present the essential mathematical background and alternative techniques are provided. The MATLAB code of the localization algorithms is also available.
High Quality 3D Reconstruction of Indoor Environments using RGB-D Sensors
Publisher: IEEE
Date: 06-2017
Dynamics of coherent activity between cortical areas defines a two-stage process of top-down attention.
Publisher: Springer Science and Business Media LLC
Date: 09-07-2021
Special Issue on Localization and Mapping in Challenging Environments
Publisher: Elsevier BV
Date: 11-2017
Diversity of Feature Selectivity in Macaque Visual Cortex Arising from a Limited Number of Broadly Tuned Input Channels
Publisher: Oxford University Press (OUP)
Date: 10-04-2019
Abstract: Spike (action potential) responses of most primary visual cortical cells in the macaque are sharply tuned for the orientation of a line or an edge, and neurons preferring similar orientations are clustered together in cortical columns. The preferred stimulus orientation of these columns span the full range of orientations, as observed in recordings of spikes and in classical optical imaging of intrinsic signals. However, when we imaged the putative thalamic input to striate cortical cells that can be seen in imaging of intrinsic signals when they are analyzed on a larger spatial scale, we found that the orientation domain map of the primary visual cortex did not show the same ersity of orientations. This map was dominated by just the one orientation that is most commonly preferred by neurons in the retina and the lateral geniculate nucleus. This supports cortical feature selectivity and columnar architecture being built upon feed-forward signals transmitted from the thalamus in a very limited number of broadly tuned input channels.
Reliable Graphs for SLAM
Publisher: SAGE Publications
Date: 22-01-2019
Abstract: Estimation-over-graphs (EoG) is a class of estimation problems that admit a natural graphical representation. Several key problems in robotics and sensor networks, including sensor network localization, synchronization over a group, and simultaneous localization and mapping (SLAM) fall into this category. We pursue two main goals in this work. First, we aim to characterize the impact of the graphical structure of SLAM and related problems on estimation reliability. We draw connections between several notions of graph connectivity and various properties of the underlying estimation problem. In particular, we establish results on the impact of the weighted number of spanning trees on the D-optimality criterion in 2D SLAM. These results enable agents to evaluate estimation reliability based only on the graphical representation of the EoG problem. We then use our findings and study the problem of designing sparse SLAM problems that lead to reliable maximum likelihood estimates through the synthesis of sparse graphs with the maximum weighted tree connectivity. Characterizing graphs with the maximum number of spanning trees is an open problem in general. To tackle this problem, we establish several new theoretical results, including the monotone log-submodularity of the weighted number of spanning trees. We exploit these structures and design a complementary greedy–convex pair of efficient approximation algorithms with provable guarantees. The proposed synthesis framework is applied to various forms of the measurement selection problem in resource-constrained SLAM. Our algorithms and theoretical findings are validated using random graphs, existing and new synthetic SLAM benchmarks, and publicly available real pose-graph SLAM datasets.
A submap joining algorithm for 3D reconstruction using an RGB-D camera based on point and plane features
Publisher: Elsevier BV
Date: 08-2019
On-line 3D active pose-graph SLAM based on key poses using graph topology and sub-maps
Publisher: IEEE
Date: 05-2019
Gaussian process model enabled particle filter for device-free localization
Publisher: IEEE
Date: 07-2017
Eyeing visual pathways in dyslexia
Publisher: American Association for the Advancement of Science (AAAS)
Date: 08-2014
Functional size of human visual area V1: A neural correlate of top–down attention
Publisher: Elsevier BV
Date: 06-2014
DOI: 10.1016/J.NEUROIMAGE.2014.02.023
Abstract: Heavy demands are placed on the brain's attentional capacity when selecting a target item in a cluttered visual scene, or when reading. It is widely accepted that such attentional selection is mediated by top-down signals from higher cortical areas to early visual areas such as the primary visual cortex (V1). Further, it has also been reported that there is considerable variation in the surface area of V1. This variation may impact on either the number or specificity of attentional feedback signals and, thereby, the efficiency of attentional mechanisms. In this study, we investigated whether in idual differences between humans performing attention-demanding tasks can be related to the functional area of V1. We found that those with a larger representation in V1 of the central 12° of the visual field as measured using BOLD signals from fMRI were able to perform a serial search task at a faster rate. In line with recent suggestions of the vital role of visuo-spatial attention in reading, the speed of reading showed a strong positive correlation with the speed of visual search, although it showed little correlation with the size of V1. The results support the idea that the functional size of the primary visual cortex is an important determinant of the efficiency of selective spatial attention for simple tasks, and that the attentional processing required for complex tasks like reading are to a large extent determined by other brain areas and inter-areal connections.
Linear SLAM: Linearising the SLAM Problems using Submap Joining
Publisher: arXiv
Date: 2018
Efficient Active SLAM Based on Submap Joining, Graph Topology and Convex Optimization
Publisher: IEEE
Date: 05-2018
Tree-Connectivity: Evaluating the Graphical Structure of SLAM
Publisher: IEEE
Date: 05-2016
Deep Learning Assisted Automatic Intra-operative 3D Aortic Deformation Reconstruction
Publisher: Springer International Publishing
Date: 2020
Function of GABAA inhibition in specifying spatial frequency and orientation selectivities in cat striate cortex
Publisher: Springer Science and Business Media LLC
Date: 02-1994
DOI: 10.1007/BF00229106
A computational study of how orientation bias in the lateral geniculate nucleus can give rise to orientation selectivity in primary visual cortex
Publisher: Frontiers Media SA
Date: 2011
Integration of the visual and auditory networks in dyslexia: A theoretical perspective
Publisher: Wiley
Date: 08-2005
Dichotomous miR expression and immune responses following primary blood- stage malaria
Publisher: American Society for Clinical Investigation
Date: 03-08-2017
Improvement of the inspection-repair process with building information modelling and image classification
Publisher: Emerald
Date: 07-05-2019
Abstract: Automated technologies have been applied to facility management (FM) practices to address labour demands of, and time consumed by, inputting and processing manual data. Less attention has been focussed on automation of visual information, such as images, when improving timely maintenance decisions. This study aims to develop image classification algorithms to improve information flow in the inspection-repair process through building information modelling (BIM). To improve and automate the inspection-repair process, image classification algorithms were used to connect images with a corresponding image database in a BIM knowledge repository. Quick response (QR) code decoding and Bag of Words were chosen to classify images in the system. Graphical user interfaces (GUIs) were developed to facilitate activity collaboration and communication. A pilot case study in an inspection-repair process was applied to demonstrate the applications of this system. The system developed in this study associates the inspection-repair process with a digital three-dimensional (3D) model, GUIs, a BIM knowledge repository and image classification algorithms. By implementing the proposed application in a case study, the authors found that improvement of the inspection-repair process and automated image classification with a BIM knowledge repository (such as the one developed in this study) can enhance FM practices by increasing productivity and reducing time and costs associated with ecision-making. This study introduces an innovative approach that applies image classification and leverages a BIM knowledge repository to enhance the inspection-repair process in FM practice. The system designed provides automated image-classifying data from a smart phone, eliminates time required to input image data manually and improves communication and collaboration between FM personnel for maintenance in the decision-making process.
Unit activity in the hippocampus and the parahippocampal temporobasal association cortex related to memory and complex behaviour in the awake monkey
Publisher: Elsevier BV
Date: 03-1991
DOI: 10.1016/0006-8993(91)90064-3
Abstract: Monkeys (Macaca fascicularis) were trained on a delayed match-to-s le (DMS) task using delays of upto 20 s. Unit activity was recorded from the hippoc us and the temporo-basal association cortex in the lateral parahippoc al region (partly corresponding to TF and TH) during the DMS task, as well as during a visual object discrimination task and some behavioural situations involving the experimenter. Units were encountered that gave visual responses which were sometimes context-dependent. Changes in discharge rate during the delay period of the DMS task were very rare and when present, very weak. On the other hand, many neurones, including some of those which were unresponsive during the DMS task fired vigorously (or were inhibited) during situations which involved attention, expectation or food consumption. For ex le, the neurones' firing rate was altered when the cage door was opened or closed, the experimenter entered or left the room or showed the monkey a piece of food before giving it to him. A variety of such responses in complex behavioural situations were seen, sometimes even in neurones which did not respond in the DMS task. Activity changes in neurons of the temporo-basal cortex thus appear to be related to the internal state associated with a stimulus and even some of the responses obtained in the DMS task can be interpreted as being related to changes in the behavioural state rather than to the mnemonic elements of the task.
A Submap Joining Based RGB-D SLAM Algorithm using Planes as Features
Publisher: Springer International Publishing
Date: 03-11-2017
Designing Sparse Reliable Pose-Graph SLAM: A Graph-Theoretic Approach
Publisher: arXiv
Date: 2016
Dynamic coupling of oscillatory neural activity and its roles in visual attention
Publisher: Elsevier BV
Date: 04-2022
DOI: 10.1016/J.TINS.2022.01.003
Abstract: Oscillatory neural activity is believed to have a central role in information processing in the mammalian brain. While early studies often focussed on the function of in idual frequency bands, there is emerging appreciation for the role of simultaneous activity in many distinct frequency bands and the interactions between them in high-level cognitive functions. Here, we focus on the role of cross-frequency coupling (CFC) in visual attention. First, we propose a framework that reconciles previous contrasting findings, showing how CFC could have a functional role on both intra- and interareal scales. Second, we outline how CFC between distinct frequency bands could label different submodalities of sensory information. Overall, our scheme provides a novel perspective of how interfrequency interaction contributes to efficient and dynamic processing of information across the brain.
Multiple mechanisms underlying the orientation selectivity of visual cortical neurones
Publisher: Elsevier BV
Date: 07-1996
DOI: 10.1016/S0166-2236(96)20027-X
Abstract: Cheap, rapid, simple and equipment-free nucleic acid extraction (NAE) is highly preferred for implementing nucleic acid detection at point-of-care (POC). Paper-based NAE materials have been extensively utilized due to their low cost, abundance, portability, biocompatibility and ease of chemical modification. However, it is challenging for users to choose the proper one from existing paper-based NAE materials for specific POC applications, which is determined by their physical and chemical properties. Additionally, building the relationship between the physical and chemical properties and the NAE efficiency of paper-based materials is instructive for development of new paper-based NAE materials. In this study, we first systematically compared the physical and chemical properties of six widely used paper-based NAE materials (namely Whatman filter paper #1, FTA card, FTA elute card, Fusion 5, silica membrane and polyethersulfone (PES) membrane), and then evaluated their NAE efficiency. The obtained results indicated that pore uniformity, wet strength, porosity and functional groups are key parameters to affect the efficiency of NAE. The NAE performance of FTA card is the best with high concentration and purity. Finally, we envision that more cost-effective paper-based NAE materials will be developed for POCT application in the future. The online version contains supplementary material available at 10.1007/s10570-022-04444-6.
Sparseness of coding in area 17 of the cat visual cortex: A comparison between pinwheel centres and orientation domains
Publisher: Elsevier BV
Date: 12-2012
DOI: 10.1016/J.NEUROSCIENCE.2012.08.064
Abstract: Optical imaging of intrinsic signals across the primary visual cortex in mammals has shown that neurons tuned to the same stimulus orientation are clustered together to form orientation domains, which converge on singularities called pinwheel centres. We used a combination of two gratings in different mutual relationships as in a plaid to study how visual cortical neurons differ in integrating these signals. Neurons in the centres of orientation domains responded to a smaller range of such composite stimuli than cells near pinwheel centres, even though orientation tuning for a single bar or grating did not differ significantly between the two locations. We believe that this difference between the two locations is related to the way local intracortical interactions generate a full complement of orientation preferences from a limited number of preferred stimulus orientations represented in the geniculate afferents to the striate cortex.
Transmission Dynamics of an SIS Model with Age Structure on Heterogeneous Networks
Publisher: Springer Science and Business Media LLC
Date: 11-06-2018
From attentional gating in macaque primary visual cortex to dyslexia in humans
Publisher: Elsevier
Date: 2001
DOI: 10.1016/S0079-6123(01)34020-7
Abstract: Selective attention is an important aspect of brain function that we need in coping with the immense and constant barrage of sensory information. One model of attention (Feature Integration Theory) that suggests an early selection of spatial locations of objects via an attentional spotlight would also solve the 'binding problem' (that is how do different attributes of each object get correctly bound together?). Our experiments have demonstrated modulation of specific locations of interest at the level of the primary visual cortex both in visual discrimination and memory tasks, where the actual locations of the targets was also important in being able to perform the task. It is suggested that the feedback mediating the modulation arises from the posterior parietal cortex, which would also be consistent with its known role in attentional control. In primates, the magnocellular (M) and parvocellular (P) pathways are the two major streams of inputs from the retina, carrying distinctly different types of information and they remain fairly segregated in their projections to the primary visual cortex and further into the extra-striate regions. The P inputs go mainly into the ventral (temporal) stream, while the dorsal (parietal) stream is dominated by M inputs. A theory of attentional gating is proposed here where the M dominated dorsal stream gates the P inputs into the ventral stream. This framework is used to provide a neural explanation of the processes involved in reading and in learning to read. This scheme also explains how a magnocellular deficit could cause the common reading impairment, dyslexia.
Geniculate orientation biases seen with moving sine wave gratings: implications for a model of simple cell afferent connectivity
Publisher: Springer Science and Business Media LLC
Date: 1984
DOI: 10.1007/BF00231146
Abstract: The reactivities of 2-butyne, cycloheptyne, cyclooctyne, and cyclononyne in the 1,3-dipolar cycloaddition reaction with methyl azide were evaluated through DFT calculations at the M06-2X/6-311++G(d)//M06-2X/6-31+G(d) level of theory. Computed activation free energies for the cycloadditions of cycloalkynes are 16.5-22.0 kcal mol
The effect of aging and attention on visual crowding and surround suppression of perceived contrast threshold
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 03-02-2017
Abstract: The purpose of this study was to study how, in midperipheral vision, aging affects visual processes that interfere with target detection (crowding and surround suppression) and to determine whether the performance on such tasks are related to visuospatial attention as measured by visual search. We investigated the effect of aging on crowding and suppression in detection of a target in peripheral vision, using different types of flanking stimuli. Both thresholds were also obtained while varying the position of the flanker (placed inside or outside of target, relative to fixation). Crowding thresholds were also estimated with spatial uncertainty (jitter). Additionally, we included a visual search task comprising Gabor stimuli to investigate whether performance is related to top-down attention. Twenty young adults (age, 18-32 years mean age, 26.1 years 10 males) and 19 older adults (age, 60-74 years mean age, 70.3 years 10 males) participated in the study. Older adults showed more surround suppression than the young (F[1,37] = 4.21 P < 0.05), but crowding was unaffected by age. In the younger group, the position of the flanker influenced the strength of crowding, but not the strength of suppression (F[1,39] = 4.11 P < 0.05). Crowding was not affected by spatial jitter of the stimuli. Neither crowding nor surround suppression was predicted by attentional efficiency measured in the visual search task. There was also no significant correlation between crowding and surround suppression. We show that aging does not affect visual crowding but does increase surround suppression of contrast, suggesting that crowding and surround suppression may be distinct visual phenomena. Furthermore, strengths of crowding and surround suppression did not correlate with each other nor could they be predicted by efficiency of visual search.
Membrane properties and spike generation in rat visual cortical cells during reversible cooling
Publisher: Wiley
Date: 2000
DOI: 10.1111/J.1469-7793.2000.0059M.X
Abstract: We studied the effects of reversible cooling between 35 and 7 C on membrane properties and spike generation of cells in slices of rat visual cortex. Cooling led to a depolarization of the neurones and an increase of the input resistance, thus bringing the cells closer to spiking threshold. Excitability, measured with intracellular current steps, increased with cooling. Synaptic stimuli were most efficient in producing spikes at room temperature, but strong stimulation could evoke spikes even below 10 C. Spike width and total area increased with cooling, and spike litude was maximal between 12 and 20 C. Repetitive firing was enhanced in some cells by cooling to 20-25 C, but was always suppressed at lower temperatures. With cooling, passive potassium conductance decreased and the voltage-gated potassium current had a higher activation threshold and lower litude. At the same time, neither passive sodium conductance nor the activation threshold of voltage-dependent sodium channels changed. Therefore changing the temperature modifies the ratio between potassium and sodium conductances, and thus alters basic membrane properties. Data from two cells recorded in slices of cat visual cortex suggest a similar temperature dependence of the membrane properties of neocortical neurones to that described above in the rat. These results provide a framework for comparison of the data recorded at different temperatures, but also show the limitations of extending the conclusions drawn from in vitro data obtained at room temperature to physiological temperatures. Further, when cooling is used as an inactivation tool in vivo, it should be taken into account that the mechanism of inactivation is a depolarization block. Only a region cooled below 10 C is reliably silenced, but it is always surrounded by a domain of hyperexcitable cells.
A Temporal Sampling Basis for Visual Processing in Developmental Dyslexia
Publisher: Frontiers Media SA
Date: 08-07-2020
An approach to base placement for effective collaboration of multiple autonomous industrial robots
Publisher: IEEE
Date: 05-2015
The effect of aging on the eccentricity dependency of orientation anisotropy of perceptual surround suppression
Publisher: Association for Research in Vision and Ophthalmology (ARVO)
Date: 27-01-2021
DOI: 10.1167/JOV.21.1.13
Comparison of two different objective functions in 2D point feature SLAM
Publisher: Elsevier BV
Date: 11-2018
Maximizing the Weighted Number of Spanning Trees: Near-$t$-Optimal Graphs
Publisher: arXiv
Date: 2016
Information processing bottlenecks in macaque posterior parietal cortex: An attentional blink?
Publisher: Springer Science and Business Media LLC
Date: 29-05-2013
DOI: 10.1007/S00221-013-3569-2
Abstract: When two brief stimuli are presented in rapid succession, our ability to attend and recognize the second stimulus is impaired if our attentional resources are devoted to processing the first. Such inability (termed the "attentional blink" in human studies) arises around 200-500 ms following the onset of the first stimulus. We trained two monkeys on a delayed-match-to-s le task where both the location and orientation of two successively presented grating patches had to be matched. When the delay between the two gratings was varied, monkey's behavioral performance (d') was affected in a way that was analogous to the attentional blink in humans. Furthermore, a subset of neurons in the monkey's lateral intraparietal area, known to be crucial in the control of attention, closely followed the variation in d', even on occasions when d' followed an atypical pattern. Our results provide the first behavioral demonstration of an attentional bottleneck in the macaque of a type similar to the human attentional blink as well as a possible single-neuron correlate of the phenomenon.
Irregularity in neocortical spike trains: Influence of measurement factors and another method of estimation
Publisher: Elsevier BV
Date: 10-2006
DOI: 10.1016/J.JNEUMETH.2006.05.006
Abstract: Irregularity in the interspike interval is a common phenomenon especially in the neocortex. A measure of this random variation in the spacing between neuronal spikes is usually obtained with the coefficient of variation CV (standard deviation/mean interspike interval). In excitable cells, the standard deviation in the interspike interval can be large and the mean firing rate often fluctuates. As a result, there can be substantial variability in the value of the CV computed for the same spike train using only slightly different s les as we show. Moreover, these CV values can be comparatively meaningless unless certain conditions are met. In doing so some researchers have selectively s led data over a stable mean while others have used a wide range of trial times or subsets thereof (capture window) to compute the CV. This has made interpretation of the raw CV cumbersome. We demonstrate that the CV has a triple sensitivity, namely, for the size of the capture window, the spike count and the refractory period. We assuage these difficulties by introducing a modified term, the coefficient of variation proportion of maximum (CVpm) that offers transportability across different experimental conditions by compensating for the triplet.
Visual search efficiency and functional visual cortical size in children with and without dyslexia
Publisher: Elsevier BV
Date: 05-2021
Apparent movement with subjective contours
Publisher: Elsevier BV
Date: 07-1973
DOI: 10.1016/0042-6989(73)90219-8
Abstract: DREF [DRE (DNA replication-related element)-binding factor] controls the transcription of numerous genes in Drosophila, many involved in nuclear DNA (nDNA) replication and cell proliferation, three in mitochondrial DNA (mtDNA) replication and two in mtDNA transcription termination. In this work, we have analysed the involvement of DREF in the expression of the known remaining genes engaged in the minimal mtDNA replication (d-mtDNA helicase) and transcription (the activator d-mtTFB2) machineries and of a gene involved in mitochondrial mRNA translation (d-mtTFB1). We have identified their transcriptional initiation sites and DRE sequences in their promoter regions. Gel-shift and chromatin immunoprecipitation assays demonstrate that DREF interacts in vitro and in vivo with the d-mtDNA helicase and d-mtTFB2, but not with the d-mtTFB1 promoters. Transient transfection assays in Drosophila S2 cells with mutated DRE motifs and truncated promoter regions show that DREF controls the transcription of d-mtDNA helicase and d-mtTFB2, but not that of d-mtTFB1. RNA interference of DREF in S2 cells reinforces these results showing a decrease in the mRNA levels of d-mtDNA helicase and d-mtTFB2 and no changes in those of the d-mtTFB1. These results link the genetic regulation of nuclear DNA replication with the genetic control of mtDNA replication and transcriptional activation in Drosophila.
Attentional asymmetry between visual hemifields is related to habitual direction of reading and its implications for debate on cause and effects of dyslexia
Publisher: Wiley
Date: 07-12-2018
DOI: 10.1002/DYS.1574
Abstract: A major controversy regarding dyslexia is whether any of the many visual and phonological deficits found to be correlated with reading difficulty cause the impairment or result from the reduced amount of reading done by dyslexics. We studied this question by comparing a visual capacity in the left and right visual hemifields in people habitually reading scripts written right-to-left or left-to-right. Selective visual attention is necessary for efficient visual search and also for the sequential recognition of letters in words. Because such attentional allocation during reading depends on the direction in which one is reading, asymmetries in search efficiency may reflect biases arising from the habitual direction of reading. We studied this by examining search performance in three cohorts: (a) left-to-right readers who read English fluently (b) right-to-left readers fluent in reading Farsi but not any left-to-right script and (c) bilingual readers fluent in English and in Farsi, Arabic, or Hebrew. Left-to-right readers showed better search performance in the right hemifield and right-to-left readers in the left hemifield, but bilingual readers showed no such asymmetries. Thus, reading experience biases search performance in the direction of reading, which has implications for the cause and effect relationships between reading and cognitive functions.
Subcortical mechanisms in orientation sensitivity of cat visual cortical cells
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 02-1992
DOI: 10.1097/00001756-199202000-00016
Abstract: The orientation biases seen in the responses of neurones of the dorsal lateral geniculate nucleus (dLGN) can be reduced by the local application of the GABA antagonist, bicuculline methiodide. This fact was exploited to investigate whether these biases are important for cortical orientation selectivity by measuring the orientation sensitivity of cortical cells before and during iontophoretic administration of bicuculline in the topographically corresponding region of the dLGN. This procedure led to a significant reduction in the orientation sensitivity of the cortical cell. The results suggest that subcortical orientation biases are at least partly responsible for the orientation sensitivity seen at the level of the striate cortex.
Multi-Session SLAM Over Low Dynamic Workspace Using RGBD Sensor
Publisher: WORLD SCIENTIFIC
Date: 25-08-2016
Excitation and inhibition in orientation selectivity of cat visual cortex neurons revealed by whole-cell recordings in vivo
Publisher: Cambridge University Press (CUP)
Date: 11-1993
DOI: 10.1017/S0952523800010257
Abstract: One striking transformation in response properties that occurs in the geniculo-cortical pathway is the appearance of a high degree of orientation selectivity in the cortex. This property may be conceived as arising purely from the excitatory inputs to the cell, as being structured largely by the inhibition a cortical cell receives or could be due to a combination of the two. We have studied the contributions of excitatory and inhibitory inputs to cortical cells' orientation selectivity by analyzing the postsynaptic potentials evoked in cat striate neurones by flashing stimuli of different orientations. We made these recordings using the in vivo whole-cell technique (Xing Pei et al., 1991), which provides more stable and reliable results than classical intracellular recording methods. Our results show that the cat striate cortex exhibits a variety of mechanisms to achieve orientation selectivity. Orientation selectivity of a particular cell can be created by excitatory, by inhibitory, or by a combination of both mechanisms.
Line matching based on planar homography for stereo aerial images
Publisher: Elsevier BV
Date: 06-2015
Dynamics of coherent activity between cortical areas defines a two-stage process of selective attention
Publisher: Cold Spring Harbor Laboratory
Date: 11-02-2020
DOI: 10.1101/2020.02.09.940791
Abstract: Analysing a visual scene requires the brain to briefly keep in memory potentially relevant parts and then direct attention to their locations for detailed processing. To reveal the neuronal basis of the underlying working memory and top-down attention processes, we trained macaques to match two patterns presented with a delay between them. As the above processes are likely to require communication between brain regions, and the parietal cortex is involved in spatial attention, we simultaneously recorded neuronal activities from the interconnected parietal and middle temporal areas. We found that mnemonic information about the first pattern was retained in coherent oscillating activity between the areas in high-frequency bands, followed by coherent activity in low-frequency bands that mediate top-down attention on the relevant location. Gamma coherence allows retaining object features in a saliency map while lower frequency coherence facilitates attention.
Online estimation of ocean current from sparse GPS data for underwater vehicles
Publisher: IEEE
Date: 05-2019
IN2LAMA: INertial Lidar Localisation And Mapping
Publisher: IEEE
Date: 05-2019
Diversity of feature selectivity in macaque visual cortex arising from limited number of broadly-tuned input channels
Publisher: Cold Spring Harbor Laboratory
Date: 23-04-2018
DOI: 10.1101/291229
Abstract: Spikes (action potential) responses of most primary visual cortical cells in the macaque are sharply tuned for the orientation of a line or an edge and neurons preferring similar orientations are clustered together in cortical columns. The preferred stimulus orientation of these columns span the full range of orientations, as observed in recordings of spikes, which represent the outputs of cortical neurons. However, when we imaged also the thalamic input to these cells that occur on a larger spatial scale, we found that the orientation domain map of the primary visual cortex did not show the ersity of orientations exhibited by signals representing outputs of the cells. This map was dominated by just the one orientation that is most commonly represented in subcortical responses. This supports cortical feature selectivity and columnar architecture being built upon feed-forward signals transmitted from the thalamus in a very limited number of broadly-tuned input channels.
Predicting Objective Function Change in Pose-Graph Optimization
Publisher: IEEE
Date: 10-2019
Synaptic transmission in the neocortex during reversible cooling
Publisher: Elsevier BV
Date: 06-2000
DOI: 10.1016/S0306-4522(00)00109-3
Abstract: We studied the effects of reversible cooling on synaptic transmission in slices of rat visual cortex. Cooling had marked monotonic effects on the temporal properties of synaptic transmission. It increased the latency of excitatory postsynaptic potentials and prolonged their time-course. Effects were non-monotonic on other properties, such as litude of excitatory postsynaptic potentials and generation of spikes. The litude of excitatory postsynaptic potentials increased, decreased, or remain unchanged while cooling down to about 20 degrees C, but thereafter it declined gradually in all cells studied. The effect of moderate cooling on spike generation was increased excitability, most probably due to the ease with which a depolarized membrane potential could be brought to spike threshold by a sufficiently strong excitatory postsynaptic potential. Stimuli that were subthreshold above 30 degrees C could readily generate spikes at room temperature. Only at well below 10 degrees C could action potentials be completely suppressed. Paired-pulse facilitation was less at lower temperatures, indicating that synaptic dynamics are different at room temperature as compared with physiological temperatures. These results have important implications for extrapolating in vitro data obtained at room temperatures to higher temperatures. The data also emphasize that inactivation by cooling might be a useful tool for studying interactions between brain regions, but the data recorded within the cooled area do not allow reliable conclusions to be drawn about neural operations at normal temperatures.
A framework for multi-session RGBD SLAM in low dynamic workspace environment
Publisher: Elsevier BV
Date: 2016
The role of contours in stereopsis
Publisher: Springer Science and Business Media LLC
Date: 04-1973
DOI: 10.1038/242412A0
Abstract: To investigate the co-effect of Demand-control-support (DCS) model and Effort-reward Imbalance (ERI) model on the risk estimation of depression in humans in comparison with the effects when they are used respectively. A total of 3 632 males and 1 706 females from 13 factories and companies in Henan province were recruited in this cross-sectional study. Perceived job stress was evaluated with the Job Content Questionnaire and Effort-Reward Imbalance Questionnaire (Chinese version). Depressive symptoms were assessed by using the Center for Epidemiological Studies Depression Scale (CES-D). DC (demands/job control ratio) and ERI were shown to be independently associated with depressive symptoms. The outcome of low social support and overcommitment were similar. High DC and low social support (SS), high ERI and high overcommitment, and high DC and high ERI posed greater risks of depressive symptoms than each of them did alone. ERI model and SS model seem to be effective in estimating the risk of depressive symptoms if they are used respectively. The DC had better performance when it was used in combination with low SS. The effect on physical demands was better than on psychological demands. The combination of DCS and ERI models could improve the risk estimate of depressive symptoms in humans.
Neural Mechanisms of Visual Attention: How Top-Down Feedback Highlights Relevant Locations
Publisher: American Association for the Advancement of Science (AAAS)
Date: 15-06-2007
Abstract: Attention helps us process potentially important objects by selectively increasing the activity of sensory neurons that represent the relevant locations and features of our environment. This selection process requires top-down feedback about what is important in our environment. We investigated how parietal cortical output influences neural activity in early sensory areas. Neural recordings were made simultaneously from the posterior parietal cortex and an earlier area in the visual pathway, the medial temporal area, of macaques performing a visual matching task. When the monkey selectively attended to a location, the timing of activities in the two regions became synchronized, with the parietal cortex leading the medial temporal area. Parietal neurons may thus selectively increase activity in earlier sensory areas to enable focused spatial attention.
MIS-SLAM: Real-time Large Scale Dense Deformable SLAM System in Minimal Invasive Surgery Based on Heterogeneous Computing
Publisher: arXiv
Date: 2018
A neural framework for spontaneous development of orientation selectivity in the primary visual cortex
Publisher: Cold Spring Harbor Laboratory
Date: 08-09-2022
DOI: 10.1101/2022.09.06.505990
Abstract: The mechanism or microcircuitry behind orientation selectivity in primary visual cortex (V1), and the means by which it develops without supervision or visual input, both remain unresolved questions. Work on the developmental question has assumed the prevalent spatial convergence model of orientation selectivity as the target mechanism. Encouraged by growing evidence challenging both the completeness of this model and its developmental viability, we investigated an alternative scheme. Accordingly, we demonstrate computationally how a scheme in which orientation selectivity originates from the orientation biases already in the retina and lateral geniculate nucelus (LGN) can answer both the mechanistic and developmental questions. In this scheme, the ergence of outputs from the retina allows retinal spontaneous activity to create correlations within the LGN. These correlations in turn allow a Hebbian plasticity mechanism to strengthen those LGN inputs to V1 which carry similar orientation biases and thus provide an orientation tuned excitatory input.
The role of colour perception and pattern recognition in stereopsis
Publisher: Elsevier BV
Date: 02-1973
DOI: 10.1016/0042-6989(73)90133-8
Abstract: The nuclear receptor subfamily 4 (NR4A) is composed of 3 related proteins sharing a DNA binding domain (DBD) and a ligand-binding domain (LBD). The nuclear receptor related 1 protein (Nurr1 or NR4A2) plays a key role in the maintenance of the dopaminergic system. Dopamine dysfunctions associated with the Nurr1 gene include Parkinson's disease, schizophrenia and manic depression among others. Furthermore, recent evidence indicates that Nurr1 is also expressed in other brain areas such as the hippoc us and plays critical roles for learning and memory. The other members of the family are nerve growth factor IB (Nur77 or NR4A1) and neuron-derived orphan receptor 1 (NOR1 or NR4A3). To help investigate the precise functional roles of Nurr1 in dopaminergic and other brain region-related neuronal dysfunctions antibodies devoid of cross-reactivities against Nur77 and NOR1 were needed. Since the proteins are more ergent in their LBDs than in their DNA binding domains immunization with purified LBDs should yield antibodies specific for Nurr1 with minimal reactivities against Nur77 and/or NOR1. Although anti-Nurr1 antibodies were successfully generated these showed significant immunoreactivity against the other members of the family. Affinity chromatography over immobilized Protein A followed by pre-adsorption against immobilized Nur77 and NOR1 LBDs yielded Nurr1 specific antibodies free of cross-reactivity. Here, we selectively target antibodies against a specific member of a highly conserved family of proteins by immunizing animals with their most ergent regions followed by removing cross reactive antibodies by pre-adsorption. The goal of the protocol is to increase polyclonal antibodies specificity through pre-adsorption against cross-reactive antigens.
Topological local-metric framework for mobile robots navigation: a long term perspective
Publisher: Springer Science and Business Media LLC
Date: 29-03-2019
Space and spatial frequency: analysis and representation in the macaque striate cortex
Publisher: Springer Science and Business Media LLC
Date: 09-1986
DOI: 10.1007/BF00238196
Abstract: Ventricular noncompaction has been recognized as a distinct form of rare cardiomyopathy characterized by numerous, prominent ventricular trabeculations and deep intertrabecular recesses and is caused by a disorder of endomyocardial morphogenesis. Concomitance of either valvular pathologies or complete atrioventricular block with biventricular noncompaction has rarely been reported. Herein, we present a case of 67 years old male presented with syncopal attack and congestive heart failure due to biventricular noncompaction with significant left ventricular dysfunction associated with complete atrioventricular block. He was formerly diagnosed as dilated cardiomyopathy for last 2 years. Review of literatures of all reported cases has been discussed.
Robust Incremental SLAM Under Constrained Optimization Formulation
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 04-2018
Coding of spatial attention priorities and object features in the macaque lateral intraparietal cortex.
Publisher: Wiley
Date: 03-2017
DOI: 10.14814/PHY2.13136
Neural underpinnings of dyslexia as a disorder of visuo-spatial attention
Publisher: Informa UK Limited
Date: 2004
DOI: 10.1111/J.1444-0938.2004.TB03138.X
Abstract: For nearly 100 years, the underlying cause of dyslexia has been a matter of much debate, with widely varying viewpoints that have ranged from considering dyslexia as largely a learning disability to claims that it is essentially a perceptual defect occurring early along the visual pathway. This paper reviews some of this literature with particular reference to the studies that have implicated a defect in the afferent visual pathways in the aetiology of the disorder, then goes on to outline a neural theory of how functionally distinct parallel pathways in vision interact with each other in the process of reading and suggests how a defect in these pathways can lead to reading difficulties. Central to the proposed scheme is the suggestion that a fast-track pathway, arising from the magnocellular cells in the retina and acting through an attentional mechanism, has a gating function in spotlighting the in idual letters of a text in a sequential fashion. That such gating occurs at the level of the primary visual cortex is supported by recent physiological evidence concerning attentional mechanisms.
Incremental SQP method for constrained optimization formulation in SLAM
Publisher: IEEE
Date: 11-2016
Sharpness constancy during movement perception (short note)
Publisher: SAGE Publications
Date: 03-1974
DOI: 10.1068/P030097
Abstract: Cashew apple bagasse is a byproduct of cashew peduncle juice processing. Such waste is a source of carotenoids, but it is usually discarded after the juice extraction. The objective of this work was to study the influence of pectinolytic and cellulolytic enzyme complexes on cashew bagasse maceration in order to obtain carotenoids. It was observed that maceration with the enzymatic complex Pectinex Batch AR showed a higher content of carotenoids, with an overall gain of 79 % over the control carried out without enzyme complex addition.
An Integrated Neuronal Model of Claustral Function in Timing the Synchrony Between Cortical Areas
Publisher: Frontiers Media SA
Date: 05-02-2019
Device-free localization via an extreme learning machine with parameterized geometrical feature extraction
Publisher: MDPI AG
Date: 17-04-2017
DOI: 10.3390/S17040879
Segregation of short-wavelength-sensitive (S) cone signals in the macaque dorsal lateral geniculate nucleus.
Publisher: Wiley
Date: 10-2009
A critique of current developments in simultaneous localization and mapping
Publisher: SAGE Publications
Date: 09-2016
Abstract: The number of research publications dealing with the simultaneous localization and mapping problem has grown significantly over the past 15 years. Many fundamental and practical aspects of simultaneous localization and mapping have been addressed, and some efficient algorithms and practical solutions have been demonstrated. The aim of this paper is to provide a critical review of current theoretical understanding of the fundamental properties of the SLAM problem, such as observability, convergence, achievable accuracy and consistency. Recent research outcomes associated with these topics are briefly discussed together with potential future research directions.
ParallaxBA: Bundle adjustment using parallax angle feature parametrization
Publisher: SAGE Publications
Date: 26-01-2015
Abstract: The main contribution of this paper is a novel feature parametrization based on parallax angles for bundle adjustment (BA) in structure and motion estimation from monocular images. It is demonstrated that under certain conditions, describing feature locations using their Euclidean XYZ coordinates or using inverse depth in BA leads to ill-conditioned normal equations as well as objective functions that have very small gradients with respect to some of the parameters describing feature locations. The proposed parallax angle feature parametrization in BA (ParallaxBA) avoids both of the above problems leading to better convergence properties and more accurate motion and structure estimates. Simulation and experimental datasets are used to demonstrate the impact of different feature parametrizations on BA, and the improved convergence, efficiency and accuracy of the proposed ParallaxBA algorithm when compared with some existing BA packages such as SBA, sSBA and g2o. The C/C++ source code of ParallaxBA is available on OpenSLAM ( openslam.org/ ).
Comparison of EKF based SLAM and Optimization based SLAM Algorithms
Publisher: IEEE
Date: 05-2018
A sparse separable SLAM back-end
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 12-2016
Dynamic Reconstruction of Deformable Soft-Tissue With Stereo Scope in Minimal Invasive Surgery
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2018
MIS-SLAM: Real-Time Large-Scale Dense Deformable SLAM System in Minimal Invasive Surgery Based on Heterogeneous Computing
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 10-2018
Fast, on-board, model-aided visual-inertial odometry system for quadrotor micro aerial vehicles
Publisher: IEEE
Date: 05-2016
Dynamics of the orientation tuning of postsynaptic potentials in the cat visual cortex
Publisher: Cambridge University Press (CUP)
Date: 07-1995
DOI: 10.1017/S0952523800008919
Abstract: We evaluated the dynamic aspects of the orientation tuning of the input to cat visual cortical neurons by analyzing the postsynaptic potentials (PSPs) evoked by flashing bars of light. The PSPs were recorded using in vivo whole-cell technique, and we analyzed the orientation tuning during subsequent temporal windows after stimulus onset and offset. Our results show that the litudes of the postsynaptic potential are reliably tuned to orientation and matching that of the spike responses only during certain temporal windows. During the first 100 ms after stimulus presentation, orientation tuning of the membrane potential underwent regular changes. Within particular intervals, orientation tuning of the input was much sharper than that estimated according to the whole response. In most cells, optimal orientation was usually stable over the whole period. In several cells which had a second hump of EPSPs in the response, this second hump was tuned to the same orientation as the first one, but always showed sharper tuning. Estimation of the integration time revealed sufficient delay between the appearance of EPSPs and spikes, to let inhibition influence spike generation. These results show that orientation selectivity of the input to cortical cells is a dynamic function, and also indicate the possibility of temporal coding in the visual system.
3D Lidar-IMU Calibration based on Upsampled Preintegrated Measurements for Motion Distortion Correction
Publisher: IEEE
Date: 05-2018
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Location: United Kingdom of Great Britain and Northern Ireland
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