A phenomenological model of visually evoked spike trains in cat geniculate nonlagged X-cells

1998 ◽  
Vol 15 (6) ◽  
pp. 1157-1174 ◽  
Author(s):  
NICOLAS GAZÈRES ◽  
LYLE J. BORG-GRAHAM ◽  
YVES FRÉGNAC
Keyword(s):  
Visual Information ◽  
Cell Model ◽  
Receptive Fields ◽  
Spike Trains ◽  
Mathematical Framework ◽  
Visual Response ◽  
Visual Responses ◽  
Cortical Cells ◽  
Cortical Receptive Fields ◽  
X Cells

The visual information that first-order cortical cells receive is contained in the visually evoked spike trains of geniculate relay cells. To address functional issues such as the ON/OFF structure of visual cortical receptive fields with modelling studies, a geniculate cell model is needed where the spatial and temporal characteristics of the visual response are described quantitatively. We propose a model simulating the spike trains produced by cat geniculate nonlagged X-cells, based on a review of the electrophysiological literature. The level of description chosen is phenomenological, fitting the dynamics and amplitude of phasic and tonic responses, center/surround antagonism, surround excitatory responses, and the statistical properties of both spontaneous and visually evoked spike trains. The model, which has been constrained so as to reproduce the responses to centered light spots of expanding size and optimal light and dark annuli, predicts responses to thin and large bars flashed in various positions of the receptive field. The switching gamma renewal process method has been introduced for modelling spontaneous and visually evoked spike trains within the same mathematical framework. The statistical structure of the spike process is assumed to be more regular during phasic than tonic visual responses. On the whole, this model generates more realistic geniculate input to cortex than the currently used retinal models.

Responses of cells in the tail of the caudate nucleus during visual discrimination learning

1995 ◽  
Vol 74 (3) ◽  
pp. 1083-1094 ◽  
Author(s):  
V. J. Brown ◽  
R. Desimone ◽  
M. Mishkin
Keyword(s):  
Caudate Nucleus ◽  
Visual Discrimination ◽  
Visual Information ◽  
Visual Learning ◽  
Visual Fields ◽  
Receptive Fields ◽  
Visual Responses ◽  
Neuronal Responses ◽  
Association Learning ◽  
Visual Properties

1. The tail of the caudate nucleus and adjacent ventral putamen (ventrocaudal neostriatum) are major projection sites of the extrastriate visual cortex. Visual information is then relayed, directly or indirectly, to a variety of structures with motor functions. To test for a role of the ventrocaudal neostriatum in stimulus-response association learning, or habit formation, neuronal responses were recorded while monkeys performed a visual discrimination task. Additional data were collected from cells in cortical area TF, which serve as a comparison and control for the caudate data. 2. Two monkeys were trained to perform an asymmetrically reinforced go-no go visual discrimination. The stimuli were complex colored patterns, randomly assigned to be either positive or negative. The monkey was rewarded with juice for releasing a bar when a positive stimulus was presented, whereas a negative stimulus signaled that no reward was available and that the monkey should withhold its response. Neuronal responses were recorded both while the monkey performed the task with previously learned stimuli and while it learned the task with new stimuli. In some cases, responses were recorded during reversal learning. 3. There was no evidence that cells in the ventrocaudal neostriatum were influenced by the reward contingencies of the task. Cells did not fire preferentially to the onset of either positive or negative stimuli; neither did cells fire in response to the reward itself or in association with the motor response of the monkey. Only visual responses were apparent. 4. The visual properties of cells in these structures resembled those of cells in some of the cortical areas projecting to them. Most cells responded selectively to different visual stimuli. The degree of stimulus selectivity was assessed with discriminant analysis and was found to be quantitatively similar to that of inferior temporal cells tested with similar stimuli. Likewise, like inferior temporal cells, many cells in the ventrocaudal neostriatum had large, bilateral receptive fields. Some cells had "doughnut"-shaped receptive fields, with stronger responses in the periphery of both visual fields than at the fovea, similar to the fields of some cells in the superior temporal polysensory area. Although the absence of task-specific responses argues that ventrocaudal neostriatal cells are not themselves the mediators of visual learning in the task employed, their cortical-like visual properties suggest that they might relay visual information important for visuomotor plasticity in other structures. (ABSTRACT TRUNCATED AT 400 WORDS)

Lateral geniculate neurons in behaving primates. I. Responses to two-dimensional stimuli

1991 ◽  
Vol 66 (3) ◽  
pp. 777-793 ◽  
Author(s):  
J. W. McClurkin ◽  
T. J. Gawne ◽  
B. J. Richmond ◽  
L. M. Optican ◽  
D. L. Robinson
Keyword(s):  
Receptive Field ◽  
Visual Information ◽  
Receptive Fields ◽  
Nonlinear Behavior ◽  
Temporal Patterns ◽  
Two Dimensional ◽  
Visual Responses ◽  
Linear Summation ◽  
Lateral Geniculate ◽  
Opposite Contrast

1. Using behaving monkeys, we studied the visual responses of single neurons in the parvocellular layers of the lateral geniculate nucleus (LGN) to a set of two-dimensional black and white patterns. We found that monkeys could be trained to make sufficiently reliable and stable fixations to enable us to plot and characterize the receptive fields of individual neurons. A qualitative examination of rasters and a statistical analysis of the data revealed that the responses of neurons were related to the stimuli. 2. The data from 5 of the 13 "X-like" neurons in our sample indicated the presence of antagonistic center and surround mechanisms and linear summation of luminance within center and surround mechanisms. We attribute the lack of evidence for surround antagonism in the eight neurons that failed to exhibit center-surround antagonism either to a mismatch between the size of the pixels in the stimuli and the size of the receptive field or to the lack of a surround mechanism (i.e., the type II neurons of Wiesel and Hubel). 3. The data from five other neurons confirm and extend previous reports indicating that the surround regions of X-like neurons can have nonlinearities. The responses of these neurons were not modulated when a contrast-reversing, bipartite stimulus was centered on the receptive field, which suggests a linear summation within the center and surround mechanisms. However, it was frequently the case for these neurons that stimuli of identical pattern but opposite contrast elicited responses of similar polarity, which indicates nonlinear behavior. 4. We found a wide variety of temporal patterns in the responses of individual LGN neurons, which included differences in the magnitude, width, and number of peaks of the initial on-transient and in the magnitude of the later sustained component. These different temporal patterns were repeatable and clearly different for different visual patterns. These results suggest that visual information may be carried in the shape as well as in the amplitude of the response waveform.

Time Course of Attentional Modulation in the Frontal Eye Field During Curve Tracing

2009 ◽  
Vol 101 (4) ◽  
pp. 1813-1822 ◽  
Author(s):  
P. S. Khayat ◽  
A. Pooresmaeili ◽  
P. R. Roelfsema
Keyword(s):  
Visual Information ◽  
Time Course ◽  
Stimulus Presentation ◽  
Frontal Eye Field ◽  
Stimulus Selection ◽  
Visual Response ◽  
Visual Responses ◽  
Cortical Regions ◽  
Visual Cortical ◽  
Curve Tracing

Neurons in the frontal eye fields (FEFs) register incoming visual information and select visual stimuli that are relevant for behavior. Here we investigated the timing of the visual response and the timing of selection by recording from single FEF neurons in a curve-tracing task that requires shifts of attention followed by an oculomotor response. We found that the behavioral selection signal in area FEF had a latency of 147 ms and that it was delayed substantially relative to the visual response, which occurred 50 ms after stimulus presentation. We compared the FEF responses to activity previously recorded in the primary visual cortex (area V1) during the same task. Visual responses in area V1 preceded the FEF responses, but the latencies of selection signals in areas V1 and FEF were similar. The similarity of timing of selection signals in structures at opposite ends of the visual cortical processing hierarchy supports the view that stimulus selection occurs in an interaction between widely separated cortical regions.

Visual motion response properties of neurons in dorsolateral pontine nucleus of alert monkey

1990 ◽  
Vol 63 (1) ◽  
pp. 37-59 ◽  
Author(s):  
D. A. Suzuki ◽  
J. G. May ◽  
E. L. Keller ◽  
R. D. Yee
Keyword(s):  
Retinal Image ◽  
Visual Motion ◽  
Receptive Fields ◽  
Response Amplitude ◽  
Large Field ◽  
Visual Response ◽  
Visual Responses ◽  
Pontine Nucleus ◽  
Motion Responses ◽  
Dorsolateral Pontine Nucleus

1. In this study we sought to characterize the visual motion processing that exists in the dorsolateral pontine nucleus (DLPN) and make a comparison with the reported visual responses of the middle temporal (MT) and medial superior temporal (MST) areas of the monkey cerebral cortex. The DLPN is implicated as a component of the visuomotor interface involved with the regulation of smooth-pursuit eye movements, because it is a major terminus for afferents from MT and MST and also the source of efferents to cerebellar regions involved with eye-movement control. 2. Some DLPN cells were preferentially responsive to discrete (spot and bar) visual stimuli, or to large-field, random-dot pattern motion, or to both discrete and large-field visual motion. The results suggest differential input from localized regions of MT and MST. 3. The visual-motion responses of DLPN neurons were direction selective for 86% of the discrete visual responses and 95% of the large-field responses. Direction tuning bandwidths (full-width at 50% maximum response amplitude) averaged 107 degrees and 120 degrees for discrete and large-field visual motion responses, respectively. For the two visual response types, the direction index averaged 0.95 and 1.02, indicating that responses to stimuli moving in preferred directions were, on average, 20 and 50 times greater than responses to discrete or large-field stimulus movement in the opposite directions, respectively. 4. Most of the DLPN visual responses to movements of discrete visual stimuli exhibited increases in amplitude up to preferred retinal image speeds between 20 and 80 degrees/s, with an average preferred speed of 39 degrees/s. At higher speeds, the response amplitude of most units decreased, although a few units exhibited a broad saturation in response amplitude that was maintained up to at least 150 degrees/s before the response decreased. Over the range of speeds up to the preferred speeds, the sensitivity of DLPN neurons to discrete stimulus-related, retinal-image speed averaged 3.0 spikes/s per deg/s. The responses to large-field visual motion were less sensitive to retinal image speed and exhibited an average sensitivity of 1.4 spikes/s per deg/s before the visual response saturated. 5. DLPN and MT were quantitatively comparable with respect to degree of direction selectivity, retinal image speed tuning, and distribution of preferred speeds. Many DLPN receptive fields contained the fovea and were larger than those of MT and more like MST receptive fields in size.(ABSTRACT TRUNCATED AT 400 WORDS)

Limiting Factors for the Detection of Orientation

Perception ◽  
1998 ◽  
Vol 27 (2) ◽  
pp. 167-181
Author(s):  
Johannes M Zanker
Keyword(s):  
Visual Field ◽  
Visual Information ◽  
Receptive Fields ◽  
Limiting Factors ◽  
Visual Stream ◽  
Local Operation ◽  
Cortical Magnification ◽  
Orientation Detection ◽  
Cortical Magnification Factor ◽  
Cortical Receptive Fields

First steps of visual-information processing in primates are characterised by a highly ordered representation of the outside world on the cortex. Two prominent features of cortical organisation are the retinotopic mapping of position in the visual field on the first stages of the visual stream, and the systematic variation of orientation preference in the same areas. In an attempt to understand the relation of position and orientation representation, we need to know the minimum spatial requirements for orientation detection. In the present paper, the spatial limits for detecting orientation are analysed by simulating simple orientation filters and testing the ability of human observers to detect the orientation of small lines at various positions in the visual field. At sufficiently high contrast levels, the minimum physical length of a line to discriminate orientation differences of 45°–90° is not constant when presented at various eccentricities, but covaries inversely with the cortical magnification factor. In consequence, a line needs to correspond to about 0.2 mm of cortical surface, independently of the actual eccentricity at which the stimulus is presented, in order to allow observers to recognise its orientation. This has consequences for our understanding of orientation detection, (i) In combination with simulation experiments, it becomes clear that the elementary process underlying orientation detection is a local operation, which seems to focus on small regions compared with cortical receptive fields, (ii) With respect to the number of inputs to the visual cortex, the performance of this local operation approaches the physical limits, requiring hardly more than three-four input LGN axons to be activated for detecting the orientation of a highly visible line segment. Comparing these spatial characteristics with the receptive fields of orientation-sensitive neurons in the primate visual system could suggest new insights into the neuronal circuits underlying orientation mapping in the human cortex.

Functional properties of monkey caudate neurons. II. Visual and auditory responses

1989 ◽  
Vol 61 (4) ◽  
pp. 799-813 ◽  
Author(s):  
O. Hikosaka ◽  
M. Sakamoto ◽  
S. Usui
Keyword(s):  
Target Location ◽  
Receptive Fields ◽  
The Other ◽  
Visual Response ◽  
Visual Responses ◽  
Auditory Responses ◽  
Small Spot ◽  
Motor Set ◽  
Sensory Responses ◽  
The One

1. Visual responses of caudate neurons were studied in monkeys trained to fixate on a small spot of light. A visual stimulus (another spot of light) was presented in various contexts of behavior using different behavioral paradigms. Visual receptive fields were usually large and centered on the contralateral hemifield. Among 217 neurons with visual responses, 184 were further classified into subtypes. 2. Visual responses in 64 neurons were not modulated by changing the paradigms (unconditional visual responses). In the other neurons, visual responses were dependent on the behavioral contexts in which the stimulus was presented. Three types of behavioral modulation were found. 3. A saccade-enhanced visual response (n = 37) was the one that was enhanced if the monkey made a saccade to the stimulus on its appearance. The enhancement was spatially selective: the response was depressed if the saccade was directed away from the stimulus. 4. Memory-contingent visual responses (n = 36) were present preferentially when the monkey remembered the location of the stimulus and a few seconds later made a saccade to the remembered location. Responses were greater when the location of the stimulus was randomized between trials. 5. Expectation-contingent visual responses (n = 46) were present preferentially when the stimulus came on while the monkey was not fixating another spot, and the stimulus was related directly to a reward. Unlike the other types, its receptive field included both contralateral and ipsilateral hemifields without a particular preference. 6. A small number of neurons (n = 16) showed a visual response that easily habituated. 7. Latencies of visual responses were usually between 100 and 200 ms. The latencies of the memory-contingent, expectation-contingent, and habituated visual responses tended to be longer than the others and tended to be more variable between trials. 8. Among auditory responsive neurons only a small proportion were related to the tasks. The response was greater to a contralateral sound. It was enhanced if the monkey used the sound as the cue for the future target location. 9. The results suggest that sensory responses of caudate neurons could be used to guide a subsequent sequence of learned behaviors by confirming predicted environmental states, renewing memory, or establishing a motor set.

scholarly journals Spatiotemporal characteristics of retinal response to network-mediated photovoltaic stimulation

2018 ◽  
Vol 119 (2) ◽  
pp. 389-400 ◽  
Author(s):  
Elton Ho ◽  
Richard Smith ◽  
Georges Goetz ◽  
Xin Lei ◽  
Ludwig Galambos ◽  
...  
Keyword(s):  
Retinal Ganglion Cells ◽  
Visual Information ◽  
Ganglion Cells ◽  
Ex Vivo ◽  
Receptive Fields ◽  
Low Frequency ◽  
Frame Rate ◽  
Field Size ◽  
Retinal Ganglion ◽  
Visual Responses

Subretinal prostheses aim at restoring sight to patients blinded by photoreceptor degeneration using electrical activation of the surviving inner retinal neurons. Today, such implants deliver visual information with low-frequency stimulation, resulting in discontinuous visual percepts. We measured retinal responses to complex visual stimuli delivered at video rate via a photovoltaic subretinal implant and by visible light. Using a multielectrode array to record from retinal ganglion cells (RGCs) in the healthy and degenerated rat retina ex vivo, we estimated their spatiotemporal properties from the spike-triggered average responses to photovoltaic binary white noise stimulus with 70-μm pixel size at 20-Hz frame rate. The average photovoltaic receptive field size was 194 ± 3 μm (mean ± SE), similar to that of visual responses (221 ± 4 μm), but response latency was significantly shorter with photovoltaic stimulation. Both visual and photovoltaic receptive fields had an opposing center-surround structure. In the healthy retina, ON RGCs had photovoltaic OFF responses, and vice versa. This reversal is consistent with depolarization of photoreceptors by electrical pulses, as opposed to their hyperpolarization under increasing light, although alternative mechanisms cannot be excluded. In degenerate retina, both ON and OFF photovoltaic responses were observed, but in the absence of visual responses, it is not clear what functional RGC types they correspond to. Degenerate retina maintained the antagonistic center-surround organization of receptive fields. These fast and spatially localized network-mediated ON and OFF responses to subretinal stimulation via photovoltaic pixels with local return electrodes raise confidence in the possibility of providing more functional prosthetic vision. NEW & NOTEWORTHY Retinal prostheses currently in clinical use have struggled to deliver visual information at naturalistic frequencies, resulting in discontinuous percepts. We demonstrate modulation of the retinal ganglion cells (RGC) activity using complex spatiotemporal stimuli delivered via subretinal photovoltaic implant at 20 Hz in healthy and in degenerate retina. RGCs exhibit fast and localized ON and OFF network-mediated responses, with antagonistic center-surround organization of their receptive fields.

Effect of stimulus contrast and size on NMDA receptor activity in cat lateral geniculate nucleus

1992 ◽  
Vol 68 (1) ◽  
pp. 182-196 ◽  
Author(s):  
Y. H. Kwon ◽  
S. B. Nelson ◽  
L. J. Toth ◽  
M. Sur
Keyword(s):  
Nmda Receptor ◽  
Stimulus Size ◽  
Optimal Size ◽  
Visual Response ◽  
Visual Responses ◽  
Stimulus Contrast ◽  
Surround Inhibition ◽  
X Cells ◽  
Contrast Response ◽  
Receptive Field Center

1. We studied the effect of varying excitatory and inhibitory drive on the N-methyl-D-aspartate (NMDA) receptor-mediated component of the visual responses of neurons in the cat dorsal lateral geniculate nucleus (dLGN) by varying the contrast and size of stimuli presented to the receptive fields of these cells. 2. Cells were classified as either on- or off-center, X or Y, and lagged or nonlagged. Stimulus contrast, and hence the amount of excitatory drive, was varied by changing the brightness of a spot, whose size and location matched the cell's receptive field center, relative to a fixed background luminance. Responses to varying contrast were collected from each cell before, during, and after iontophoretic application of D-2-amino-5-phosphonovaleric acid (D-APV), a specific NMDA receptor antagonist. From each contrast-response plot, a sigmoidal curve fit yielded five parameters on which we examined the effect of D-APV: the threshold contrast, saturation contrast, contrast at half saturation (C50), slope (gain) at C50, and saturation response. 3. In most cells, application of D-APV reduced both the saturation response and the gain of the contrast-response curve, but did not reduce or change significantly the threshold contrast, saturation contrast, or C50. 4. Cells varied in their sensitivity to D-APV, but for any given cell, the D-APV-sensitive component was nearly always a linear function of the control visual response level. Thus, for a spot of optimal size, there was a constant proportion of the visual response attributable to NMDA receptors, regardless of the amplitude of the response. 5. When the effect of D-APV on the visual responses to an optimal spot at varying contrasts was compared among different classes of dLGN cells, the visual responses of lagged X cells were reduced to a greater extent than those of either nonlagged X cells or the combined population of nonlagged X and Y cells. 6. Stimulus size (spot diameter) was also varied systematically at a fixed contrast to vary the inhibitory drive to dLGN cells. As stimulus size was increased, the response first increased because of increased stimulation of the receptive field center and then decreased because of increasing amounts of surround inhibition. 7. The D-APV-sensitive component of individual cell responses was greater when the stimulus spot was less than or equal to optimal size than when the spot was larger. Thus the contribution of NMDA receptors to the visual response decreased with increasing surround inhibition.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals No on-off Maps in Supragranular Layers of Ferret Visual Cortex

2002 ◽  
Vol 88 (4) ◽  
pp. 2163-2166 ◽  
Author(s):  
Barbara Chapman ◽  
Imke Gödecke
Keyword(s):  
Visual Cortex ◽  
Ocular Dominance ◽  
Receptive Fields ◽  
Visual Space ◽  
Cortical Layer ◽  
Cortical Function ◽  
Cortical Cells ◽  
Cortical Inputs ◽  
Cortical Receptive Fields ◽  
Visual Cortical

Primary visual cortex contains functional maps of a number of stimulus properties including ocular dominance, orientation, direction, color, and spatial frequency. These maps must be organized with respect to each other and to a single continuous retinotopic map of visual space such that each stimulus parameter is represented at each point in space. In the ferret, geniculo-cortical inputs to cortical layer IV are segregated into on- andoff-center patches, suggesting the possibility that there might be an additional cortical map in this species. We have used optical imaging of intrinsic signals to search for on-offmaps in ferret visual cortical cells and have found none. This suggests that the high degree of on-off segregation seen subcortically in the ferret may play a role in the development of visual cortical receptive fields rather than in adult cortical function.

Pulvinar nuclei of the behaving rhesus monkey: visual responses and their modulation

1985 ◽  
Vol 54 (4) ◽  
pp. 867-886 ◽  
Author(s):  
S. E. Petersen ◽  
D. L. Robinson ◽  
W. Keys
Keyword(s):  
Discharge Rate ◽  
Receptive Fields ◽  
Stimulus Onset ◽  
Visual Response ◽  
Visual Responses ◽  
Response Latencies ◽  
Stimulus Movement ◽  
Selective Visual Attention ◽  
Retinotopic Organization ◽  
A Cell

We have examined the properties of neurons in three subdivisions of the pulvinar of alert, trained rhesus monkeys 1) an inferior, retinotopically mapped area (PI), 2) a lateral, retinotopically organized region (PL), and 3) a dorsomedial visual portion of the lateral pulvinar (Pdm), which has a crude retinotopic organization. We tested the neurons for visual responses to stationary and moving stimuli and for changes in these responses produced by behavioral manipulations. All areas contain cells sensitive to stimulus orientation as well as neurons selective for the direction of stimulus movement; however, the majority of cells in all three regions are either broadly tuned or nonselective for these attributes. Nearly all cells respond to stimulus onset, a significant number also give a response to stimulus termination, and rarely a cell gives only off responses. Nearly all cells increase their discharge rate to visual stimuli. Receptive fields in the two retinotopically mapped regions, PI and PL, have well-defined borders. The sizes of these receptive fields show a positive correlation with the eccentricity of the receptive fields. The receptive fields in the remaining region, Pdm, are frequently very large, but with these large fields excluded, show a similar correlation with eccentricity. All pulvinar cells tested (n = 20) were mapped in retinal coordinates; the receptive fields are positioned in relation to the retina. We found no cells with gaze-gated characteristics (2), nor cells mapped in a spatial coordinate system. The response latencies in PI and PL are shorter and less variable than the latencies in Pdm. Active use of a stimulus can produce an enhancement or attenuation of the visual response. Eye-movement modulation was found in all three subdivisions in about equal frequencies. Attentional modulation was common in Pdm and was rare in PI and PL. The modulation is spatially selective in Pdm and nonselective in PI for a small number of tested cells. These data demonstrate functional differences between Pdm and the other two areas and suggest that Pdm plays a role in selective visual attention, whereas PI and PL probably contribute to other aspects of visual perception.

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