ORCID Profile
0000-0001-9632-0735
Current Organisation
Australian National University
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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)
Animal Physiology - Systems | Neurosciences | Sensory Processes, Perception And Performance | Physiology | Biological Psychology (Neuropsychology, Psychopharmacology, Physiological Psychology) | Decision Making | Sensory Systems | Central Nervous System | Peripheral Nervous System | Psychology | Central Nervous System | Sensory Processes, Perception and Performance | Neurocognitive Patterns and Neural Networks | Biomedical Instrumentation | Biological Physics | Systems Physiology |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in Psychology and Cognitive Sciences | Expanding Knowledge in the Biological Sciences | Behavioural and cognitive sciences | Nervous system and disorders | Biological sciences | Expanding Knowledge in the Medical and Health Sciences | Expanding Knowledge in Technology | Hearing, vision, speech and their disorders | Expanding Knowledge in Engineering | Expanding Knowledge in the Information and Computing Sciences
Related Links
Publications
Factors Affecting Frequency Discrimination of Vibrotactile Stimuli: Implications for Cortical Encoding
Publisher: Public Library of Science (PLoS)
Date: 20-12-2006
Vibrissal Texture Decoding
Publisher: Atlantis Press
Date: 22-11-2015
Detection of unusual Cryptosporidium parvum subtype in patients with gastrointestinal cancer in Egypt
Publisher: Springer Science and Business Media LLC
Date: 21-12-2022
Progressive fibrosing hypersensitivity pneumonitis: Why wait?
Publisher: Wiley
Date: 10-02-2022
DOI: 10.1111/RESP.14225
Abstract: See related article
Er81 Transcription Factor Fine-Tunes Striatal Cholinergic Interneuron Activity and Drives Habit Formation.
Publisher: Society for Neuroscience
Date: 13-04-2021
DOI: 10.1523/JNEUROSCI.0967-20.2021
Abstract: The molecular mechanisms tuning cholinergic interneuron (CIN) activity, although crucial for striatal function and behavior, remain largely unexplored. Previous studies report that the Etv1/Er81 transcription factor is vital for regulating neuronal maturation and activity. While Er81 is known to be expressed in the striatum during development, its specific role in defining CIN properties and the resulting consequences on striatal function is unknown. We report here that Er81 is expressed in CINs and its specific ablation leads to prominent changes in their molecular, morphologic, and electrophysiological features. In particular, the lack of Er81 lifies intrinsic delayed-rectifier and hyperpolarization-activated currents, which subsequently alters the tonic and phasic activity of CINs. We further reveal that Er81 expression is required for normal CIN pause and time-locked responses to sensorimotor inputs in awake mice. Overall, this study uncovers a new cell type-specific control of CIN function in the striatum which drives habit formation in adult male mice. SIGNIFICANCE STATEMENT Although previous studies have shown that cholinergic interneurons drive striatal activity and habit formation, the underlying molecular mechanisms controlling their function are unknown. Here we reveal that key cholinergic interneuron physiological properties are controlled by Er81, a transcription factor regulating neuronal activity and development in a cell-specific manner. Moreover, our findings uncover a link between the Er81-dependent molecular control of cholinergic interneuron function and habit formation in mice. These insights will contribute to the future enhancement of our understanding of disorders that involve behavioral inflexibility, such as autism and addiction.
Getting technical about awareness
Publisher: Elsevier BV
Date: 02-2008
DOI: 10.1016/J.TICS.2007.11.009
Abstract: It has recently been argued that post-decision wagering provides an objective measure of awareness. We critically evaluate this claim, emphasizing the distinction between performance without awareness and a reluctance to gamble in full awareness of weak sensory evidence. We address two key methodological issues. The first is the design of the pay-off matrix to reward a strategy of wagering that reflects the strength of sensory evidence. The second is the use of signal detection theory to analyze the resulting data. We argue that proper treatment of these issues is essential if post-decision wagering is to prove valuable in validating claims of perception without awareness in normal subjects and neuropsychological patients.
Deciphering the Spike Train of a Sensory Neuron: Counts and Temporal Patterns in the Rat Whisker Pathway
Publisher: Society for Neuroscience
Date: 06-09-2006
DOI: 10.1523/JNEUROSCI.1491-06.2006
Abstract: Rats achieve remarkable texture discriminations by sweeping their facial whiskers along surfaces. This work explores how neurons at two levels of the sensory pathway, trigeminal ganglion and barrel cortex, carry information about such stimuli. We identified two biologically plausible coding mechanisms, spike counts and patterns, and used “mutual information” to quantify how reliably neurons in anesthetized rats reported texture when “decoded” according to these candidate mechanisms. For discriminations between surfaces of different coarseness, spike counts could be decoded reliably and rapidly (within 30 ms after stimulus onset in cortex). Information increased as responses were considered as spike patterns with progressively finer temporal precision. At highest temporal resolution (spike sequences across six bins of 4 ms), the quantity of “information” in patterns rose 150% for ganglion neurons and 110% for cortical neurons above that in spike counts. In some cases, patterns permitted discriminations not supported by spike counts alone.
State-dependent changes in perception and coding in the mouse somatosensory cortex
Publisher: Cold Spring Harbor Laboratory
Date: 25-08-2020
DOI: 10.1101/2020.08.24.264127
Abstract: An animal’s behavioral state is reflected in the dynamics of cortical population activity and its capacity to process sensory information. To better understand the relationship between behavioral states and information processing, mice are trained to detect varying litudes of whisker-deflection under two-photon calcium imaging. Layer 2/3 neurons (n=1436) in the vibrissal primary somatosensory cortex are imaged across different behavioral states, defined based on detection performance (low to high-state) and pupil diameter. The neurometric curve in each behavioral state mirrors the corresponding psychometric performance, with calcium signals predictive of the animal’s choice outcome. High behavioral states are associated with lower network synchrony, extending over shorter cortical distances. The decrease of correlations in variability across neurons in the high state results in enhanced information transmission capacity at the population level. The observed state-dependent changes suggest that the coding regime within the first stage of cortical processing may underlie adaptive routing of relevant information through the sensorimotor system. Network synchrony and pupil diameter are coupled to changes in behavioral state. High behavioral state results in enhanced information transmission capacity at the population level, with neurometric curve in each behavioral state mirroring the corresponding psychometric performance Behavioral state and calcium signal in primary somatosensory cortex predict choice outcome. Lee et al. investigates the relationship between behavioral states and information processing in the primary somatosensory cortex. They demonstrate increases in behavioral state results in decrease cortical variability, enhanced information transmission capacity and stimulus encoding at the population level.
A spectrogram image based intelligent technique for automatic detection of autism spectrum disorder from EEG
Publisher: Public Library of Science (PLoS)
Date: 25-06-2021
DOI: 10.1371/JOURNAL.PONE.0253094
Abstract: Autism spectrum disorder (ASD) is a developmental disability characterized by persistent impairments in social interaction, speech and nonverbal communication, and restricted or repetitive behaviors. Currently Electroencephalography (EEG) is the most popular tool to inspect the existence of neurological disorders like autism biomarkers due to its low setup cost, high temporal resolution and wide availability. Generally, EEG recordings produce vast amount of data with dynamic behavior, which are visually analyzed by professional clinician to detect autism. It is laborious, expensive, subjective, error prone and has reliability issue. Therefor this study intends to develop an efficient diagnostic framework based on time-frequency spectrogram images of EEG signals to automatically identify ASD. In the proposed system, primarily, the raw EEG signals are pre-processed using re-referencing, filtering and normalization. Then, Short-Time Fourier Transform is used to transform the pre-processed signals into two-dimensional spectrogram images. Afterward those images are evaluated by machine learning (ML) and deep learning (DL) models, separately. In the ML process, textural features are extracted, and significant features are selected using principal component analysis, and feed them to six different ML classifiers for classification. In the DL process, three different convolutional neural network models are tested. The proposed DL based model achieves higher accuracy (99.15%) compared to the ML based model (95.25%) on an ASD EEG dataset and also outperforms existing methods. The findings of this study suggest that the DL based structure could discover important biomarkers for efficient and automatic diagnosis of ASD from EEG and may assist to develop computer-aided diagnosis system.
Behavioral correlates of the decision process in a dynamic environment: post-choice latencies reflect relative value and choice evaluation
Publisher: Frontiers Media SA
Date: 29-09-2015
Whisker sensory system – From receptor to decision
Publisher: Elsevier BV
Date: 04-2013
DOI: 10.1016/J.PNEUROBIO.2012.05.013
Abstract: One of the great challenges of systems neuroscience is to understand how the neocortex transforms neuronal representations of the physical characteristics of sensory stimuli into the percepts which can guide the animal's decisions. Here we present progress made in understanding behavioral and neurophysiological aspects of a highly efficient sensory apparatus, the rat whisker system. Beginning with the 1970s discovery of "barrels" in the rat and mouse brain, one line of research has focused on unraveling the circuits that transmit information from the whiskers to the sensory cortex, together with the cellular mechanisms that underlie sensory responses. A second, more recent line of research has focused on tactile psychophysics, that is, quantification of the behavioral capacities supported by whisker sensation. The opportunity to join these two lines of investigation makes whisker-mediated sensation an exciting platform for the study of the neuronal bases of perception and decision-making. Even more appealing is the beginning-to-end prospective offered by this system: the inquiry can start at the level of the sensory receptor and conclude with the animal's choice. We argue that rats can switch between two modes of operation of the whisker sensory system: (1) generative mode and (2) receptive mode. In the generative mode, the rat moves its whiskers forward and backward to actively seek contact with objects and to palpate the object after initial contact. In the receptive mode, the rat immobilizes its whiskers to optimize the collection of signals from an object that is moving by its own power. We describe behavioral tasks that rats perform in these different modes. Next, we explore which neuronal codes in sensory cortex account for the rats' discrimination capacities. Finally, we present hypotheses for mechanisms through which "downstream" brain regions may read out the activity of sensory cortex in order to extract the significance of sensory stimuli and, ultimately, to select the appropriate action.
Response to: Ritt et al., “Embodied Information Processing: Vibrissa Mechanics and Texture Features Shape Micromotions in Actively Sensing Rats.” Neuron 57, 599–613
Publisher: Elsevier BV
Date: 12-2008
Diagnosis and management of connective tissue disease‐associated interstitial lung disease in Australia and New Zealand: A position statement from the Thoracic Society of Australia and New Zealand*
Publisher: Wiley
Date: 24-11-2020
DOI: 10.1111/RESP.13977
Neural Network Poisson Models for Behavioural and Neural Spike Train Data
Publisher: Cold Spring Harbor Laboratory
Date: 14-07-2020
DOI: 10.1101/2020.07.13.201673
Abstract: One of the most important and challenging application areas for complex machine learning methods is to predict, characterize and model rich, multi-dimensional, neural data. Recent advances in neural recording techniques have made it possible to monitor the activities of a large number of neurons across different brain regions as animals perform behavioural tasks. This poses the critical challenge of establishing links between neural activity at a microscopic scale, which might for instance represent sensory input, and at a macroscopic scale, which then generates behaviour. Predominant modeling methods apply rather disjoint techniques to these scales by contrast, we suggest an end-to-end model which exploits recent developments of flexible, but tractable, neural network point-process models to characterize dependencies between stimuli, actions, and neural data. We apply this model to a public dataset collected using Neuropixel probes in mice performing a visually-guided behavioural task as well as a synthetic dataset produced from a hierarchical network model with reciprocally connected sensory and integration circuits intended to characterize animal behaviour in a fixed-duration motion discrimination task. We show that our model outperforms previous approaches and contributes novel insights into the relationships between neural activities and behaviour.
Enhanced Response of Neurons in Rat Somatosensory Cortex to Stimuli Containing Temporal Noise
Publisher: Oxford University Press (OUP)
Date: 21-08-2007
Abstract: Sensory stimuli under natural conditions often consist of a temporally irregular sequence of events, contrasting with the periodic sequences commonly used as stimuli in the laboratory. These experiments compared the responses of neurons in rat barrel cortex with trains of whisker movements with different frequencies each train possessed either a periodic or an irregular, "noisy" temporal structure. Periodic stimulus trains were composed of a sequence of 21 whisker deflections separated by 20 equal interdeflection intervals (IDIs). Noisy trains were matched for mean IDI but included intervals shorter and longer than the mean IDI. Cortical responses were equivalent for periodic and noisy stimuli for frequencies up to 10 Hz. Above 10 Hz, temporal noise led to a larger response magnitude, and this effect was lified as deflection frequency increased. Noise also caused a sharpening of the temporal precision of response to the in idual deflections of the stimulus train. Cortical neurons thus appear to be "tuned" to respond in a different way to stimuli characterized by temporal unpredictability. As a consequence, perceptual judgments that depend on somatosensory cortical firing rate may be affected by the presence of temporal noise.
Loss of the Er81 Transcription Factor in Cholinergic Cells Alters Striatal Activity and Habit Formation
Publisher: Cold Spring Harbor Laboratory
Date: 15-01-2020
DOI: 10.1101/2020.01.14.905497
Abstract: The finely-tuned activity of cholinergic interneurons (CINs) in the striatum is key for motor control, learning, and habit formation. Yet, the molecular mechanisms that determine their unique functional properties remain poorly explored. Using a combination of genetic and biochemical assays, in vitro and in vivo physiological characterisation, we report that selective ablation of the Er81 transcription factor leads to prominent changes in CIN molecular, morphological and electrophysiological features. In particular, the lack of Er81 lifies intrinsic delayed-rectifier and hyperpolarization-activated currents, which subsequently alters the tonic and phasic activity of CINs. We further demonstrate that these alterations enhance their pause and time-locked responses to sensorimotor inputs in awake mice. Finally, this study reveals an Er81-dependent developmental mechanism in CINs essential for habit formation in adult mice. - The Er81 transcription factor is expressed in striatal cholinergic interneurons (CINs) - Conditional deletion of Er81 alters key molecular, morphological and electrophysiological properties of CINs in adult mice - Deletion of Er81 reduces the intrinsic excitability of CINs by upregulating delayed rectifier and hyperpolarization-activated currents - Deletion of Er81 alters in vivo striatal activity and habit formation
Enhanced Sensory Coding in Mouse Vibrissal and Visual Cortex through TRPA1.
Publisher: Elsevier BV
Date: 07-2020
Immunological analysis of allergenic cross-reactivity between peanut and tree nuts
Publisher: Wiley
Date: 09-2003
Munker–White-Like Illusions without T-Junctions
Publisher: SAGE Publications
Date: 06-2002
DOI: 10.1068/P3348
Abstract: Some interpretations of the Munker–White illusion were evaluated by designing new versions of this illusion devoid of T-junctions (Munker–White-like images). The magnitudes of both Munker–White and Munker–White-like illusions were then quantified by using a brightness-matching technique. The results showed the effect to persist in all proposed versions. Since the illusion still remains despite the absence of explicit T-junctions and any explanation considering transparency, mechanisms other than those proposed by these interpretations must be responsible.
Rhythmic air-puff into nasal cavity modulates activity across multiple brain areas: A non-invasive brain stimulation method to reduce ventilator-induced memory impairment
Publisher: Elsevier BV
Date: 05-2021
Benefits of a virtual interstitial lung disease multidisciplinary meeting in the face of COVID ‐19
Publisher: Wiley
Date: 19-04-2021
DOI: 10.1111/RESP.14062
Adaptation Improves Neural Coding Efficiency Despite Increasing Correlations in Variability
Publisher: Society for Neuroscience
Date: 30-01-2013
DOI: 10.1523/JNEUROSCI.3449-12.2013
Abstract: Exposure of cortical cells to sustained sensory stimuli results in changes in the neuronal response function. This phenomenon, known as adaptation, is a common feature across sensory modalities. Here, we quantified the functional effect of adaptation on the ensemble activity of cortical neurons in the rat whisker-barrel system. A multishank array of electrodes was used to allow simultaneous s ling of neuronal activity. We characterized the response of neurons to sinusoidal whisker vibrations of varying litude in three states of adaptation. The adaptors produced a systematic rightward shift in the neuronal response function. Consistently, mutual information revealed that peak discrimination performance was not aligned to the adaptor but to test litudes 3–9 μm higher. Stimulus presentation reduced single neuron trial-to-trial response variability (captured by Fano factor) and correlations in the population response variability (noise correlation). We found that these two types of variability were inversely proportional to the average firing rate regardless of the adaptation state. Adaptation transferred the neuronal operating regime to lower rates with higher Fano factor and noise correlations. Noise correlations were positive and in the direction of signal, and thus detrimental to coding efficiency. Interestingly, across all population sizes, the net effect of adaptation was to increase the total information despite increasing the noise correlation between neurons.
Operating characteristics and awareness
Publisher: John Benjamins Publishing Company
Date: 2010
Prediction error and repetition suppression have distinct effects on neural representations of visual information
Publisher: eLife Sciences Publications, Ltd
Date: 14-12-2018
DOI: 10.7554/ELIFE.33123
Abstract: Predictive coding theories argue that recent experience establishes expectations in the brain that generate prediction errors when violated. Prediction errors provide a possible explanation for repetition suppression, where evoked neural activity is attenuated across repeated presentations of the same stimulus. The predictive coding account argues repetition suppression arises because repeated stimuli are expected, whereas non-repeated stimuli are unexpected and thus elicit larger neural responses. Here, we employed electroencephalography in humans to test the predictive coding account of repetition suppression by presenting sequences of visual gratings with orientations that were expected either to repeat or change in separate blocks of trials. We applied multivariate forward modelling to determine how orientation selectivity was affected by repetition and prediction. Unexpected stimuli were associated with significantly enhanced orientation selectivity, whereas selectivity was unaffected for repeated stimuli. Our results suggest that repetition suppression and expectation have separable effects on neural representations of visual feature information.
Tunable Polymeric Mixed Micellar Nanoassemblies of Lutrol F127/Gelucire 44/14 for Oral Delivery of Praziquantel: A Promising Nanovector against Hymenolepis nana in Experimentally-Infected Rats
Publisher: MDPI AG
Date: 23-09-2022
DOI: 10.3390/PHARMACEUTICS14102023
Abstract: Hymenolepiasis represents a parasitic infection of common prevalence in pediatrics with intimidating impacts, particularly amongst immunocompromised patients. The present work aimed to snowball the curative outcomes of the current mainstay of hymenolepiasis chemotherapy, praziquantel (PRZ), through assembly of polymeric mixed micelles (PMMs). Such innovative nano-cargo could consolidate PRZ hydrosolubility, extend its circulation time and eventually upraise its bioavailability, thus accomplishing a nanoparadigm for hymenolepiasis tackling at lower dose levels. For consummating this goal, PRZ-PMMs were tailored via thin-film hydration technique integrating a binary system of Lutrol F127 and Gelucire 44/14. Box-Behnken design was planned for optimizing the nanoformulation variables employing Design-Expert® software. Also, in Hymenolepis nana-infected rats, the pharmacodynamics of the optimal micellar formulation versus the analogous crude PRZ suspension were scrutinized on the 1st and 3rd days after administration of a single oral dose (12.5 or 25 mg/kg). Moreover, in vitro ovicidal activity of the monitored formulations was estimated utilizing Fuchsin vital stain. Furthermore, the in vivo pharmacokinetics were assessed in rats. The optimum PRZ-PMMs disclosed conciliation between thermodynamic and kinetic stability, high entrapment efficiency (86.29%), spherical nanosized morphology (15.18 nm), and controlled-release characteristics over 24 h (78.22%). 1H NMR studies verified PRZ assimilation within the micellar core. Additionally, the in vivo results highlighted a significant boosted efficacy of PRZ-PMMs manifested by fecal eggs output and worm burden reduction, which was clearly evident at the lesser PRZ dose, besides a reversed effect for the intestinal histological disruptions. At 50 µg/mL, PRZ-PMMs increased the percent of non-viable eggs to 100% versus 47% for crude PRZ, whilst shell destruction and loss of embryo were only clear with the applied nano-cargo. Moreover, superior bioavailability by 3.43-fold with elongated residence time was measured for PRZ-PMMs compared to PRZ suspension. Practically, our results unravel the potential of PRZ-PMMs as an oral promising tolerable lower dose nanoplatform for more competent PRZ mass chemotherapy.
A Comparison of Neuronal and Behavioral Detection and Discrimination Performances in Rat Whisker System
Publisher: American Physiological Society
Date: 2011
Abstract: We used the rat whisker touch as a model system to investigate the correlation between the response function of cortical neurons and the behavior of rats in a sensory detection versus discrimination task. The rat whisker–barrel system is structurally well characterized and represents one of the main channels through which rodents collect information about the environment. In experiment 1, we recorded neuronal activity ( n = 235) in the whisker area of the rat somatosensory cortex in anesthetized rats while applying vibrotactile stimuli of varying litudes to the whiskers. Neurons showed a characteristic sigmoidal input–output function, with an accelerating nonlinearity at low stimulus litudes and a compressive nonlinearity at high stimulus litudes. We further quantified the performance of in idual neurons for stimulus detection and for discrimination across different stimulus pairs with identical litude differences. For near-threshold stimuli, the neuronal discrimination performance surpassed the detection performance despite the fact that detection and discrimination represented identical litude differences. This is consistent with the accelerating nonlinearity observed at low stimulus intensities. In the second stage of the experiment, four rats were trained to select the higher- litude stimulus between two vibrations applied to their whiskers. Similar to neuronal results, the rats' performance was better for the discrimination task compared with the detection task. The behavioral performance followed the same trend as that of the population of in idual neurons. Both behavioral and neuronal data are consistent with the “pedestal effect” previously reported in human psychophysics.
Transplantation of rat dental pulp stem cells facilities post-lesion recovery in the somatosensory whisker cortex of male Wistar rats
Publisher: Elsevier BV
Date: 08-2021
DOI: 10.1016/J.BRAINRESBULL.2021.04.028
Abstract: Damage to somatosensory "barrel" cortex reduces the rats' behavioral sensitivity in discrimination of tactile stimuli. Here, we examined how transplantation of stem cells into the lesioned barrel cortex can help in recovery of sensory capacities. We induced mechanical lesions in the right barrel cortex area of male rats. Three days after lesioning, rats received one of three transplantation types: un-differentiated dental pulp stem cells (U-DPSCs) or differentiated dental pulp stem cells (D-DPSCs), or cell medium (vehicle). A fourth group of rats were control without any Surgery. For 4 consecutive weeks, starting one week after transplantation, we evaluated the rats' preference to explore novel textures as a measure of sensory discrimination ability, also measured the expression of glial fibrillary acidic protein (GFAP), Olig 2, nestin, neuronal nuclei (NeuN), brain-derived neurotrophic factor (BDNF) and neuroligin1 by immunohistochemistry and western blotting. Unilateral mechanical lesion decreased the rats' preferential exploration of novel textures compared to the control group across the 4-week behavioral tests. Following stem cell therapy, the rats' performance significantly improved at week 2-4 compared to the vehicle group. Compared to the control group, there was a significant decrease in the expression of nestin, NeuN, Olig 2, BDNF, neuroligin1 and a significant increase in the expression of GFAP in the vehicle group. The expression of the neural markers was significantly higher in DPSCs compared with the vehicle group whereas GFAP level was lower in DPSCs compared to vehicle. We found that DPSCs therapy affected a range of neuronal markers in the barrel cortex post lesion, and improved the rats' recovery for sensory discrimination.
Hippocampus-prefrontal coupling regulates recognition memory for novelty discrimination
Publisher: Society for Neuroscience
Date: 12-10-2021
DOI: 10.1523/JNEUROSCI.1202-21.2021
Abstract: Recognition memory provides the ability to distinguish familiar from novel objects and places, and is important for recording and updating events to guide appropriate behavior. The hippoc us (HPC) and medial prefrontal cortex (mPFC) have both been implicated in recognition memory, but the nature of HPC–mPFC interactions, and its impact on local circuits in mediating this process is not known. Here we show that novelty discrimination is accompanied with higher theta activity (4–10 Hz) and increased c-Fos expression in both these regions. Moreover, theta oscillations were highly coupled between the HPC and mPFC during recognition memory retrieval for novelty discrimination, with the HPC leading the mPFC, but not during initial learning. Principal neurons and interneurons in the mPFC responded more strongly during recognition memory retrieval compared with learning. Optogenetic silencing of HPC input to the mPFC disrupted coupled theta activity between these two structures, as well as the animals' (male Sprague Dawley rats) ability to differentiate novel from familiar objects. These results reveal a key role of monosynaptic connections between the HPC and mPFC in novelty discrimination via theta coupling and identify neural populations that underlie this recognition memory-guided behavior. SIGNIFICANCE STATEMENT Many memory processes are highly dependent on the interregional communication between the HPC and mPFC via neural oscillations. However, how these two brain regions coordinate their oscillatory activity to engage local neural populations to mediate recognition memory for novelty discrimination is poorly understood. This study revealed that the HPC and mPFC theta oscillations and their temporal coupling is correlated with recognition memory-guided behavior. During novel object recognition, the HPC drives mPFC interneurons to effectively reduce the activity of principal neurons. This study provides the first evidence for the requirement of the HPC–mPFC pathway to mediate recognition memory for novelty discrimination and describes a mechanism for how this memory is regulated.
On the presence of high-order interactions among somatosensory neurons and their effect on information transmission
Publisher: IOP Publishing
Date: 12-2009
Information-theoretic methods for studying population codes
Publisher: Elsevier BV
Date: 08-2010
DOI: 10.1016/J.NEUNET.2010.05.008
Abstract: Population coding is the quantitative study of which algorithms or representations are used by the brain to combine together and evaluate the messages carried by different neurons. Here, we review an information-theoretic approach to population coding. We first discuss how to compute the information carried by simultaneously recorded neural populations, and in particular how to reduce the limited s ling bias which affects the calculation of information from a limited amount of experimental data. We then discuss how to quantify the contribution of in idual members of the population, or the interaction between them, to the overall information encoded by the considered group of neurons. We focus in particular on evaluating what is the contribution of interactions up to any given order to the total information. We illustrate this formalism with applications to simulated data with realistic neuronal statistics and to real simultaneous recordings of multiple spike trains.
Peer Connect Service for people with pulmonary fibrosis in Australia: Participants' experiences and process evaluation
Publisher: Wiley
Date: 23-03-2020
DOI: 10.1111/RESP.13807
The impact of high-order interactions on the rate of synchronous discharge and information transmission in somatosensory cortex
Publisher: The Royal Society
Date: 28-08-2009
Abstract: Understanding the operations of neural networks in the brain requires an understanding of whether interactions among neurons can be described by a pairwise interaction model, or whether a higher order interaction model is needed. In this article we consider the rate of synchronous discharge of a local population of neurons, a macroscopic index of the activation of the neural network that can be measured experimentally. We analyse a model based on physics’ maximum entropy principle that evaluates whether the probability of synchronous discharge can be described by interactions up to any given order. When compared with real neural population activity obtained from the rat somatosensory cortex, the model shows that interactions of at least order three or four are necessary to explain the data. We use Shannon information to compute the impact of high-order correlations on the amount of somatosensory information transmitted by the rate of synchronous discharge, and we find that correlations of higher order progressively decrease the information available through the neural population. These results are compatible with the hypothesis that high-order interactions play a role in shaping the dynamics of neural networks, and that they should be taken into account when computing the representational capacity of neural populations.
Sensory Prioritization in Rats: Behavioral Performance and Neuronal Correlates.
Publisher: Society for Neuroscience
Date: 16-03-2016
DOI: 10.1523/JNEUROSCI.3636-15.2016
Abstract: Operating with some finite quantity of processing resources, an animal would benefit from prioritizing the sensory modality expected to provide key information in a particular context. The present study investigated whether rats dedicate attentional resources to the sensory modality in which a near-threshold event is more likely to occur. We manipulated attention by controlling the likelihood with which a stimulus was presented from one of two modalities. In a whisker session, 80% of trials contained a brief vibration stimulus applied to whiskers and the remaining 20% of trials contained a brief change of luminance. These likelihoods were reversed in a visual session. When a stimulus was presented in the high-likelihood context, detection performance increased and was faster compared with the same stimulus presented in the low-likelihood context. Sensory prioritization was also reflected in neuronal activity in the vibrissal area of primary somatosensory cortex: single units responded differentially to the whisker vibration stimulus when presented with higher probability compared with lower probability. Neuronal activity in the vibrissal cortex displayed signatures of multiplicative gain control and enhanced response to vibration stimuli during the whisker session. In conclusion, rats allocate priority to the more likely stimulus modality and the primary sensory cortex may participate in the redistribution of resources. SIGNIFICANCE STATEMENT Detection of low- litude events is critical to survival for ex le, to warn prey of predators. To formulate a response, decision-making systems must extract minute neuronal signals from the sensory modality that provides key information. Here, we identify the behavioral and neuronal correlates of sensory prioritization in rats. Rats were trained to detect whisker vibrations or visual flickers. Stimuli were embedded in two contexts in which either visual or whisker modality was more likely to occur. When a stimulus was presented in the high-likelihood context, detection was faster and more reliable. Neuronal recording from the vibrissal cortex revealed enhanced representation of vibrations in the prioritized context. These results establish the rat as an alternative model organism to primates for studying attention.
Whisker-Mediated Texture Discrimination
Publisher: Public Library of Science (PLoS)
Date: 26-08-2008
Prediction Error and Repetition Suppression Have Distinct Effects on Neural Representations of Visual Information
Publisher: Cold Spring Harbor Laboratory
Date: 03-11-2017
DOI: 10.1101/213710
Abstract: Predictive coding theories argue that recent experience establishes expectations in the brain that generate prediction errors when violated. Prediction errors provide a possible explanation for repetition suppression , where evoked neural activity is attenuated across repeated presentations of the same stimulus. The predictive coding account argues repetition suppression arises because repeated stimuli are expected, whereas non-repeated stimuli are unexpected and thus elicit larger neural responses. Here we employed electroencephalography in humans to test the predictive coding account of repetition suppression by presenting sequences of visual gratings with orientations that were expected either to repeat or change in separate blocks of trials. We applied multivariate forward modelling to determine how orientation selectivity was affected by repetition and prediction. Unexpected stimuli were associated with significantly enhanced orientation selectivity, whereas selectivity was unaffected for repeated stimuli. Our results suggest that repetition suppression and expectation have separable effects on neural representations of visual feature information.
Antifibrotic therapies for idiopathic pulmonary fibrosis
Publisher: Wiley
Date: 14-10-2021
Author response: Prediction error and repetition suppression have distinct effects on neural representations of visual information
Publisher: eLife Sciences Publications, Ltd
Date: 24-05-2018
Neuronal Activity in Rat Barrel Cortex Underlying Texture Discrimination
Publisher: Public Library of Science (PLoS)
Date: 13-11-2007
Functional analysis of cross-reactive immunoglobulin E antibodies: Peanut-specific immunoglobulin E sensitizes basophils to tree nut allergens
Publisher: Wiley
Date: 08-2005
Population Decoding in Rat Barrel Cortex: Optimizing the Linear Readout of Correlated Population Responses
Publisher: Public Library of Science (PLoS)
Date: 02-01-2014
Toxoplasma gondii and Neospora caninum Antibodies in Dogs and Cats from Egypt and Risk Factor Analysis
Publisher: MDPI AG
Date: 02-12-2022
DOI: 10.3390/PATHOGENS11121464
Abstract: Background: Toxoplasma gondii and Neospora caninum are major protozoan parasites of worldwide distribution and significance in veterinary medicine and, for T. gondii, in public health. Cats and dogs, as final hosts for T. gondii and N. caninum, respectively, have a key function in environmental contamination with oocysts and, thus, in parasite transmission. Very little is known about the prevalence of T. gondii infections in dogs and cats in Egypt, and even less about the prevalence of N. caninum in the same hosts. Methods: In the current study, 223 serum s les of both dogs (n = 172) and cats (n = 51) were investigated for specific antibodies to T. gondii and N. caninum using commercially available ELISAs. A risk factor analysis was conducted to identify factors associated with seropositivity. Results & discussion: Exposure to T. gondii was reported in 23.3% of the dogs and in 9.8% of the cats, respectively. In addition, N. caninum-specific antibodies were recorded in 5.8% of dogs and in 3.4% of cats. A mixed infection was found in two dogs (1.2%) and in one cat (2%). Antibodies to T. gondii in dogs were significantly more frequent in dogs aged 3 years or more and in male German Shepherds. As this breed is often used as watchdogs and was the most s led breed in Alexandria governorate, the purpose “watchdog” (compared to “stray” or “companion”), the male sex, and the governorate “Alexandria” also had a significantly higher seroprevalence for T. gondii. No factors associated with antibodies to N. caninum could be identified in dogs, and no significant factors were determined in cats for either T. gondii or N. caninum infection. Our study substantially adds to the knowledge of T. gondii infection in dogs and cats and presents data on N. caninum infection in cats for the first and in dogs in Egypt for the second time.
A protocol for simultaneous in vivo juxtacellular electrophysiology and local pharmacological manipulation in mouse cortex
Publisher: Elsevier BV
Date: 03-2021
TRPA1 expression and its functional activation in rodent cortex.
Publisher: The Royal Society
Date: 04-2017
DOI: 10.1098/RSOB.160314
Abstract: TRPA1 is a non-selective cation channel involved in pain sensation and neurogenic inflammation. Although TRPA1 is well established in a number of organs including the nervous system, its presence and function in the mammalian cortex remains unclear. Here, we demonstrate the expression of TRPA1 in rodent somatosensory cortex through immunostaining and investigate its functional activation by whole-cell electrophysiology, Ca 2+ imaging and two-photon photoswitching. Application of TRPA1 agonist (AITC) and antagonist (HC-030031) produced significant modulation of activity in layer 5 (L5) pyramidal neurons in both rats and mice AITC increased intracellular Ca 2+ concentrations and depolarized neurons, and both effects were blocked by HC-030031. These modulations were absent in the TRPA1 knockout mice. Next, we used optovin, a reversible photoactive molecule, to activate TRPA1 in in idual L5 neurons of rat cortex. Optical control of activity was established by applying a tightly focused femtosecond-pulsed laser to optovin-loaded neurons. Light application depolarized neurons ( n = 17) with the maximal effect observed at λ = 720 nm. Involvement of TRPA1 was further confirmed by repeating the experiment in the presence of HC-030031, which diminished the light modulation. These results demonstrate the presence of TRPA1 in L5 pyramidal neurons and introduce a highly specific approach to further understand its functional significance.
Superior colliculus modulates cortical coding of somatosensory information
Publisher: Springer Science and Business Media LLC
Date: 03-04-2020
DOI: 10.1038/S41467-020-15443-1
Abstract: The cortex modulates activity in superior colliculus via a direct projection. What is largely unknown is whether (and if so how) the superior colliculus modulates activity in the cortex. Here, we investigate this issue and show that optogenetic activation of superior colliculus changes the input–output relationship of neurons in somatosensory cortex, enhancing responses to low litude whisker deflections. While there is no direct pathway from superior colliculus to somatosensory cortex, we found that activation of superior colliculus drives spiking in the posterior medial (POm) nucleus of the thalamus via a powerful monosynaptic pathway. Furthermore, POm neurons receiving input from superior colliculus provide monosynaptic excitatory input to somatosensory cortex. Silencing POm abolished the capacity of superior colliculus to modulate cortical whisker responses. Our findings indicate that the superior colliculus, which plays a key role in attention, modulates sensory processing in somatosensory cortex via a powerful di-synaptic pathway through the thalamus.
Neuronal Encoding of Texture in the Whisker Sensory Pathway
Publisher: Public Library of Science (PLoS)
Date: 11-01-2005
Clinical allergy to hazelnut and peanut: Identification of T cell cross-reactive allergens
Publisher: S. Karger AG
Date: 2011
DOI: 10.1159/000321268
Abstract: i Background: /i Peanut and tree nut allergies are life-threatening conditions for many affected in iduals worldwide. Currently there is no cure. While co-allergy to peanut and tree nuts is a common clinical observation, and IgE cross-reactivity between peanut and tree nuts is reported, T cell cross-reactivity is poorly defined. i Methods: /i Hazelnut-specific T cell lines were established using peripheral blood mononuclear cells from 5 subjects with co-allergy to hazelnut and peanut. These lines were stimulated with hazelnut and peanut extracts and purified major peanut allergens, Ara h 1 and Ara h 2. Proliferation was determined by sup /sup H-thymidine incorporation and secretion of key Th1 (IFN-γ) and Th2 (IL-5) cytokines analysed by ELISA. i Results: /i Hazelnut-specific T cell lines from all 5 subjects proliferated upon stimulation with both hazelnut and peanut extracts and for 4 subjects, to Ara h 1 and/or Ara h 2. Proliferating cells were mainly CD4+ T cells and produced both IL-5 and IFN-γ in response to hazelnut and peanut stimulation. Mitogenicity of extracts and allergens was excluded by their lack of stimulation of house dust mite-specific T cells. i Conclusion: /i Our finding that hazelnut and peanut co-allergy is associated with cross-reactive T cell responses, driven partly by cross-reactivity to the major peanut allergens Ara h 1 and Ara h 2, points to future development of allergen immunotherapy by targeting cross-reactive T cells.
Forward modelling reveals dynamics of neural orientation tuning to unconscious visual stimuli during binocular rivalry
Publisher: Cold Spring Harbor Laboratory
Date: 12-03-2019
DOI: 10.1101/574905
Abstract: When different visual stimuli are presented to the two eyes, they typically compete for access to conscious perception, a phenomenon known as binocular rivalry . Previous studies of binocular rivalry have shown that neural responses to consciously suppressed stimuli are markedly diminished in magnitude, though they may still be encoded to some extent. Here we employed multivariate forward modelling of human electroencephalography (EEG) data to quantify orientation-selective responses to visual gratings during binocular rivalry. We found robust orientation tuning to both conscious and unconscious gratings. This tuning was enhanced for the suppressed stimulus well before it was available for conscious report. The same pattern was evident in the overall magnitude of neural responses, and it emerged even earlier than the changes in neural tuning. Taken together, our findings suggest that rivalry suppression affects broadband, non-orientation selective aspects of neural activity before refining fine-grained feature-selective information.
Stimulation of Locus Coeruleus Noradrenergic System Modulates Sensory Processing and Brain State in two Different Time Scales
Publisher: Cold Spring Harbor Laboratory
Date: 09-07-2020
DOI: 10.1101/2020.07.09.188615
Abstract: Locus Coeruleus (LC) noradrenergic system has widespread projections throughout the brain and affects sensory processing. LC modulation of sensory-evoked cortical activity and brain state is documented by electrical micro-stimulation, optogenetic experiments, and the local application of norepinephrine (NE). The temporal profile of the LC modulation of sensory response and brain state is not well characterized. Our goal in this study is to characterize this modulation. Here, we recorded neuronal activity from the barrel cortex (BC) of urethane-anesthetized rats while combining LC micro-stimulation with brief mechanical deflections of the whiskers at 10 different time lags (50-500 ms). We recorded spikes and local field potentials to quantify the neuronal activity and the brain state. LC micro-stimulation exhibited a biphasic effect on spontaneous activity of the BC: a period of suppression followed by a period of excitation. We observed a similar effect on the sensory-evoked response: at 50-ms lag, the evoked response decreased while at 150-ms lag, the early evoked response was facilitated. At 150 to 350-ms time lags, LC micro-stimulation caused a combined facilitation followed by suppression of the evoked response. In contrast to the fast transient effect of LC stimulation on BC spiking activity, brain state modulation started later and lasted longer. LC stimulation suppressed low-frequency activities that are associated with low arousal states. In summary, we found that LC modulation affects cortical processing of sensory inputs and the brain state at different time scales which are likely to involve distinct circuit mechanisms.
Noninformative Vision Causes Adaptive Changes in Tactile Sensitivity
Publisher: Society for Neuroscience
Date: 04-07-2007
DOI: 10.1523/JNEUROSCI.2102-07.2007
Abstract: The last few years have witnessed a rapid growth of research investigating how information is integrated across sensory modalities, a process at the core of our everyday perceptual experiences. The present study focuses on the integration of vision and touch and, in particular, how tactile perception is affected by a view of the relevant body part containing no information about the tactile stimulus itself. Previous studies have established that this “noninformative vision” can improve subsequent tactile discrimination (Kennett et al., 2001 Taylor-Clarke et al., 2004a), a finding we confirm in the present study. However, we also report here that noninformative vision impairs the detection of tactile stimuli and the discrimination of near-threshold stimuli. These effects are shown to resemble, and indeed combine additively with, shifts in discrimination and detection thresholds produced by adaptation to suprathreshold tactile stimulation. We conclude that noninformative vision of the body does not simply enhance somatosensory processing, but rather it induces adaptive changes in tactile sensitivity via shifts in gain control operating within a bimodal sensory system. This constitutes a novel means by which vision of the body can alter tactile perception.
Collicular Anatomy and Function
Publisher: Elsevier
Date: 2020
Economic losses, morpho-molecular identification, and identity of Fasciola species recovered from Egypt
Publisher: Springer Science and Business Media LLC
Date: 24-08-2022
Response dynamics of rat barrel cortex neurons to repeated sensory stimulation
Publisher: Springer Science and Business Media LLC
Date: 13-09-2017
DOI: 10.1038/S41598-017-11477-6
Abstract: Neuronal adaptation is a common feature observed at various stages of sensory processing. Here, we quantified the time course of adaptation in rat somatosensory cortex. Under urethane anesthesia, we juxta-cellularly recorded single neurons (n = 147) while applying a series of whisker deflections at various frequencies (2–32 Hz). For ~90% of neurons, the response per unit of time decreased with frequency. The degree of adaptation increased along the train of deflections and was strongest at the highest frequency. However, a subset of neurons showed facilitation producing higher responses to subsequent deflections. The response latency to consecutive deflections increased both for neurons that exhibited adaptation and for those that exhibited response facilitation. Histological reconstruction of neurons (n = 45) did not reveal a systematic relationship between adaptation profiles and cell types. In addition to the periodic stimuli, we applied a temporally irregular train of deflections with a mean frequency of 8 Hz. For 70% of neurons, the response to the irregular stimulus was greater than that of the 8 Hz regular. This increased response to irregular stimulation was positively correlated with the degree of adaptation. Altogether, our findings demonstrate high levels of ersity among cortical neurons, with a proportion of neurons showing facilitation at specific temporal intervals.
Sampling Time and Performance in Rat Whisker Sensory System
Publisher: Public Library of Science (PLoS)
Date: 31-12-2014
Temporal cueing enhances neuronal and behavioral discrimination performance in rat whisker system
Publisher: American Physiological Society
Date: 03-2019
Abstract: Since sensory systems operate with a finite quantity of processing resources, an animal would benefit from prioritizing processing of sensory stimuli within a time window that is expected to provide key information. This behavioral manifestation of such prioritization is known as attention. Here, we investigate attention with temporal cueing and its neuronal correlates in the rat primary vibrissal somatosensory (vS1) cortex. Rats were trained in a simple whisker vibration detection task. A vibration was presented at one of two spatial locations (left or right), sometimes after an unknown time interval and sometimes after receiving an auditory cue. The auditory cue provided temporal but not spatial information about the vibration. We found that for all rats ( n = 6), the auditory cue consistently enhanced detection of the vibration stimulus. Neuronal activity in vS1 cortex reflected the observed behavioral enhancement from temporal cueing with single units responded differentially to the whisker vibration stimulus when it was temporally predicted by the auditory cue, exhibiting an enhanced signal-to-noise ratio. Our findings indicate that rats are capable of prioritizing processing within a specified time window and provide evidence that the primary sensory cortex may participate in the temporal allocation of resources. NEW & NOTEWORTHY We demonstrate a novel paradigm of temporal cueing in rats. In a two-alternative whisker detection task, an auditory cue provided information about the timing of the stimulus but not the correct choice. In the presence of cue, detection was faster and more accurate, and neuronal activity from the primary somatosensory cortex revealed enhanced representation of vibrations. These results thus establish the rat as an alternative model organism to primates for studying temporal attention.
Correlation between Cortical State and Locus Coeruleus Activity: Implications for Sensory Coding in Rat Barrel Cortex
Publisher: Frontiers Media SA
Date: 24-03-2016
Human-like perceptual masking is difficult to observe in rats performing an orientation discrimination task
Publisher: Public Library of Science (PLoS)
Date: 21-11-2018
Activation of M1 cholinergic receptors in mouse somatosensory cortex enhances information processing and improves detection behaviour
Publisher: Cold Spring Harbor Laboratory
Date: 07-06-2023
DOI: 10.1101/2023.06.06.543981
Abstract: An important function of the brain is to form accurate representations of the world around us. To optimise sensory representations based on the demands of the environment, activity of cortical neurons is regulated by neuromodulators such as Acetylcholine (ACh). As such, ACh is implicated in cognitive functions including attention, arousal and sleep cycles. However, it is not clear how specific ACh receptors shape the baseline activity of cortical neurons and their evoked response to sensory stimuli. Here, we investigate the role of a densely expressed muscarinic ACh receptor 1 (M1) in information processing in the mouse primary somatosensory cortex (vS1) and in the animal’s sensitivity in detecting vibrotactile stimuli. We show that M1 activation significantly enhances the evoked response of vS1 neurons and the reversal of this enhancement by blocking M1. In addition, we demonstrate that M1 activation results in faster and more reliable neuronal responses, which is manifested by a significant reduction in response latencies and the trial-to-trial variability in neuronal activity. At the population level, M1 activation reduces the network synchrony and thus enhances the capacity of vS1 neurons in conveying sensory information. Consistent with the neuronal findings, we show that M1 activation significantly improves performances in a vibrotactile detection task. Overall, the M1-mediated enhancement in sensory efficiency reflects a multiplicative gain modulation at the neuronal level, resembling the changes observed during high attention states.
Dynamics of pre- and post-choice behaviour: rats approximate optimal strategy in a discrete-trial decision task
Publisher: The Royal Society
Date: 22-03-2015
Abstract: We simulate two types of environments to investigate how closely rats approximate optimal foraging. Rats initiated a trial where they chose between two spouts for sucrose, which was delivered at distinct probabilities. The discrete trial procedure used allowed us to observe the relationship between choice proportions, response latencies and obtained rewards. Our results show that rats approximate the optimal strategy across a range of environments that differ in the average probability of reward as well as the dynamics of the depletion-renewal cycle. We found that the constituent components of a single choice differentially reflect environmental contingencies. Post-choice behaviour, measured as the duration of time rats spent licking at the spouts on unrewarded trials, was the most sensitive index of environmental variables, adjusting most rapidly to changes in the environment. These findings have implications for the role of confidence in choice outcomes for guiding future choices.
Visual conscious awareness depends on a temporary filter based on representational similarity
Publisher: Research Square Platform LLC
Date: 08-12-2022
DOI: 10.21203/RS.3.RS-2318730/V1
Abstract: Our visual perception seems effortless, but the brain has a limited processing capacity which curtails the amount of sensory information that can be brought into conscious awareness at any moment in time. A widely studied exemplar of this limitation is the ‘attentional blink’ (AB), in which observers are unable to report the second of two rapidly sequential targets if it appears within 200-500 ms of the first. Despite the apparent ubiquity of the AB effect, its computational and neurophysiological underpinnings have remained elusive. Here we propose a simple computational model of temporal attention that unifies the AB with spatial and feature-based attention. We took a novel, integrative approach involving human psychophysics and functional brain imaging, along with neuronal recordings in mice to test this model. Specifically, we demonstrate that the AB only arises when visual targets have dissimilar representations in the brain but is absent when both targets have the same representation. Similarity in this context can be determined either by elementary features such as edge orientation, or by acquired, high-level factors such as numerical or alphabetical order. In this parsimonious model of the AB, attention to an initial target establishes a perceptual filter that is tuned to its unique representation in the brain. Subsequent items that match the filter remain available for conscious report, whereas those that do not match elude awareness altogether.
Occupational and environmental risk factors for idiopathic pulmonary fibrosis in Australia: case-control study
Publisher: BMJ
Date: 13-07-2020
DOI: 10.1136/THORAXJNL-2019-214478
Abstract: Idiopathic pulmonary fibrosis (IPF) is a lung disease of unknown cause characterised by progressive scarring, with limited effective treatment and a median survival of only 2–3 years. Our aim was to identify potential occupational and environmental exposures associated with IPF in Australia. Cases were recruited by the Australian IPF registry. Population-based controls were recruited by random digit dialling, frequency matched on age, sex and state. Participants completed a questionnaire on demographics, smoking, family history, environmental and occupational exposures. Occupational exposure assessment was undertaken with the Finnish Job Exposure Matrix and Australian asbestos JEM. Multivariable logistic regression was used to describe associations with IPF as ORs and 95% CIs, adjusted for age, sex, state and smoking. We recruited 503 cases (mean±SD age 71±9 years, 69% male) and 902 controls (71±8 years, 69% male). Ever smoking tobacco was associated with increased risk of IPF: OR 2.20 (95% CI 1.74 to 2.79), but ever using marijuana with reduced risk after adjusting for tobacco: 0.51 (0.33 to 0.78). A family history of pulmonary fibrosis was associated with 12.6-fold (6.52 to 24.2) increased risk of IPF. Occupational exposures to secondhand smoke (OR 2.1 1.2 to 3.7), respirable dust (OR 1.38 1.04 to 1.82) and asbestos (OR 1.57 1.15 to 2.15) were independently associated with increased risk of IPF. However occupational exposures to other specific organic, mineral or metal dusts were not associated with IPF. The burden of IPF could be reduced by intensified tobacco control, occupational dust control measures and elimination of asbestos at work.
Shifts in Coding Properties and Maintenance of Information Transmission during Adaptation in Barrel Cortex
Publisher: Public Library of Science (PLoS)
Date: 23-01-2007
Informational Basis of Sensory Adaptation: Entropy and Single-Spike Efficiency in Rat Barrel Cortex
Publisher: Society for Neuroscience
Date: 11-09-2013
DOI: 10.1523/JNEUROSCI.1313-13.2013
Abstract: We showed recently that exposure to whisker vibrations enhances coding efficiency in rat barrel cortex despite increasing correlations in variability (Adibi et al., 2013). Here, to understand how adaptation achieves this improvement in sensory representation, we decomposed the stimulus information carried in neuronal population activity into its fundamental components in the framework of information theory. In the context of sensory coding, these components are the entropy of the responses across the entire stimulus set (response entropy) and the entropy of the responses conditional on the stimulus (conditional response entropy). We found that adaptation decreased response entropy and conditional response entropy at both the level of single neurons and the pooled activity of neuronal populations. However, the net effect of adaptation was to increase the mutual information because the drop in the conditional entropy outweighed the drop in the response entropy. The information transmitted by a single spike also increased under adaptation. As population size increased, the information content of in idual spikes declined but the relative improvement attributable to adaptation was maintained.
Single tactile afferents outperform human subjects in a vibrotactile intensity discrimination task
Publisher: American Physiological Society
Date: 15-11-2014
Abstract: We simultaneously compared the sensitivity of single primary afferent neurons supplying the glabrous skin of the hand and the psychophysical litude discrimination thresholds in human subjects for a set of vibrotactile stimuli delivered to the receptive field. All recorded afferents had a dynamic range narrower than the range of litudes across which the subjects could discriminate. However, when the vibration litude was chosen to be within the steepest part of the afferent's stimulus-response function the response of single afferents, defined as the spike count over the vibration duration (500 ms), was often more sensitive in discriminating vibration litude than the perceptual judgment of the participants. We quantified how the neuronal performance depended on the integration window: for short windows the neuronal performance was inferior to the performance of the subject. The neuronal performance progressively improved with increasing spike count duration and reached a level significantly above that of the subjects when the integration window was 250 ms or longer. The superiority in performance of in idual neurons over observers could reflect a nonoptimal integration window or be due to the presence of noise between the sensory periphery and the cortical decision stage. Additionally, it could indicate that the range of perceptual sensitivity comes at the cost of discrimination through pooling across neurons with different response functions.
Sensory prediction errors increase coding efficiency in mouse visual cortex through gain amplification
Publisher: Research Square Platform LLC
Date: 08-12-2021
DOI: 10.21203/RS.3.RS-1136564/V1
Abstract: The efficiency of sensory coding is affected both by past events (adaptation) and by expectation of future events (prediction). Here we employed a novel visual stimulus paradigm to determine whether expectation influences orientation selectivity in the primary visual cortex. We used two-photon calcium imaging (GCaMP6f) in awake mice viewing visual stimuli with different levels of predictability. The stimuli consisted of sequences of grating stimuli that randomly shifted in orientation or systematically rotated with occasionally unexpected rotations. At the single neuron and population level, there was significantly enhanced orientation-selective response to unexpected visual stimuli through a boost in gain, which was prominent in awake mice but also present to a lesser extent under anesthesia. We implemented a computational model to demonstrate how neuronal responses were best characterized when adaptation and expectation parameters were combined. Our results demonstrated that adaptation and prediction have unique signatures on activity of V1 neurons.
Localized two-photon photoswitching of Optovin in rat cortical neurons
Publisher: IOP Publishing
Date: 12-04-2019
Spike-timing in primary sensory neurons: a model of somatosensory transduction in the rat
Publisher: Springer Science and Business Media LLC
Date: 05-01-2008
DOI: 10.1007/S00422-007-0208-7
Abstract: In previous work, we constructed a simple electro-mechanical model of transduction in the rat mystacial follicle that was able to replicate primary afferent response profiles to a variety of whisker deflection stimuli. Here, we update that model to fit newly available spike-timing response data, and demonstrate that the new model produces appropriate responses to richer stimuli, including pseudo white noise and natural textures, at a spike-timing level of detail. Additionally, we demonstrate reliable distributed encoding of multi-component oscillatory signals. No modifications were necessary to the mechanical model of the physical components of the follicle-sinus complex, supporting its generality. We conclude that this model, and its continued development, will aid the understanding both of somatosensory systems in general, and of physiological results from higher (e.g. thalamocortical) systems by accurately characterising the signals on which they operate.
State-Dependent Changes in Perception and Coding in the Mouse Somatosensory Cortex
Publisher: Elsevier BV
Date: 09-2020
Expectation violations enhance neuronal encoding of sensory information in mouse primary visual cortex
Publisher: Springer Science and Business Media LLC
Date: 02-03-2023
DOI: 10.1038/S41467-023-36608-8
Abstract: The response of cortical neurons to sensory stimuli is shaped both by past events (adaptation) and the expectation of future events (prediction). Here we employed a visual stimulus paradigm with different levels of predictability to characterise how expectation influences orientation selectivity in the primary visual cortex (V1) of male mice. We recorded neuronal activity using two-photon calcium imaging (GCaMP6f) while animals viewed sequences of grating stimuli which either varied randomly in their orientations or rotated predictably with occasional transitions to an unexpected orientation. For single neurons and the population, there was significant enhancement in the gain of orientation-selective responses to unexpected gratings. This gain-enhancement for unexpected stimuli was prominent in both awake and anaesthetised mice. We implemented a computational model to demonstrate how trial-to-trial variability in neuronal responses were best characterised when adaptation and expectation effects were combined.
Temporal dynamics of choice behavior in rats and humans: an examination of pre- and post-choice latencies
Publisher: Springer Science and Business Media LLC
Date: 10-02-2016
DOI: 10.1038/SREP20583
Abstract: Identifying similarities and differences in choice behavior across species is informative about how basic mechanisms give rise to more complex processes. In the present study, we compared pre- and post-choice latencies between rats and humans under two paradigms. In Experiment 1, we used a cued choice paradigm where subjects were presented with a cue that directed them as to which of two options to respond for rewards. In Experiment 2, subjects were free to choose between two options in order to procure rewards. In both Experiments rewards were delivered with distinct probabilities. The trial structure used in these experiments allowed the choice process to be decomposed into pre- and post-choice processes. Overall, post-choice latencies reflected the difference in reward probability between the two options, where latencies for the option with higher probability of reward were longer than those for the option with lower probability of reward. An interesting difference between rats and humans was observed: the choice behavior for humans, but not rats, was sensitive to the free-choice aspect of the tasks, such that in free-choice trials post-choice latencies no longer reflected the difference in reward probabilities between the two options.
Diverse tuning underlies sparse activity in L2/3 vibrissal cortex of awake mice
Publisher: Cold Spring Harbor Laboratory
Date: 31-10-2018
DOI: 10.1101/457796
Abstract: It is widely reported that superficial layers of the somatosensory cortex exhibit sparse firing. This sparseness could reflect weak feedforward sensory inputs that are not sufficient to generate action potentials in these layers. Alternatively, sparseness might reflect tuning to unknown or higher-level complex features that are not fully explored in the stimulus space. Here, we examined these hypotheses by applying a range of vibrotactile and manual vibrissal stimuli in awake, head-fixed mice while performing loose-seal cell-attached recordings from the vibrissal primary somatosensory (vS1) cortex. A high-velocity stimulus delivered by a piezo-electric actuator evoked activity in a small fraction of regular spiking supragranular neurons (29%) in awake condition. However, a majority of the supragranular regular spiking neurons (84%) were driven by manual stimulation of whiskers. Our results suggest that most neurons in the superficial layers of vS1 cortex contribute to coding in awake conditions when neurons may encounter their preferred feature(s) during whisker-object interactions.
Whisker Vibration Information Carried by Rat Barrel Cortex Neurons
Publisher: Society for Neuroscience
Date: 30-06-2004
DOI: 10.1523/JNEUROSCI.1389-04.2004
Abstract: Rats can make extremely fine texture discriminations by “whisking” their vibrissa across the surface of an object. We have investigated one hypothesis for the neuronal basis of texture representation by measuring how clusters of neurons in the barrel cortex of anesthetized rats encode the kinetic features of sinusoidal whisker vibrations. Mutual information analyses of spike counts led to a number of findings. Information about vibration kinetics became available as early as 6 msec after stimulus onset and reached a peak at ∼20-30 msec. Vibration speed, proportional to the product of vibration litude ( A ) and frequency ( f ), was the kinetic property most reliably reported by cortical neurons. Indeed, by measuring information when the complete stimulus set was collapsed into feature-defined groups, we found that neurons reduced the dimensionality of the stimulus from two features ( A, f ) to a single feature, the product Af . Moreover, because different neurons encode stimuli in the same manner, information loss was negligible even when the activity of separate neuronal clusters was pooled. This suggests a decoding scheme whereby target neurons could capture all available information simply by summating the signals from separate barrel cortex neurons. These results indicate that neuronal population activity provides sufficient information to allow nearly perfect discrimination of two vibrations, based on their deflection speeds, within a time scale comparable with that of a single whisking motion across a surface.
Accurate and rapid estimation of phosphene thresholds (REPT).
Publisher: Public Library of Science (PLoS)
Date: 22-07-2011
Behavioural correlate of choice confidence in a discrete trial paradigm.
Publisher: Public Library of Science (PLoS)
Date: 27-10-2011
New attractor states for synchronous activity in synfire chains with excitatory and inhibitory coupling
Publisher: Springer Science and Business Media LLC
Date: 05-2002
DOI: 10.1007/S00422-001-0293-Y
Abstract: In a feedforward network of integrate-and-fire neurons, where the firing of each layer is synchronous (synfire chain), the final firing state of the network converges to two attractor states: either a full activation or complete fading of the tailing layers. In this article, we analyze various modes of pattern propagation in a synfire chain with random connection weights and delta-type postsynaptic currents. We predict analytically that when the input is fully synchronized and the network is noise free, varying the characteristics of the weights distribution would result in modes of behavior that are different from those described in the literature. These are convergence to fixed points, limit cycles, multiple periodic, and possibly chaotic dynamics. We checked our analytic results by computer simulation of the network, and showed that the above results can be generalized when the input is asynchronous and neurons are spontaneously active at low rates.
A good bet to measure awareness?
Publisher: Elsevier BV
Date: 06-2008
Texture Signals in Whisker Vibrations
Publisher: American Physiological Society
Date: 03-2006
Abstract: Rodents excel in making texture judgments by sweeping their whiskers across a surface. Here we aimed to identify the signals present in whisker vibrations that give rise to such fine sensory discriminations. First, we used sensors to capture vibration signals in metal whiskers during active whisking of an artificial system and in natural whiskers during whisking of rats in vivo. Then we developed a classification algorithm that successfully matched the vibration frequency spectra of single trials to the texture that induced it. For artificial whiskers, the algorithm correctly identified one texture of eight alternatives on 40% of trials for in vivo natural whiskers, the algorithm correctly identified one texture of five alternatives on 80% of trials. Finally, we asked which were the key discriminative features of the vibration spectra. Under both artificial and natural conditions, the combination of two features accounted for most of the information: The modulation power—the power of the part of the whisker movement representing the modulation due to the texture surface—increased with the coarseness of the texture the modulation centroid—a measure related to the center of gravity within the power spectrum—decreased with the coarseness of the texture. Indeed, restricting the signal to these two parameters led to performance three-fourths as high as the full spectra. Because earlier work showed that modulation power and centroid are directly related to neuronal responses in the whisker pathway, we conclude that the biological system optimally extracts vibration features to permit texture classification.
Behavioral study of whisker-mediated vibration sensation in rats
Publisher: Proceedings of the National Academy of Sciences
Date: 04-01-2012
Abstract: Rats use their vibrissal sensory system to collect information about the nearby environment. They can accurately and rapidly identify object location, shape, and surface texture. Which features of whisker motion does the sensory system extract to construct sensations? We addressed this question by training rats to make discriminations between sinusoidal vibrations simultaneously presented to the left and right whiskers. One set of rats learned to reliably identify which of two vibrations had higher frequency ( f 1 vs. f 2 ) when litudes were equal. Another set of rats learned to reliably identify which of two vibrations had higher litude ( A 1 vs. A 2 ) when frequencies were equal. Although these results indicate that both elemental features contribute to the rats’ sensation, a further test found that the capacity to discriminate A and f was reduced to chance when the difference in one feature was counterbalanced by the difference in the other feature: Rats could not discriminate litude or frequency whenever A 1 f 1 = A 2 f 2 . Thus, vibrations were sensed as the product Af rather than as separable elemental features, A and f . The product Af is proportional to a physical entity, the mean speed. Analysis of performance revealed that rats extracted more information about differences in Af than predicted by the sum of the information in elemental differences. These behavioral experiments support the predictions of earlier physiological studies by demonstrating that rats are “blind” to the elemental features present in a sinusoidal whisker vibration instead, they perceive a composite feature, the speed of whisker motion.
Characterization of the T-cell epitopes of a major peanut allergen, Ara h 2
Publisher: Wiley
Date: 02-11-2005
Dynamics of Population Activity in Rat Sensory Cortex: Network Correlations Predict Anatomical Arrangement and Information Content
Publisher: Frontiers Media SA
Date: 06-07-2016
Correlated physiological and perceptual effects of noise in a tactile stimulus
Publisher: Proceedings of the National Academy of Sciences
Date: 12-04-2010
Abstract: We investigated connections between the physiology of rat barrel cortex neurons and the sensation of vibration in humans. One set of experiments measured neuronal responses in anesthetized rats to trains of whisker deflections, each train characterized either by constant litude across all deflections or by variable litude (“ litude noise”). Firing rate and firing synchrony were, on average, boosted by the presence of noise. However, neurons were not uniform in their responses to noise. Barrel cortex neurons have been categorized as regular-spiking units (putative excitatory neurons) and fast-spiking units (putative inhibitory neurons). Among regular-spiking units, litude noise caused a higher firing rate and increased cross-neuron synchrony. Among fast-spiking units, noise had the opposite effect: It led to a lower firing rate and decreased cross-neuron synchrony. This finding suggests that litude noise affects the interaction between inhibitory and excitatory neurons. From these physiological effects, we expected that noise would lead to an increase in the perceived intensity of a vibration. We tested this notion using psychophysical measurements in humans. As predicted, subjects overestimated the intensity of noisy vibrations. Thus the physiological mechanisms present in barrel cortex also appear to be at work in the human tactile system, where they affect vibration perception.
Vision Merges With Touch in a Purely Tactile Discrimination
Publisher: SAGE Publications
Date: 07-2008
DOI: 10.1111/J.1467-9280.2008.02134.X
Abstract: To construct a coherent percept of the world, the brain continuously combines information across multiple sensory modalities. Simple stimuli from different modalities are usually assumed to be processed in distinct brain areas. However, there is growing evidence that simultaneous stimulation of multiple modalities can influence the activity in unimodal sensory areas and improve or impair performance in unimodal tasks. Do these effects reflect a genuine cross-modal integration of sensory signals, or are they due to changes in the perceiver's ability to locate the stimulus in time and space? We used a behavioral measure to differentiate between these explanations. Our results demonstrate that, under certain circumstances, a noninformative flash of light can have facilitative or detrimental effects on a simple tactile discrimination. The effect of the visual flash mimics that produced by a constant tactile pedestal stimulus. These findings reveal that sensory signals from different modalities can be integrated, even for perceptual judgments within a single modality.
Enhanced sensory coding in mouse vibrissal and visual cortex through TRPA1
Publisher: Cold Spring Harbor Laboratory
Date: 20-12-2019
DOI: 10.1101/2019.12.19.881896
Abstract: Transient Receptor Potential Ankyrin 1 (TRPA1) is a non-selective cation channel, which is broadly expressed throughout the body. Despite its expression in the mammalian cortex, little is known about the contribution of TRPA1 to cortical function. Here we investigate the role of TRPA1 in sensory information processing by performing electrophysiological recording and 2-photon calcium imaging from two sensory areas in mice: the primary vibrissal somatosensory cortex (vS1) and the primary visual cortex (V1). In vS1, local activation of TRPA1 by its agonist AITC significantly increased the spontaneous activity of cortical neurons, their evoked response to vibrissal stimulation, and their response range, consistent with a positive gain modulation. TRPA1 inhibition with HC-030031 reversed these modulations to below initial control gains. The gain modulations were absent in TRPA1 Knockout mice. In V1, TRPA1 activation increased the gain of direction and orientation selectivity similarly to the gain modulations observed in vS1 cortex. Linear decoding analysis of V1 population activity confirmed faster and more reliable encoding of visual signals in the presence of TRPA1 activation. Overall, our findings reveal a physiological role for TRPA1 in enhancing sensory signals in the mammalian cortex.
Neural dynamics of the attentional blink revealed by encoding orientation selectivity during rapid visual presentation
Publisher: Springer Science and Business Media LLC
Date: 23-01-2020
DOI: 10.1038/S41467-019-14107-Z
Abstract: The human brain is inherently limited in the information it can make consciously accessible. When people monitor a rapid stream of visual items for two targets, they typically fail to see the second target if it occurs within 200–500 ms of the first, a phenomenon called the attentional blink (AB). The neural basis for the AB is poorly understood, partly because conventional neuroimaging techniques cannot resolve visual events displayed close together in time. Here we introduce an approach that characterises the precise effect of the AB on behaviour and neural activity. We employ multivariate encoding analyses to extract feature-selective information carried by randomly-oriented gratings. We show that feature selectivity is enhanced for correctly reported targets and suppressed when the same items are missed, whereas irrelevant distractor items are unaffected. The findings suggest that the AB involves both short- and long-range neural interactions between visual representations competing for access to consciousness.
High-velocity stimulation evokes “dense” population response in layer 2/3 vibrissal cortex
Publisher: American Physiological Society
Date: 03-2017
Abstract: Supragranular layers of sensory cortex are known to exhibit sparse firing. In rodent vibrissal cortex, a small fraction of neurons in layer 2 and 3 (L2/3) respond to whisker stimulation. In this study, we combined whole cell recording and two-photon imaging in anesthetized mice and quantified the synaptic response and spiking profile of L2/3 neurons. Previous literature has shown that neurons across layers of vibrissal cortex are tuned to the velocity of whisker movement. We therefore used a broad range of stimuli that included the standard range of velocities (0–1.2 deg/ms) and extended to a “sharp” high-velocity deflection (3.8 deg/ms). Consistent with previous literature, whole cell recording revealed a sparse response to the standard range of velocities: although all recorded cells showed tuning to velocity in their postsynaptic potentials, only a small fraction produced stimulus-evoked spikes. In contrast, the sharp stimulus evoked reliable spiking in the majority of neurons. The action potential threshold of spikes evoked by the sharp stimulus was significantly lower than that of the spontaneous spikes. Juxtacellular recordings confirmed that application of sharp stimulus to single or multiple whiskers produced temporally precise spiking with minimal trial-to-trial spike count variability (Fano factors equal or close to the theoretical minimum). Two-photon imaging further confirmed that most neurons that were not responsive to the standard deflections responded to the sharp stimulus. Altogether, our results indicate that sparseness in L2/3 cortex depends on the choice of stimulus: strong single- or multiwhisker stimulation can induce the transition from sparse to “dense” population response. NEW & NOTEWORTHY In superficial layers of sensory cortex, only a small fraction of neurons fire most of the spontaneous and sensory evoked spikes. However, the functional relevance of such “sparse” activity remains unknown. We found that a “dense” population response is evoked by high-velocity micromotions applied to whiskers. Our results suggest that flashes of precisely timed population response on an almost silent background can provide a high capacity for coding of ecologically salient stimuli.
Low Intensity TMS Enhances Perception of Visual Stimuli
Publisher: Elsevier BV
Date: 11-2015
DOI: 10.1016/J.BRS.2015.06.012
Abstract: Transcranial magnetic stimulation (TMS) is a popular functional mapping tool in cognitive and sensory neuroscience. While strong TMS typically degrades performance, two recent studies have demonstrated that weak TMS, delivered to visual cortex, can improve performance on simple visual tasks. The improvement was interpreted as the summation of visually-evoked and TMS-elicited neuronal activity in visual cortex, but the nature of this interaction remains unclear. The present experiments sought to determine whether these weak pulses of TMS assist subjects to see the visual stimulus itself or create a distinct "melded" percept that may not be recognizable as the visual stimulus. We measured contrast thresholds in an orientation discrimination task in which participants reported the orientation (left or right) of gratings tilted 45° from vertical. Weak TMS improved sensitivity for identifying gratings, suggesting that TMS sums with but preserves orientation information so that the subject can recognize the visual stimulus. We explain the effect using a mechanism of non-linear transduction of sensory signals in the brain. The capability of low-intensity TMS to augment the neural signal while preserving information encoded in the stimulus can be employed as a novel approach to study the neural correlates of consciousness by selectively "pushing" an unconscious stimulus into consciousness.
Neuronal Encoding of Natural Stimuli: The Rat Tactile System
Publisher: Wiley
Date: 13-01-2006
Improving Visual Sensitivity with Subthreshold Transcranial Magnetic Stimulation
Publisher: Society for Neuroscience
Date: 02-03-2011
DOI: 10.1523/JNEUROSCI.6256-10.2011
Abstract: We probed for improvement of visual sensitivity in human participants using transcranial magnetic stimulation (TMS). Stimulation of visual cortex can induce an illusory visual percept known as a phosphene. It is known that TMS, delivered at intensities above the threshold to induce phosphenes, impairs the detection of visual stimuli. We investigated how the detection of a simple visual stimulus is affected by TMS applied to visual cortex at or below the phosphene threshold. Participants performed the detection task while the contrast of the visual stimulus was varied from trial to trial according to an adaptive staircase procedure. Detection of the stimulus was enhanced when a single pulse of TMS was delivered to the contralateral visual cortex 100 or 120 ms after stimulus onset at intensities just below the phosphene threshold. No improvement in visual sensitivity was observed when TMS was applied to the visual cortex in the opposite hemisphere (ipsilateral to the visual stimulus). We conclude that TMS-induced neuronal activity can sum with stimulus-evoked activity to augment visual perception.
Information Processing Across Behavioral States: Modes of Operation and Population Dynamics in Rodent Sensory Cortex
Publisher: Elsevier BV
Date: 2018
DOI: 10.1016/J.NEUROSCIENCE.2017.09.016
Abstract: Animals live in a complex and changing environment with various degrees of behavioral demands. In rodents, the behavioral states can change from sleep and quiet wakefulness to active exploration of the environment which is often manifested by whisking and locomotion. Efficient information processing is more important in some of these behavioral states such as during episodes of sensory decision-making, and specific cortical areas are expected to receive priority of processing depending on the behavioral context. It is therefore not surprising that the behavioral state affects the responsiveness of in idual cortical neurons and the dynamics of neuronal population activity. Here, we review the circuit mechanisms that determine the operating mode of the sensory cortex. We explore state modulations across multiple sensory modalities, but maintain a focus on whisker-mediated behaviors, the processing of information in the vibrissal somatosensory cortex and its transfer to higher order areas. Finally, we suggest a rodent sensory prioritization paradigm to further probe the link between behavioral state, neuronal population dynamics and coding efficiency.
Diverse tuning underlies sparse activity in layer 2/3 vibrissal cortex of awake mice
Publisher: Wiley
Date: 16-04-2019
DOI: 10.1113/JP277506
Related Organisations
Tehran University Of Medical Sciences
Location: Iran (Islamic Republic of)
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