ORCID Profile
0000-0002-2968-7358
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UNSW Australia
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Sensory Processes, Perception and Performance | Sensory Systems | Neurosciences | Peripheral Nervous System
Expanding Knowledge in the Biological Sciences | Expanding Knowledge in Psychology and Cognitive Sciences |
Publisher: Springer International Publishing
Date: 2018
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 03-1997
DOI: 10.1097/00001756-199703240-00041
Abstract: We investigated the corticocortical connections between area 21a and ipsilateral areas 17 and 18 in the cat. The anterograde/retrograde fluorescent tracer tetramethyl-rhodamine conjugated to dextran (Fluoro-Ruby) was injected into area 21a of the anaesthetized cat. Cell bodies labelled retrogradely from area 21a were consistently observed in both areas 17 and 18, primarily located in the supragranular layers of cortex where they formed discrete patches of cells. Similar numbers of cell bodies were labelled retrogradely in areas 17 and 18 of each animal. Our data are also consistent with previous reports of a reciprocal projection from area 21a back to areas 17 and 18 terminating principally in infragranular cortical layers.
Publisher: Springer Science and Business Media LLC
Date: 1993
DOI: 10.1007/BF00228402
Abstract: The cervix undergoes extensive remodeling throughout pregnancy and parturition. This process involves both ECM collagen degradation and cellular remodeling, which includes cell proliferation, transition and migration. Progesterone (P4) has been used clinically to delay cervical ripening and prevent preterm birth (PTB). However, the mechanisms by which progesterone affects cell transition and the migration of cervical epithelial and stromal cells are not yet fully known. In this study, we documented the role of a gestational level of P4 in the cellular transition (epithelial-mesenchymal transition [EMT] and mesenchymal-epithelial transition [MET]), cell migration, and inflammatory responses of endocervical epithelial cells (EEC) and cervical stromal cells (CSC). EEC and CSC were treated with LPS and P4 for 6 days. The epithelial:mesenchymal ratio (regular microscopy and cell shape index analysis), shift in intermediate filaments (immunofluorescence microscopy and western blot analyses for cytokeratin [CK]-18 and vimentin), adhesion molecules and transcription factors (western blot analyses for E-cadherin, N-cadherin and SNAIL), were used to determine growth characteristics and EMT and MET changes in EEC and CSC under the indicated conditions. To test cell remodeling, scratch assays followed by cellular analyses as mentioned above were performed. Inflammatory cytokines (interleukin-6 [IL-6], tumor necrosis factor α [TNFα]) and matrix metallopeptidase 9 (MMP9) were measured by ELISA. LPS promoted EMT (decreased cell shape index, decreased CK-18 and E-cadherin, increased vimentin, N-cadherin, and SNAIL), and increased IL-6 and MMP9 production by EEC. A gestational level of P4 prevented LPS-induced EMT in EEC and exhibited anti-inflammatory effect in both EEC and CSC. LPS slowed down wound healing in CSC but P4 treatment prevented the negative impact of LPS in CSC wound healing. These results may explain the cellular mechanisms by which P4 helps to stabilize the cervical epithelial barrier and preserve the mechanical and tensile strength of the cervical stromal layer, which are important in normal cervical remodeling processes during pregnancy.
Publisher: Springer Science and Business Media LLC
Date: 12-1992
DOI: 10.1007/BF00227971
Publisher: MIT Press - Journals
Date: 05-11-2021
DOI: 10.1162/JOCN_A_01747
Abstract: Sensory suppression refers to the phenomenon that sensory input generated by our own actions, such as moving a finger to press a button to hear a tone, elicits smaller neural responses than sensory input generated by external agents. This observation is usually explained via the internal forward model in which an efference copy of the motor command is used to compute a corollary discharge, which acts to suppress sensory input. However, because moving a finger to press a button is accompanied by neural processes involved in preparing and performing the action, it is unclear whether sensory suppression is the result of movement planning, movement execution, or both. To investigate this, in two experiments, we compared ERPs to self-generated tones that were produced by voluntary, semivoluntary, or involuntary button-presses, with externally generated tones that were produced by a computer. In Experiment 1, the semivoluntary and involuntary button-presses were initiated by the participant or experimenter, respectively, by electrically stimulating the median nerve in the participant's forearm, and in Experiment 2, by applying manual force to the participant's finger. We found that tones produced by voluntary button-presses elicited a smaller N1 component of the ERP than externally generated tones. This is known as N1-suppression. However, tones produced by semivoluntary and involuntary button-presses did not yield significant N1-suppression. We also found that the magnitude of N1-suppression linearly decreased across the voluntary, semivoluntary, and involuntary conditions. These results suggest that movement planning is a necessary condition for producing sensory suppression. We conclude that the most parsimonious account of sensory suppression is the internal forward model.
Publisher: Wiley
Date: 02-1994
DOI: 10.1113/JPHYSIOL.1994.SP020030
Abstract: 1. The synaptic linkage between single, identified slowly adapting type I (SAI) fibres and their central target neurones of the cuneate nucleus was examined in pentobarbitone-anaesthetized cats. Simultaneous extracellular recordings were made from in idual cuneate neurones and from fine, intact fascicles of the lateral branch of the superficial radial nerve in which it was possible to identify and monitor the activity of each group II fibre. In idual SAI fibres were activated by static displacement and by vibration delivered with a fine probe (0.25-2 mm diameter) to their associated touch domes in the hairy skin of the forelimb. 2. Transmission properties across the synapse were analysed for nine SAI-cuneate pairs in which the single SAI fibre of each pair provided a suprathreshold input to the cuneate neurone. Neither spatial nor temporal summation was required for effective impulse transmission, and often more than 80% of SAI impulses led to a response in the cuneate neurone. Responses of the cuneate neurones to single SAI impulses occurred at a short, fixed latency (S.D. often 100-150 Hz despite 1:1 responses in their single SAI input fibres up to approximately 500 Hz. 4. The reliable transmission of touch dome-associated SAI input across the cuneate nucleus indicates that transmission failure at this first relay is unlikely to be responsible for the reported failure of touch dome-SAI inputs to contribute to tactile perception. 5. The transmission characteristics for the SAI fibres were very similar to those demonstrated previously for fibres associated with Pacinian corpuscles, which argues against any marked differential specialization in transmission characteristics for dorsal column nuclei neurones that receive input from different tactile fibre classes.
Publisher: Wiley
Date: 12-1992
DOI: 10.1113/JPHYSIOL.1992.SP019411
Abstract: 1. Slowly adapting type II (SAII) afferent fibres that supply the forelimb were isolated from the medial cutaneous nerve of anaesthetized cats and examined for their capacity to signal information about vibrotactile events in the hairy skin. 2. The SAII fibres had a single spot-like receptive field focus where they were highly sensitive to steady indentation and vibration applied with probes normal to the skin surface. However, their sensitivity was affected profoundly by the size of the stimulus probe, its position in relation to the receptive field focus and, to a lesser extent, the magnitude of any pre-indentation on which vibration was superimposed. Small stimulus probes (e.g. 250 microns diameter) were much more effective than larger (> or = 1-2 mm) ones, and small shifts in the position of the perpendicularly applied probe away from the receptive field focus led to a marked decline in responsiveness. 3. With appropriate choice of stimulus parameters for vibratory stimuli applied at the receptive field focus, the SAII fibres could respond at low threshold (< 100 microns), with a tightly phase-locked, regular 1:1 impulse pattern (one impulse per vibration cycle) that accurately signalled the vibration frequency over a bandwidth that extended to 600 Hz. Furthermore, their responses remained phase-locked up to 1000 Hz. Phase-locking in SAII fibres was marginally tighter than that in SAI fibres and comparable to that of Pacinian corpuscle fibres. 4. The sensitivity of forelimb SAII fibres to tangential skin stretch was directionally selective stretch across the forelimb was much more effective than along its long axis. Vibration associated with tangential skin stretch led to a marked spatial expansion of the field of vibration sensitivity. SAII fibres could therefore signal information about natural stimuli that contain elements of skin stretch and vibration, as may be encountered when the forelimb brushes against textured surfaces. Should the SAII fibres fail to contribute to the sensory experience of vibrotactile stimuli, the explanation may be related to limitations imposed centrally on the processing of their signals. Nevertheless, the present results demonstrate that, with appropriate stimulus conditions, the SAII afferent fibres have much greater vibrotactile sensitivity than has been suggested by past studies.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: American Physiological Society
Date: 03-2021
Abstract: This study contributes to understanding how frictional information is obtained and used by the brain. When the skin is contacting surfaces of identical topography but varying frictional properties, the deformation pattern is different however, available sensory cues did not get translated into perception of frictional properties unless a sufficiently large lateral movement was present. These neurophysiological findings may inform how to design and operate haptic devices relying on friction modulation principles.
Publisher: American Physiological Society
Date: 03-2016
Abstract: Neurophysiological studies in primates have found that direction-sensitive neurons in the primary somatosensory cortex (SI) generally increase their response rate with increasing speed of object motion across the skin and show little evidence of speed tuning. We employed psychophysics to determine whether human perception of motion direction could be explained by features of such neurons and whether evidence can be found for a speed-tuned process. After adaptation to motion across the skin, a subsequently presented dynamic test stimulus yields an impression of motion in the opposite direction. We measured the strength of this tactile motion aftereffect (tMAE) induced with different combinations of adapting and test speeds. Distal-to-proximal or proximal-to-distal adapting motion was applied to participants' index fingers using a tactile array, after which participants reported the perceived direction of a bidirectional test stimulus. An intensive code for speed, like that observed in SI neurons, predicts greater adaptation (and a stronger tMAE) the faster the adapting speed, regardless of the test speed. In contrast, speed tuning of direction-sensitive neurons predicts the greatest tMAE when the adapting and test stimuli have matching speeds. We found that the strength of the tMAE increased monotonically with adapting speed, regardless of the test speed, showing no evidence of speed tuning. Our data are consistent with neurophysiological findings that suggest an intensive code for speed along the motion processing pathways comprising neurons sensitive both to speed and direction of motion.
Publisher: IOP Publishing
Date: 04-2008
DOI: 10.1088/1741-2560/5/2/003
Abstract: Using a multi-channel platinum surface electrode array, recordings from cat primary visual cortex were obtained in response to visual stimuli, and electrical stimuli delivered using the elements of the array itself. Neural responses to electrical stimuli were consistent, regardless of stimulus polarity or leading phase (biphasic), although thresholds were lower for monophasic than biphasic pulses. Both visual and electrical stimuli reliably evoked responses with characteristic components, which interacted with each other in a nonlinear summation showing first facilitation then suppression during the window of interaction. The chronaxie for eliciting threshold cortical responses was about 100 mus, and the charge density with a pulse width of 50-100 mus was around 55 muC cm(-2). These data form the basis of understanding the types of cortical responses to stimuli delivered by devices suitable for chronic implantation.
Publisher: Springer Science and Business Media LLC
Date: 04-05-2002
DOI: 10.1007/S00221-002-1108-7
Abstract: We have used information theory to analyse the responses of neurons in area 21a of the cat to disparity stimuli. Visual stimuli consisted of drifting sinusoidal gratings presented simultaneously to each eye. The relative spatial phase of the gratings varied between stimulus periods in a pseudo-random sequence of 45 degrees increments that covered the full 360 degrees. The mean information content of the responses of all neurons across all phases was 0.72 bits (+/-0.10, SE, n=29). The information conveyed by each neuron was well correlated with the extent to which the interocular phase difference modulated the response of the cell. However, information content was not simply related to firing rate, as there was usually significant information content in the neuronal responses to phase differences that elicited the minimum firing rate. In general, burst responses (impulse intervals <4 ms) did not convey more information than that conveyed by the total response. The contribution to the cumulative information of the response in successive 100-ms segments decreased over the course of the 1-s stimulus. The ratio of information transmitted at 200 ms to that transmitted over the full second had a median of 0.30 while the ratio of 500 ms to 1 s was 0.68.
Publisher: Springer Science and Business Media LLC
Date: 13-08-2015
Publisher: Springer Berlin Heidelberg
Date: 2014
Publisher: Wiley
Date: 06-1997
DOI: 10.1111/J.1469-7793.1997.405BN.X
Abstract: 1. The spatial and temporal response properties of single cells in area 21a of the anaesthetized cat were assessed using drifting sinusoidal gratings presented at the optimum orientation for each cell. 2. Responses to sinusoidal gratings were dominated by an elevation of the mean discharge, with a relatively small modulated component at the temporal frequency of grating drift. The relative modulation ratio for the majority of cells was less than 1, similar to complex cells in the striate cortex. 3. Of those cells responsive to stimulation with sinusoidal gratings, 94% displayed spatial bandpass characteristics. Values derived from spatial frequency tuning curves were: mean optimum spatial frequency, 0.26 cycles deg-1 mean spatial resolution, 0.86 cycles deg-1 mean spatial bandwidth, 1.8 octaves and mean normalized bandwidth, 1.3. Two cells (6%) displayed spatial low-pass characteristics. 4. Approximately half our s le of cells (44%) displayed temporal low-pass tuning, while 35% displayed temporal bandpass characteristics. The mean optimum temporal frequency of bandpass cells was 3.3 Hz and the mean temporal bandwidth 1.9 octaves. The remaining cells were classified as temporal broadband (17%) and temporal high-pass (4%). 5. We conclude that the dominant functional input to cells with relatively high spatial frequency selectivity and/or temporal low-pass response properties most probably arises from area 17. The responses of the remaining cells may be explained by input from area 17 or 18.
Publisher: American Physiological Society
Date: 02-2021
Abstract: We present evidence for a generalized frequency processing strategy on tactile afferent inputs that is shared across a broad range of frequencies extending beyond the flutter range, supporting the notion that spike timing has an important role in shaping tactile perception.
Publisher: Wiley
Date: 1997
DOI: 10.1002/(SICI)1098-2396(199701)25:1<103::AID-SYN12>3.0.CO;2-0
Abstract: It is widely considered that sport and physical activities contribute to the development of human wellbeing. It is a fact that sport brings positive energy, discipline, and human wellbeing. Sports have an enormous effect on human health. Therefore, we assess the effects of the sports industry on the human health of China by using the autoregressive distributed lag (ARDL) approach from 1998 to 2020. Findings show that sports activities significantly improve human health and wellbeing. Tourism has found a positive influence on health and helped to contribute to human wellbeing. Empirical results prove that health expenditure and financial development significantly increase the population health in China. China's government should focus on the sports and tourism industry to play an important role in human health and wellbeing.
Publisher: Elsevier BV
Date: 1996
Publisher: Elsevier BV
Date: 04-2004
Publisher: American Physiological Society
Date: 10-2022
Abstract: The perceived intensity of a vibrotactile stimulus is thought to depend on single-neuron firing rates (rate coding) and the number of active afferents (population coding). Unaddressed until now is whether the temporal relation of in idual spikes also conveys information about tactile intensity. We used cutaneous electro-tactile stimulation to investigate how the temporal structure of a fixed number of spikes in a 1-s train influenced the perception of intensity. Four mean spike rates spanning the flutter and vibratory hum range (36 Hz, 60 Hz 120 Hz, 180 Hz) were tested, with spikes grouped into a regular pattern, or bursts of 2-6 spikes spaced 3 ms apart. To link a putative neural code to perception, perceived intensity was assessed in 16 human participants (aged 20-45 4 females) using the psychophysical paradigm of magnitude estimation. Compound sensory nerve action potentials were recorded to assess any stimulus variation in afferent recruitment. The temporal structuring of a fixed number of spikes into periodic bursts of multiple spikes altered perceived intensity as a function of burst spike count. The largest increase was seen at 36 Hz, where the bursts of six spikes were rated 2.1 times stronger than the regularly spaced spikes [95% confidence interval (CI): 1.9-2.3]. The true increase is likely larger as temporal structuring of spikes into bursts had some negative effect on afferent recruitment. We conclude that the perceived intensity can be modulated by changing temporal features of afferent discharge even when normalized for the number of recruited afferents. NEW & NOTEWORTHY Structuring a fixed number of spikes into temporal burst patterns evoke gradations of perceived intensity with burst spike count, emphasizing the importance of spike timing in primary afferents for shaping perception. This forms the basis for new strategies in communicating a range of intensity information to users of neural interfaces by simply varying the timing of spikes in nonspecific primary afferents using fixed-charge electric pulses, without requiring alterations in stimulation current or mean pulse frequency.
Publisher: Cold Spring Harbor Laboratory
Date: 10-04-2020
DOI: 10.1101/2020.04.10.033241
Abstract: We have previously described a novel temporal encoding mechanism in the somatosensory system, where mechanical pulses grouped into periodic bursts create a perceived tactile frequency based on the duration of the silent gap between bursts, rather than the mean rate or the periodicity. This coding strategy may offer new opportunities for transmitting information to the brain using various sensory neural prostheses and haptic interfaces. However, it was not known whether the same coding mechanisms apply when using electrical stimulation, which recruits a different spectrum of afferents. Here, we demonstrate that the predictions of the burst gap coding model for frequency perception apply to burst stimuli delivered with electrical pulses, re-emphasising the importance of the temporal structure of spike patterns in neural processing and perception of tactile stimuli. Reciprocally, the electrical stimulation data confirm that the results observed with mechanical stimulation do indeed depend on neural processing mechanisms in the central nervous system, and are not due to skin mechanical factors and resulting patterns of afferent activation.
Publisher: Wiley
Date: 1999
DOI: 10.1111/J.1469-7793.1999.541AE.X
Abstract: 1. Binocular interactions related to retinal disparity were investigated in single neurons in area 21a of extrastriate cortex in the anaesthetized cat using sinusoidal luminance gratings. 2. The responses of approximately two-thirds of neurons were profoundly modulated by a relative phase difference between identical drifting gratings presented to each eye. This modulation included both facilitatory and inhibitory interocular interactions. The selectivity for binocular disparity was about twice as sharp as the selectivity for monocular spatial position. 3. Significant phase modulation was retained in many neurons at interocular orientation differences exceeding 45 deg. The response suppression associated with stimulation at a phase shift 180 deg from the optimum was stronger than the response suppression to an interocular orientation difference of 90 deg. 4. The proportion of phase modulated neurons and the potency of modulation in area 21a neurons exceed that reported for phase-selective complex cells in area 17. Neurons in area 21a show sharp disparity tuning that is relatively insensitive to changes in orientation and monocular position, which suggests that this extrastriate region has a role in stereoscopic depth perception.
Publisher: Springer Science and Business Media LLC
Date: 07-1995
DOI: 10.1007/BF00242183
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 09-1997
DOI: 10.1097/00001756-199709290-00033
Abstract: We investigated binocular interactions in area 21a cells of the anaesthetized cat. Visual stimuli were drifting sinusoidal gratings presented at the same optimal orientation in each eye (iso-oriented condition) or at the optimal orientation in the dominant eye and the orthogonal orientation in the other eye (orthogonal condition). In 68% of cells the response in the binocular iso-oriented condition was greater than the dominant eye monocular response, while in 88% of cells the response in the binocular orthogonal condition was less than the dominant eye monocular response. Our results suggest a possible role for this extrastriate region of cortex in binocular contour rivalry.
Publisher: Society for Neuroscience
Date: 04-05-2023
DOI: 10.1523/JNEUROSCI.1305-22.2023
Abstract: Dexterous object manipulation depends critically on information about forces normal and tangential to the fingerpads, and also on torque associated with object orientation at grip surfaces. We investigated how torque information is encoded by human tactile afferents in the fingerpads and compared them to 97 afferents recorded in monkeys ( n = 3 2 females) in our previous study. Human data included slowly-adapting Type-II (SA-II) afferents, which are absent in the glabrous skin of monkeys. Torques of different magnitudes (3.5–7.5 mNm) were applied in clockwise and anticlockwise directions to a standard central site on the fingerpads of 34 human subjects (19 females). Torques were superimposed on a 2, 3, or 4 N background normal force. Unitary recordings were made from fast-adapting Type-I (FA-I, n = 39), and slowly-adapting Type-I (SA-I, n = 31) and Type-II (SA-II, n = 13) afferents supplying the fingerpads via microelectrodes inserted into the median nerve. All three afferent types encoded torque magnitude and direction, with torque sensitivity being higher with smaller normal forces. SA-I afferent responses to static torque were inferior to dynamic stimuli in humans, while in monkeys the opposite was true. In humans this might be compensated by the addition of sustained SA-II afferent input, and their capacity to increase or decrease firing rates with direction of rotation. We conclude that the discrimination capacity of in idual afferents of each type was inferior in humans than monkeys which could be because of differences in fingertip tissue compliance and skin friction. SIGNIFICANCE STATEMENT We investigated how in idual human tactile nerve fibers encode rotational forces (torques) and compared them to their monkey counterparts. Human hands, but not monkey hands, are innervated by a tactile neuron type (SA-II afferents) specialized to encode directional skin strain yet, so far, torque encoding has only been studied in monkeys. We find that human SA-I afferents were generally less sensitive and less able to discriminate torque magnitude and direction than their monkey counterparts, especially during the static phase of torque loading. However, this shortfall in humans could be compensated by SA-II afferent input. This indicates that variation in afferent types might complement each other signaling different stimulus features possibly providing computational advantage to discriminate stimuli.
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 08-1999
DOI: 10.1097/00001756-199908020-00003
Abstract: We investigated binocular suppression in area 21a cells of the anaesthetized cat using drifting sinusoidal gratings presented simultaneously to each eye. The grating presented to the dominant eye was always oriented optimally and the grating presented to the non-dominant eye was either at the same orientation, but at the least effective relative spatial phase, or orthogonal. The binocular response of approximately 80% of cells was less than the monocular dominant eye response when there was a mismatch in orientation or spatial location between stimuli. Response suppression in the two binocular stimulus conditions had a correlation coefficient (r) of 0.55. We propose a parsimonious model to account for the response facilitation and suppression by binocular stimulation of area 21a neurons.
Publisher: Springer International Publishing
Date: 2016
Publisher: Cambridge University Press (CUP)
Date: 06-2007
DOI: 10.1111/J.1601-5215.2007.00206.X
Abstract: To present the argument that the only secure foundation for a theory of behaviour, and ultimately of mind, rests at the level of single neurons, and to assess progress at this level of explanation. Relevant data were obtained by a search of PubMed, last updated in January 2007, focused on implemented models from single-neuron studies. Technical limitations on recording neural activity produce trade-offs between temporal and spatial resolution and the ability to track the massively parallel activity of the nervous system. The properties of the single neuron that would need to be measured and the techniques available to obtain the data are described. The concept of a fixed neuronal identity may be impeding progress and should be replaced with the concept of dynamically assigned neuron identity. Modern data collection techniques make it possible to obtain data at the single-neuron level on the complete nervous systems of simple organisms. Present models based on this data do not provide an integrated explanation of behaviour. However, there do not appear to be insurmountable theoretical or practical obstacles to building such models in the future or of scaling the data collection up to more complex organisms.
Publisher: Wiley
Date: 26-06-2021
DOI: 10.1002/CNE.24942
Abstract: The dorsal column nuclei complex (DCN-complex) includes the dorsal column nuclei (DCN, referring to the gracile and cuneate nuclei collectively), external cuneate, X, and Z nuclei, and the median accessory nucleus. The DCN are organized by both somatotopy and modality, and have a erse range of afferent inputs and projection targets. The functional organization and connectivity of the DCN implicate them in a variety of sensorimotor functions, beyond their commonly accepted role in processing and transmitting somatosensory information to the thalamus, yet this is largely underappreciated in the literature. To consolidate insights into their sensorimotor functions, this review examines the morphology, organization, and connectivity of the DCN and their associated nuclei. First, we briefly discuss the receptors, afferent fibers, and pathways involved in conveying tactile and proprioceptive information to the DCN. Next, we review the modality and somatotopic arrangements of the remaining constituents of the DCN-complex. Finally, we examine and discuss the functional implications of the myriad of DCN-complex projection targets throughout the diencephalon, midbrain, and hindbrain, in addition to their modulatory inputs from the cortex. The organization and connectivity of the DCN-complex suggest that these nuclei should be considered a complex integration and distribution hub for sensorimotor information.
Publisher: Wiley
Date: 07-1992
DOI: 10.1113/JPHYSIOL.1992.SP019247
Abstract: 1. Recordings were made from single slowly adapting type I (SAI) afferent fibres associated with touch domes in the cat hairy skin. Controlled vibratory stimuli were used first, to characterize the precision with which these SAI afferents reflect the temporal aspects of vibrotactile stimuli, and second, to determine whether earlier disparate reports of SAI responsiveness to vibration may be attributable to highly specific stimulus requirements. 2. Eighteen SAI fibres from femoral cutaneous nerve branches were examined each was associated with one to three touch domes. SAI responses to both steps and sinusoidal vibration (1-1.5 s in duration) were affected profoundly by both probe size and position. Punctate stimulus probes (250 microns) produced much higher response levels and steeper stimulus-response relations than those elicited with large (2 mm) probes, probably on account of focal distortion created within the dome by the smaller probes. SAI sensitivity to vibration was also affected markedly by the litude of any pre-indentation on which the vibration was superimposed sensitivity was much lower when the pre-indentation exceeded 100 microns, in particular with larger stimulus probes. 3. Measures of both vibration sensitivity and the precision of impulse patterning demonstrated that, if appropriate stimulus parameters are chosen, the SAI fibres can respond to 1 s trains of vibration ( litude < or = 100 microns) in a tightly phase-locked, 1:1 manner for frequencies up to 500 Hz. At frequencies from approximately 100-500 Hz the SAI fibres displayed broad 1:1 plateaus, where their response rate remained constant over a range of litudes, and phased-locking was tightest. Responses remained phase-locked up to 1000 Hz, but could not follow the vibration with a 1:1 pattern above 500 Hz. 4. The results demonstrate that with appropriate stimulus parameters, touch dome-associated SAI fibres are capable of signalling vibrotactile information over a similar bandwidth of frequencies as do Pacinian sensory fibres. The variability in past reports of SAI vibration sensitivity may relate principally to differences in stimulus conditions. However, in view of the SAI capacity for responding to vibration with temporally precise, patterned activity, it appears that their reported failure to contribute to vibrotactile sensibility must be attributed to limitations imposed in the central processing of SAI signals.
Publisher: Institute of Electrical and Electronics Engineers (IEEE)
Date: 2022
Publisher: Common Ground Research Networks
Date: 2018
Publisher: Wiley
Date: 08-2007
DOI: 10.1111/J.1460-9568.2007.05729.X
Abstract: A number of human and animal studies have reported a differential representation of the frequency of vibrotactile stimuli in the somatosensory cortices: neurons in the primary somatosensory cortex (SI) are predominantly responsive to lower frequencies of tactile vibration, and those in the secondary somatosensory cortex (SII) are predominantly responsive to higher frequencies. We employed transcranial magnetic stimulation (TMS) over SI in human subjects to investigate the extent to which the inactivation of SI disrupted the discrimination of vibrotactile stimulation at frequencies that give rise to the tactile sensations of flutter (30 Hz) and vibration (200 Hz). Frequency discrimination around the 30-Hz standard following application of TMS to SI was reduced in seven of the eight subjects, and around the 200-Hz standard was reduced in all eight subjects. The average change in discrimination following TMS was about 20% for both low and high frequencies of vibrotactile stimulation. These data suggest that disruption of SI: (1) has a direct effect on the discrimination of both low and high frequencies of vibrotactile stimuli, consistent with a serial model of processing, or (2) has a direct effect on low-frequency vibrotactile stimuli and an indirect effect on the processing of high-frequency vibrotactile stimuli by SII via cortico-cortical connections between the two regions.
Publisher: IEEE
Date: 07-2013
Publisher: Elsevier BV
Date: 05-2017
DOI: 10.1016/J.CUB.2017.04.011
Abstract: Skin vibrations sensed by tactile receptors contribute significantly to the perception of object properties during tactile exploration [1-4] and to sensorimotor control during object manipulation [5]. Sustained low-frequency skin vibration (<60 Hz) evokes a distinct tactile sensation referred to as flutter whose frequency can be clearly perceived [6]. How afferent spiking activity translates into the perception of frequency is still unknown. Measures based on mean spike rates of neurons in the primary somatosensory cortex are sufficient to explain performance in some frequency discrimination tasks [7-11] however, there is emerging evidence that stimuli can be distinguished based also on temporal features of neural activity [12, 13]. Our study's advance is to demonstrate that temporal features are fundamental for vibrotactile frequency perception. Pulsatile mechanical stimuli were used to elicit specified temporal spike train patterns in tactile afferents, and subsequently psychophysical methods were employed to characterize human frequency perception. Remarkably, the most salient temporal feature determining vibrotactile frequency was not the underlying periodicity but, rather, the duration of the silent gap between successive bursts of neural activity. This burst gap code for frequency represents a previously unknown form of neural coding in the tactile sensory system, which parallels auditory pitch perception mechanisms based on purely temporal information where longer inter-pulse intervals receive higher perceptual weights than short intervals [14]. Our study also demonstrates that human perception of stimuli can be determined exclusively by temporal features of spike trains independent of the mean spike rate and without contribution from population response factors.
Publisher: Elsevier BV
Date: 1996
Publisher: Springer Singapore
Date: 15-09-2016
Publisher: Wiley
Date: 1996
DOI: 10.1002/(SICI)1098-1063(1996)6:1<3::AID-HIPO2>3.0.CO;2-S
Publisher: Cambridge University Press (CUP)
Date: 10-1999
DOI: 10.1017/S0140525X99492192
Abstract: The complexity of modern neurobiology in even a comparatively restricted area such as use-dependent synaptic plasticity is underestimated by the authors. This leads them to reject a neurobiological model of learning as conceptually parasitic on the psychology of conditioning, on the basis of objections that are shown to be unsustainable. An argument is also advanced that neurobiologists hold an intermediate version of the neuron doctrine rather than a conflated one. In this version, neurobiologists believe that psychology will eventually be underpinned by neurobiology but are agnostic about the extent of upheaval that this will produce in psychology.
Publisher: Public Library of Science (PLoS)
Date: 12-09-2014
Publisher: American Physiological Society
Date: 12-1997
DOI: 10.1152/JN.1997.78.6.3039
Abstract: Vickery, R. M., Shanida H. Morris, and Lynn J. Bindman. Metabotropic glutamate receptors are involved in long-term potentiation in isolated slices of rat medial frontal cortex. J. Neurophysiol. 78: 3039–3046, 1997. The prelimbic region of medial frontal cortex in the rat receives a direct input from the hippoc us and this functional connection is essential for aspects of spatial memory. Activity-dependent changes in the effectiveness of synaptic transmission in the medial frontal cortex, namely long-term potentiation (LTP) and long-term depression (LTD) can persist for tens of minutes or hours and may be the basis of learning and memory storage. Glutamatergic activation of ionotropic receptors is required to induce both LTP and LTD. We now present evidence of the involvement of metabotropic glutamate receptors in LTP in isolated slices of frontal cortex. Repetitive bursts of stimulation at theta frequencies (TBS) were applied to layer II, and monosynaptic EPSPs were monitored in layer V neurons of the prelimbic area. TBS was found to be more effective at inducing LTP than tetanic stimulation at 100 Hz and produced LTP that lasted min in 8 out of 14 neurons. Tetanic stimulation at 100 Hz in the presence of the N-methyl-d-aspartate (NMDA)-antagonist 2-amino-5-phosphonopentanoate (AP5) was reported to be a reliable method of inducing LTD in prelimbic cortex ( Hirsch and Crépel 1991 ). However we found that this protocol did not facilitate the induction of LTD. The role of metabotropic glutamate receptors (mGluR) in LTP was assessed by using the selective, broad-spectrum antagonist (R, S)-α-methyl-4- carboxyphenylglycine (MCPG). This drug significantly reduced the incidence of LTP after TBS to only 1 of 14 neurons ( P 0.02, χ 2 test). The pooled responses to TBS in MCPG showed significantly reduced potentiation [( P 0.02, analysis of variance (ANOVA)]. The broad-spectrum mGluR agonist (1S,3R)-1-aminocyclopentane-1,3-dicarboxylic acid (ACPD) and the selective group I agonist S-3 hydroxyphenylglycine(S-3HPG) both produced membrane depolarization, an increase in number of spikes evoked by depolarizing current pulses, and a reduction in the afterhyperpolarization. Similar effects were produced by these agonists even when synaptic transmission was blocked by use of the γ-aminobutyric acid-B (GABA B ) receptor agonist, 200 μM baclofen, which suggests that group I mGluRs are present on layer V neurons. We conclude that mGluRs participate in the production of LTP in prelimbic cortex, and that this excitatory effect could be mediated by the postsynaptic group I mGluRs.
Start Date: 03-2020
End Date: 12-2024
Amount: $550,000.00
Funder: Australian Research Council
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