Contrast sensitivity of MT receptive field centers and surrounds

Neurons throughout the visual system have receptive fields with both excitatory and suppressive components. The latter are responsible for a phenomenon known as surround suppression, in which responses decrease as a stimulus is extended beyond a certain size. Previous work has shown that surround suppression in the primary visual cortex depends strongly on stimulus contrast. Such complex center-surround interactions are thought to relate to a variety of functions, although little is known about how they affect responses in the extrastriate visual cortex. We have therefore examined the interaction of center and surround in the middle temporal (MT) area of the macaque ( Macaca mulatta) extrastriate cortex by recording neuronal responses to stimuli of different sizes and contrasts. Our findings indicate that surround suppression in MT is highly contrast dependent, with the strongest suppression emerging unexpectedly at intermediate stimulus contrasts. These results can be explained by a simple model that takes into account the nonlinear contrast sensitivity of the neurons that provide input to MT. The model also provides a qualitative link to previous reports of a topographic organization of area MT based on clusters of neurons with differing surround suppression strength. We show that this organization can be detected in the gamma-band local field potentials (LFPs) and that the model parameters can predict the contrast sensitivity of these LFP responses. Overall our results show that surround suppression in area MT is far more common than previously suspected, highlighting the potential functional importance of the accumulation of nonlinearities along the dorsal visual pathway.

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The Effect of Attention on Neuronal Responses to High and Low Contrast Stimuli

Journal of Neurophysiology ◽

10.1152/jn.01019.2009 ◽

2010 ◽

Vol 104 (2) ◽

pp. 960-971 ◽

Cited By ~ 24

Author(s):

Joonyeol Lee ◽

John H. R. Maunsell

Keyword(s):

Cerebral Cortex ◽

Visual Cortex ◽

Rhesus Monkeys ◽

Receptive Fields ◽

Visual Area ◽

Neuronal Responses ◽

Attentional Modulation ◽

Low Contrast ◽

Middle Temporal ◽

Visual Area Mt

It remains unclear how attention affects the tuning of individual neurons in visual cerebral cortex. Some observations suggest that attention preferentially enhances responses to low contrast stimuli, whereas others suggest that attention proportionally affects responses to all stimuli. Resolving how attention affects responses to different stimuli is essential for understanding the mechanism by which it acts. To explore the effects of attention on stimuli of different contrasts, we recorded from individual neurons in the middle temporal visual area (MT) of rhesus monkeys while shifting their attention between preferred and nonpreferred stimuli within their receptive fields. This configuration results in robust attentional modulation that makes it possible to readily distinguish whether attention acts preferentially on low contrast stimuli. We found no evidence for greater enhancement of low contrast stimuli. Instead, the strong attentional modulations were well explained by a model in which attention proportionally enhances responses to stimuli of all contrasts. These data, together with observations on the effects of attention on responses to other stimulus dimensions, suggest that the primary effect of attention in visual cortex may be to simply increase the strength of responses to all stimuli by the same proportion.

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Unifying Temporal Phenomena in Human Visual Cortex

10.1101/108639 ◽

2017 ◽

Cited By ~ 1

Author(s):

Jingyang Zhou ◽

Noah C. Benson ◽

Kendrick Kay ◽

Jonathan Winawer

Keyword(s):

Visual Cortex ◽

Receptive Field ◽

Temporal Dynamics ◽

Gain Control ◽

Spatial Vision ◽

Research Area ◽

Neuronal Responses ◽

Stimulus Contrast ◽

Temporal Properties ◽

Cortical Responses

AbstractNeuronal responses in visual cortex show a diversity of complex temporal properties. These properties include sub-additive temporal summation, response reduction with repeated or sustained stimuli (adaptation), and slower dynamics at low stimulus contrast. Here, we hypothesize that these seemingly disparate effects can be explained by a single, shared computational mechanism. We propose a model consisting of a linear stage, followed by history-dependent gain control. The model accounts for these various temporal phenomena, tested against an unusually diverse set of measurements - intracranial electrodes in patients, fMRI, and macaque single unit spiking. The model further enables us to uncover a systematic and rich variety of temporal encoding strategies across visual cortex: First, temporal receptive field shape differs both across and within visual field maps. Second, later visual areas show more rapid and pronounced adaptation. Our study provides a new framework to understand the transformation between visual input and dynamical cortical responses.Author SummaryThe nervous system extracts meaning from the distribution of light over space and time. Spatial vision has been a highly successful research area, and the spatial receptive field has served as a fundamental and unifying concept that spans perception, computation, and physiology. While there has also been a large interest in temporal vision, the temporal domain has lagged the spatial domain in terms of quantitative models of how signals are transformed across the visual hierarchy. Here we present a model of temporal dynamics of neuronal responses in human cerebral cortex. We show that the model can accurately predict responses at the millisecond scale using intracortical electrodes in patient volunteers, and that the same model generalizes to multiple types of other measurements, including functional MRI and action potentials from monkey cortex. Further, we show that a single model can account for a variety of temporal phenomena, including short-term adaptation and slower dynamics at low stimulus contrast. By developing a computational model and showing that it successfully generalizes across measurement types, cortical areas, and stimuli, we provide new insights into how time-varying images are encoded and transformed into dynamic cortical responses.

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Contrast Dependence of Response Normalization in Area MT of the Rhesus Macaque

Journal of Neurophysiology ◽

10.1152/jn.00255.2002 ◽

2002 ◽

Vol 88 (6) ◽

pp. 3398-3408 ◽

Cited By ~ 75

Author(s):

Hilary W. Heuer ◽

Kenneth H. Britten

Keyword(s):

Receptive Field ◽

Rhesus Macaque ◽

Extrastriate Cortex ◽

Neuronal Responses ◽

Stimulus Contrast ◽

Linear Summation ◽

Middle Temporal ◽

Good Account ◽

Rapid Transition ◽

Contrast Normalization

Contrast normalization is a process whereby responses of neurons are scaled according to the total amount of contrast in a region of the image nearby the receptive field of a neuron. This process allows neurons to code for informative scene or object attributes in a manner unaffected by changes in illumination. Evidence for normalization is seen in striate and extrastriate cortex from experiments where multiple stimuli are presented with a single receptive field (RF). Neuronal responses in such experiments are smaller than that predicted by linear summation, revealing the presence of normalization. While the presence of normalization is often clear, its mechanism is less so. To study the mechanism of normalization, we measured the interaction between pairs of brief local stimuli (spatial Gabor functions) within the RFs of cells in the middle temporal (MT or V5) area of monkeys and varied both the location and contrast of the stimuli. We found response summed approximately linearly when contrast was low but rapidly became normalized as stimulus contrast increased. The rapid transition to effective normalization at low contrasts suggested cooperativity in the normalization, and a model embodying such a cooperative step provided a good account of our data.

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A twisted visual field map in the primate cortex predicted by topographic continuity

10.1101/682187 ◽

2019 ◽

Author(s):

Hsin-Hao Yu ◽

Declan P. Rowley ◽

Nicholas S.C. Price ◽

Marcello G.P. Rosa ◽

Elizabeth Zavitz

Keyword(s):

Visual Cortex ◽

Visual Field ◽

Receptive Fields ◽

Electrode Array ◽

Extrastriate Cortex ◽

Complex Type ◽

Retinotopic Maps ◽

Visual Areas ◽

Array Recordings ◽

Retinotopic Map

AbstractAdjacent neurons in visual cortex have overlapping receptive fields within and across area boundaries, an arrangement which is theorized to minimize wiring cost. This constraint is thought to create retinotopic maps of opposing field sign (mirror and non-mirror representations of the visual field) in adjacent visual areas, a concept which has become central in current attempts to subdivide the cortex. We modelled a realistic developmental scenario in which adjacent areas do not mature simultaneously, but need to maintain topographic continuity across their borders. This showed that the same mechanism that is hypothesized to maintain topographic continuity within each area can lead to a more complex type of retinotopic map, consisting of sectors with opposing field sign within a same area. Using fully quantitative electrode array recordings, we then demonstrate that this type of map exists in the primate extrastriate cortex.

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Constraints on the Source of Short-Term Motion Adaptation in Macaque Area MT. I. The Role of Input and Intrinsic Mechanisms

Journal of Neurophysiology ◽

10.1152/jn.00852.2001 ◽

2002 ◽

Vol 88 (1) ◽

pp. 354-369 ◽

Cited By ~ 90

Author(s):

Nicholas J. Priebe ◽

Mark M. Churchland ◽

Stephen G. Lisberger

Keyword(s):

Firing Rate ◽

Time Course ◽

Receptive Fields ◽

Visual Space ◽

Extrastriate Cortex ◽

Target Velocity ◽

Short Term ◽

Cellular Mechanisms ◽

Area Mt ◽

Short Term Adaptation

Neurons in area MT, a motion-sensitive area of extrastriate cortex, respond to a step of target velocity with a transient-sustained firing pattern. The transition from a high initial firing rate to a lower sustained rate occurs over a time course of 20–80 ms and is considered a form of short-term adaptation. The present paper asks whether adaptation is due to input-specific mechanisms such as short-term synaptic depression or if it results from intrinsic cellular mechanisms such as spike-rate adaptation. We assessed the contribution of input-specific mechanisms by using a condition/test paradigm to measure the spatial scale of adaptation. Conditioning and test stimuli were placed within MT receptive fields but were spatially segregated so that the two stimuli would activate different populations of inputs from the primary visual cortex (V1). Conditioning motion at one visual location caused a reduction of the transient firing to subsequent test motion at a second location. The adaptation field, estimated as the region of visual space where conditioning motion caused adaptation, was always larger than the MT receptive field. Use of the same stimulus configuration while recording from direction-selective neurons in V1 failed to demonstrate either adaptation or the transient-sustained response pattern that is the signature of short-term adaptation in MT. We conclude that the shift from transient to sustained firing in MT cells does not result from an input-specific mechanism applied to inputs from V1 because it operates over a wider range of the visual field than is covered by receptive fields of V1 neurons. We used a direct analysis of MT neuron spike trains for many repetitions of the same motion stimulus to assess the contribution to adaptation of intrinsic cellular mechanisms related to spiking. On a trial-by-trial basis, there was no correlation between number of spikes in the transient interval and the interval immediately after the transient period. This is opposite the prediction that there should be a correlation if spikes cause adaptation directly. Further, the transient was suppressed or extinguished, not delayed, in trials in which the neuron emitted zero spikes during the interval that showed a transient in average firing rate. We conclude that the transition from transient to sustained firing in neurons in area MT is caused by mechanisms that are neither input-specific nor controlled by the spiking of the adapting neuron. We propose that the short-term adaptation observed in area MT emerges from the intracortical circuit within MT.

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Population receptive fields of human primary visual cortex organised as DC-balanced bandpass filters

Scientific Reports ◽

10.1038/s41598-021-01891-2 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Daniel Gramm Kristensen ◽

Kristian Sandberg

Keyword(s):

Visual Cortex ◽

Primary Visual Cortex ◽

Visual Stimulation ◽

Receptive Fields ◽

Bandpass Filters ◽

Model Complexity ◽

Stimulus Contrast ◽

Mathematical Basis ◽

Dc Offset ◽

Difference Of Gaussians

AbstractThe response to visual stimulation of population receptive fields (pRF) in the human visual cortex has been modelled with a Difference of Gaussians model, yet many aspects of their organisation remain poorly understood. Here, we examined the mathematical basis and signal-processing properties of this model and argue that the DC-balanced Difference of Gaussians (DoG) holds a number of advantages over a DC-biased DoG. Through functional magnetic resonance imaging (fMRI) pRF mapping, we compared performance of DC-balanced and DC-biased models in human primary visual cortex and found that when model complexity is taken into account, the DC-balanced model is preferred. Finally, we present evidence indicating that the BOLD signal DC offset contains information related to the processing of visual stimuli. Taken together, the results indicate that V1 pRFs are at least frequently organised in the exact constellation that allows them to function as bandpass filters, which makes the separation of stimulus contrast and luminance possible. We further speculate that if the DoG models stimulus contrast, the DC offset may reflect stimulus luminance. These findings suggest that it may be possible to separate contrast and luminance processing in fMRI experiments and this could lead to new insights on the haemodynamic response.

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Neural Field Model of Receptive Field Restructuring in Primary Visual Cortex

Neural Computation ◽

10.1162/089976601300014664 ◽

2001 ◽

Vol 13 (1) ◽

pp. 139-159 ◽

Cited By ~ 8

Author(s):

Katrin Suder ◽

Florentin Wörgötter ◽

Thomas Wennekers

Keyword(s):

Visual Cortex ◽

Membrane Potential ◽

Receptive Field ◽

Receptive Fields ◽

Neural Field ◽

Potential Profile ◽

Model Parameters ◽

Neural Field Model ◽

State Dependent ◽

The Individual

Receptive fields (RF) in the visual cortex can change their size depending on the state of the individual. This reflects a changing visual resolution according to different demands on information processing during drowsiness. So far, however, the possible mechanisms that underlie these size changes have not been tested rigorously. Only qualitatively has it been suggested that state-dependent lateral geniculate nucleus (LGN) firing patterns (burst versus tonic firing) are mainly responsible for the observed cortical receptive field restructuring. Here, we employ a neural field approach to describe the changes of cortical RF properties analytically. Expressions to describe the spatiotemporal receptive fields are given for pure feedforward networks. The model predicts that visual latencies increase nonlinearly with the distance of the stimulus location from the RF center. RF restructuring effects are faithfully reproduced. Despite the changing RF sizes, the model demonstrates that the width of the spatial membrane potential profile (as measured by the variance σ of a gaussian) remains constant in cortex. In contrast, it is shown for recurrent networks that both the RF width and the width of the membrane potential profile generically depend on time and can even increase if lateral cortical excitatory connections extend further than fibers from LGN to cortex. In order to differentiate between a feedforward and a recurrent mechanism causing the experimental RF changes, we fitted the data to the analytically derived point-spread functions. Results of the fits provide estimates for model parameters consistent with the literature data and support the hypothesis that the observed RF sharpening is indeed mainly driven by input from LGN, not by recurrent intracortical connections.

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A twisted visual field map in the primate dorsomedial cortex predicted by topographic continuity

Science Advances ◽

10.1126/sciadv.aaz8673 ◽

2020 ◽

Vol 6 (44) ◽

pp. eaaz8673

Author(s):

Hsin-Hao Yu ◽

Declan P. Rowley ◽

Nicholas S. C. Price ◽

Marcello G. P. Rosa ◽

Elizabeth Zavitz

Keyword(s):

Visual Cortex ◽

Visual Field ◽

Receptive Fields ◽

Electrode Array ◽

Extrastriate Cortex ◽

Complex Type ◽

Retinotopic Maps ◽

Array Recordings

Adjacent neurons in visual cortex have overlapping receptive fields within and across area boundaries, an arrangement theorized to minimize wiring cost. This constraint is traditionally thought to create retinotopic maps of opposing field signs (mirror and nonmirror visual field representations) in adjacent areas, a concept that has become central in current attempts to subdivide the extrastriate cortex. We simulated the formation of retinotopic maps using a model that balances constraints imposed by smoothness in the representation within an area and by congruence between areas. As in the primate cortex, this model usually leads to alternating mirror and nonmirror maps. However, we found that it can also produce a more complex type of map, consisting of sectors with opposing field sign within a single area. Using fully quantitative electrode array recordings, we then demonstrate that this type of inhomogeneous map exists in the controversial dorsomedial region of the primate extrastriate cortex.

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