Spatiotemporal organization of simple-cell receptive fields in the cat's striate cortex. II. Linearity of temporal and spatial summation

1993 ◽  
Vol 69 (4) ◽  
pp. 1118-1135 ◽  
Author(s):  
G. C. DeAngelis ◽  
I. Ohzawa ◽  
R. D. Freeman
Keyword(s):  
Receptive Field ◽  
Striate Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Spatial Summation ◽  
Direction Selectivity ◽  
Simple Cells ◽  
Tuning Curves ◽  
Spatiotemporal Receptive Field ◽  
Temporal And Spatial

1. We have tested the hypothesis that simple cells in the cat's visual cortex perform a linear spatiotemporal filtering of the visual image. To conduct this study we note that a visual neuron behaves linearly if the responses to small, brief flashes of light are mathematically related, via the Fourier transform, to the responses elicited by sinusoidal grating stimuli. 2. We have evaluated the linearity of temporal and spatial summation for 118 simple cells recorded from the striate cortex (area 17) of adult cats and kittens at ages 4 and 8 wk postnatal. These neurons represent a subset of the population of cells for which we have described the postnatal development of spatiotemporal receptive-field structure in the preceding paper. Spatiotemporal receptive-field profiles are constructed, with the use of a reverse correlation technique, from the responses to random sequences of small bar stimuli that are brighter or darker than the background. Fourier analysis of spatiotemporal receptive-field profiles yields linear predictions of the cells' spatial and temporal frequency tuning. These predicted responses are compared with spatial and temporal frequency tuning curves measured by the use of drifting, sinusoidal-luminance grating stimuli. 3. For most simple cells, there is good agreement between spatial and temporal frequency tuning curves predicted from the receptive-field profile and those measured by the use of sinusoidal gratings. These results suggest that both spatial and temporal summation within simple cells are approximately linear. There is a tendency for predicted tuning curves to be slightly broader than measured tuning curves, a finding that is consistent with the effects of a threshold nonlinearity at the output of these neurons. In some cases, however, predicted tuning curves deviate from measured responses only at low spatial and temporal frequencies. This cannot be explained by a simple threshold nonlinearity. 4. If linearity is assumed, it should be possible to predict the direction selectivity of simple cells from the structure of their spatiotemporal receptive-field profiles. For virtually all cells, linear predictions correctly determine the preferred direction of motion of a visual stimulus. However, the strength of the directional bias is typically underestimated by a factor of about two on the basis of linear predictions. Consideration of the expansive exponential nonlinearity revealed in the contrast-response function permits a reconciliation of the discrepancy between measured and predicted direction selectivity indexes. 5. Overall, these findings show that spatiotemporal receptive-field profiles obtained with the use of reverse correlation may be used to predict a variety of response properties for simple cells.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Strobe Rearing Reduces Direction Selectivity in Area 17 by Altering Spatiotemporal Receptive-Field Structure

1998 ◽  
Vol 80 (6) ◽  
pp. 2991-3004 ◽  
Author(s):  
Allen L. Humphrey ◽  
Alan B. Saul
Keyword(s):  
Receptive Field ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Field Structure ◽  
Area 17 ◽  
Directional Tuning ◽  
Simple Cells ◽  
Spatiotemporal Receptive Field

Humphrey, Allen L. and Alan B. Saul. Strobe rearing reduces direction selectivity in area 17 by altering spatiotemporal receptive-field structure. J. Neurophysiol. 80: 2991–3004, 1998. Direction selectivity in simple cells of cat area 17 is linked to spatiotemporal (S-T) receptive-field structure. S-T inseparable receptive fields display gradients of response timing across the receptive field that confer a preferred direction of motion. Receptive fields that are not direction selective lack gradients; they are S-T separable, displaying uniform timing across the field. Here we further examine this link using a developmental paradigm that disrupts direction selectivity. Cats were reared from birth to 8 mo of age in 8-Hz stroboscopic illumination. Direction selectivity in simple cells was then measured using gratings drifting at different temporal frequencies (0.25–16 Hz). S-T structure was assessed using stationary bars presented at different receptive-field positions, with bar luminance being modulated sinusoidally at different temporal frequencies. For each cell, plots of response phase versus bar position were fit by lines to characterize S-T inseparability at each temporal frequency. Strobe rearing produced a profound loss of direction selectivity at all temporal frequencies; only 10% of cells were selective compared with 80% in normal cats. The few remaining directional cells were selective over a narrower than normal range of temporal frequencies and exhibited weaker than normal direction selectivity. Importantly, the directional loss was accompanied by a virtual elimination of S-T inseparability. Nearly all cells were S-T separable, like nondirectional cells in normal cats. The loss was clearest in layer 4. Normally, inseparability is greatest there, and it correlates well ( r = 0.77) with direction selectivity; strobe rearing reduced inseparability and direction selectivity to very low values. The few remaining directional cells were inseparable. In layer 6 of normal cats, most direction-selective cells are only weakly inseparable, and there is no consistent relationship between the two measures. However, after strobe rearing, even the weak inseparability was eliminated along with direction selectivity. The correlated changes in S-T structure and direction selectivity were confirmed using conventional linear predictions of directional tuning based on responses to counterphasing bars and white noise stimuli. The developmental changes were permanent, being observed up to 12 yr after strobe rearing. The deficits were remarkably specific; strobe rearing did not affect spatial receptive-field structure, orientation selectivity, spatial or temporal frequency tuning, or general responsiveness to visual stimuli. These results provide further support for a critical role of S-T structure in determining direction selectivity in simple cells. Strobe rearing eliminates directional tuning by altering the timing of responses within the receptive field.

Spatial and temporal frequency tuning in striate cortex: functional uniformity and specializations related to receptive field eccentricity

2010 ◽  
Vol 31 (6) ◽  
pp. 1043-1062 ◽  
Author(s):  
Hsin-Hao Yu ◽  
Richa Verma ◽  
Yin Yang ◽  
Heath A. Tibballs ◽  
Leo L. Lui ◽  
...  
Keyword(s):  
Receptive Field ◽  
Striate Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency

Receptive-field characteristics of neurons in cat striate cortex: Changes with visual field eccentricity

1976 ◽  
Vol 39 (3) ◽  
pp. 512-533 ◽  
Author(s):  
J. R. Wilson ◽  
S. M. Sherman
Keyword(s):  
Visual Field ◽  
Receptive Field ◽  
Striate Cortex ◽  
Ocular Dominance ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Orientation Selectivity ◽  
Simple Cells ◽  
Complex Cells ◽  
Cat Striate Cortex

1. Receptive-field properties of 214 neurons from cat striate cortex were studied with particular emphasis on: a) classification, b) field size, c) orientation selectivity, d) direction selectivity, e) speed selectivity, and f) ocular dominance. We studied receptive fields located throughtout the visual field, including the monocular segment, to determine how receptivefield properties changed with eccentricity in the visual field.2. We classified 98 cells as "simple," 80 as "complex," 21 as "hypercomplex," and 15 in other categories. The proportion of complex cells relative to simple cells increased monotonically with receptive-field eccenticity.3. Direction selectivity and preferred orientation did not measurably change with eccentricity. Through most of the binocular segment, this was also true for ocular dominance; however, at the edge of the binocular segment, there were more fields dominated by the contralateral eye.4. Cells had larger receptive fields, less orientation selectivity, and higher preferred speeds with increasing eccentricity. However, these changes were considerably more pronounced for complex than for simple cells.5. These data suggest that simple and complex cells analyze different aspects of a visual stimulus, and we provide a hypothesis which suggests that simple cells analyze input typically from one (or a few) geniculate neurons, while complex cells receive input from a larger region of geniculate neurons. On average, this region is invariant with eccentricity and, due to a changing magnification factor, complex fields increase in size with eccentricity much more than do simple cells. For complex cells, computations of this geniculate region transformed to cortical space provide a cortical extent equal to the spread of pyramidal cell basal dendrites.

Comparison of contrast-normalization and threshold models of the responses of simple cells in cat striate cortex

1997 ◽  
Vol 14 (2) ◽  
pp. 293-309 ◽  
Author(s):  
D. J. Tolhurst ◽  
D. J. Heeger
Keyword(s):  
Receptive Field ◽  
Striate Cortex ◽  
Frequency Tuning ◽  
Tuning Curve ◽  
Threshold Model ◽  
Output Stage ◽  
Simple Cells ◽  
Neurophysiological Data ◽  
Contrast Normalization ◽  
The Relationship

AbstractIn almost every study of the linearity of spatiotemporal summation in simple cells of the cat's visual cortex, there have been systematic mismatches between the experimental observations and the predictions of the linear theory. These mismatches have generally been explained by supposing that the initial spatiotemporal summation stage is strictly linear, but that the following output stage of the simple cell is subject to some contrast-dependent nonlinearity. Two main models of the output nonlinearity have been proposed: the threshold model (e.g. Tolhurst & Dean, 1987) and the contrast-normalization model (e.g. Heeger, 1992a, b). In this paper, the two models are fitted rigorously to a variety of previously published neurophysiological data, in order to determine whether one model is a better explanation of the data. We reexamine data on the interaction between two bar stimuli presented in different parts of the receptive field; on the relationship between the receptive-field map and the inverse Fourier transform of the spatial-frequency tuning curve; on the dependence of response amplitude and phase on the spatial phase of stationary gratings; on the relationships between the responses to moving and modulated gratings; and on the suppressive action of gratings moving in a neuron's nonpreferred direction. In many situations, the predictions of the two models are similar, but the contrast-normalization model usually fits the data slightly better than the threshold model, and it is easier to apply the equations of the normalization model. More importantly, the normalization model is naturally able to account very well for the details and subtlety of the results in experiments where the total contrast energy of the stimuli changes; some of these phenomena are completely beyond the scope of the threshold model. Rigorous application of the models' equations has revealed some situations where neither model fits quite well enough, and we must suppose, therefore, that there are some subtle nonlinearities still to be characterized.

Length and width tuning of neurons in the cat's primary visual cortex

1994 ◽  
Vol 71 (1) ◽  
pp. 347-374 ◽  
Author(s):  
G. C. DeAngelis ◽  
R. D. Freeman ◽  
I. Ohzawa
Keyword(s):  
Receptive Field ◽  
Spatial Frequency ◽  
Spatial Organization ◽  
Striate Cortex ◽  
Frequency Tuning ◽  
Variable Parameter ◽  
Visual Space ◽  
Similar Degree ◽  
Tuning Curves ◽  
Number Of Cycles

1. The classically defined receptive field of a visual neuron is the area of visual space over which the cell responds to visual stimuli. It is well established, however, that the discharge produced by an optimal stimulus can be modulated by the presence of additional stimuli that by themselves do not produce any response. This study examines inhibitory influences that originate from areas located outside of the classical (i.e., excitatory) receptive field. Previous work has shown that for some cells the response to a properly oriented bar of light becomes attenuated when the bar extends beyond the receptive field, a phenomenon known as end-inhibition (or length tuning). Analogously, it has been shown that increasing the number of cycles of a drifting grating stimulus may also inhibit the firing of some cells, an effect known as side-inhibition (or width tuning). Very little information is available, however, about the relationship between end- and side-inhibition. We have examined the spatial organization and tuning characteristics of these inhibitory effects by recording extracellularly from single neurons in the cat's striate cortex (Area 17). 2. For each cortical neuron, length and width tuning curves were obtained with the use of rectangular patches of drifting sinusoidal gratings that have variable length and width. Results from 82 cells show that the strengths of end- and side-inhibition tend to be correlated. Most cells that exhibit clear end-inhibition also show a similar degree of side-inhibition. For these cells, the excitatory receptive field is surrounded on all sides by inhibitory zones. Some cells exhibit only end- or side-inhibition, but not both. Data for 28 binocular cells show that length and width tuning curves for the dominant and nondominant eyes tend to be closely matched. 3. We also measured tuning characteristics of end- and side-inhibition. To obtain these data, the excitatory receptive field was stimulated with a grating patch having optimal orientation, spatial frequency, and size, whereas the end- or side-inhibitory regions were stimulated with patches of gratings that had a variable parameter (such as orientation). Results show that end- and side-inhibition tend to be strongest at the orientation and spatial frequency that yield maximal excitation. However, orientation and spatial frequency tuning curves for inhibition are considerably broader than those for excitation, suggesting that inhibition is mediated by a pool of neurons.(ABSTRACT TRUNCATED AT 400 WORDS)

Contrast-Dependent Changes in Spatial Frequency Tuning of Macaque V1 Neurons: Effects of a Changing Receptive Field Size

2002 ◽  
Vol 88 (3) ◽  
pp. 1363-1373 ◽  
Author(s):  
Michael P. Sceniak ◽  
Michael J. Hawken ◽  
Robert Shapley
Keyword(s):  
Receptive Field ◽  
Spatial Frequency ◽  
Frequency Tuning ◽  
Fundamental Property ◽  
Spatial Summation ◽  
Field Size ◽  
Stimulus Contrast ◽  
Tuning Curves ◽  
Spatial Frequency Tuning ◽  
Receptive Field Organization

Previous studies on single neurons in primary visual cortex have reported that selectivity for orientation and spatial frequency tuning do not change with stimulus contrast. The prevailing hypothesis is that contrast scales the response magnitude but does not differentially affect particular stimuli. Models where responses are normalized over contrast to maintain constant tuning for parameters such as orientation and spatial frequency have been proposed to explain these results. However, our results indicate that a fundamental property of receptive field organization, spatial summation, is not contrast invariant. We examined the spatial frequency tuning of cells that show contrast-dependent changes in spatial summation and have found that spatial frequency selectivity also depends on stimulus contrast. These results indicate that contrast changes in the spatial frequency tuning curves result from spatial reorganization of the receptive field.

Spatiotemporal Frequency Tuning Dynamics of Neurons in the Owl Visual Wulst

2010 ◽  
Vol 103 (6) ◽  
pp. 3424-3436 ◽  
Author(s):  
Lucas Pinto ◽  
Jerome Baron
Keyword(s):  
Striate Cortex ◽  
Frequency Tuning ◽  
Temporal Frequency ◽  
Broad Band ◽  
Low Frequency ◽  
Emergent Properties ◽  
Response Latencies ◽  
Tuning Curves ◽  
Low Pass ◽  
Spatiotemporal Tuning

The transformation of spatial (SF) and temporal frequency (TF) tuning functions from broad-band/low-pass to narrow band-pass profiles is one of the key emergent properties of neurons in the mammalian primary visual cortex (V1). The mechanisms underlying such transformation are still a matter of ongoing debate. With the aim of providing comparative insights into the issue, we analyzed various aspects of the spatiotemporal tuning dynamics of neurons in the visual wulst of four awake owls. The wulst is the avian telencephalic target of the retinothalamofugal pathway and, in owls, bears striking functional analogy with V1. Most neurons in our sample exhibited fast and large-magnitude adaptation to the visual stimuli with response latencies very similar to those reported for V1. Moreover, latency increased as a function of stimulus SF but not TF, which suggests that parvo- and magno-like geniculate inputs could be converging onto single wulst neurons. No net shifts in preferred SF or TF were observed along the initial second of stimulation, but bandwidth decreased roughly during the first 200 ms after response latency for both stimulus dimensions. For SF, this occurred exclusively as a consequence of low-frequency suppression, whereas suppression was observed both at the low- and high-frequency limbs of TF tuning curves. Overall these results indicate that SF and TF tuning curves in the wulst are shaped by both feedforward and intratelencephalic suppressive mechanisms, similarly to what seems to be the case in the mammalian striate cortex.

Inhibitory Contributions to Spatiotemporal Receptive-Field Structure and Direction Selectivity in Simple Cells of Cat Area 17

1999 ◽  
Vol 81 (3) ◽  
pp. 1212-1224 ◽  
Author(s):  
Aditya Murthy ◽  
Allen L. Humphrey
Keyword(s):  
Receptive Field ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Field Structure ◽  
Area 17 ◽  
Directional Tuning ◽  
Simple Cells ◽  
Layer 4 ◽  
Two Measures ◽  
Spatiotemporal Receptive Field

Inhibitory contributions to spatiotemporal receptive-field structure and direction selectivity in simple cells of cat area 17. Intracortical inhibition contributes to direction selectivity in primary visual cortex, but how it acts has been unclear. We investigated this problem in simple cells of cat area 17 by taking advantage of the link between spatiotemporal (S-T) receptive-field structure and direction selectivity. Most cells in layer 4 have S-T–oriented receptive fields in which gradients of response timing across the field confer a preferred direction of motion. Linear summation of responses across the receptive field, followed by a static nonlinear amplification, has been shown previously to account for directional tuning in layer 4. We tested the hypotheses that inhibition acts by altering S-T structure or the static nonlinearity or both. Drifting and counterphasing sinewave gratings were used to measure direction selectivity and S-T structure, respectively, in 17 layer 4 simple cells before and during iontophoresis of bicuculline methiodide (BMI), a GABAA antagonist. S-T orientation was quantified from fits to response temporal phase versus stimulus spatial phase data. Bicuculline reduced direction selectivity and S-T orientation in nearly all cells, and reductions in the two measures were well correlated ( r = 0.81) and reversible. Using conventional linear predictions based on response phase and amplitude, we found that BMI-induced changes in S-T structure also accounted well for absolute changes in the amplitude and phase of responses to gratings drifting in the preferred and nonpreferred direction. For each cell we also calculated an exponent used to estimate the static nonlinearity. Bicuculline reduced the exponent in most cells, but the changes were not correlated with reductions in direction selectivity. We conclude that GABAA-mediated inhibition influences directional tuning in layer 4 primarily by sculpting S-T receptive-field structure. The source of the inhibition is likely to be other simple cells with certain spatiotemporal relationships to their target. Despite reductions in the two measures, most receptive fields maintained some directional tuning and S-T orientation during BMI. This suggests that their excitatory inputs, arising from the lateral geniculate nucleus and within area 17, are sufficient to create some S-T orientation and that inhibition accentuates it. Finally, BMI also reduced direction selectivity in 8 of 10 simple cells tested in layer 6, but the reductions were not accompanied by systematic changes in S-T structure. This reflects the fact that S-T orientation, as revealed by our first-order measures of the receptive field, is weak there normally. Inhibition likely affects layer 6 cells via more complex, nonlinear interactions.

Motion selectivity and the contrast-response function of simple cells in the visual cortex

1991 ◽  
Vol 7 (6) ◽  
pp. 531-546 ◽  
Author(s):  
Duane G. Albrecht ◽  
Wilson S. Geisler
Keyword(s):  
Visual Cortex ◽  
Receptive Field ◽  
Response Function ◽  
Gain Control ◽  
Direction Selectivity ◽  
Metabolic Energy ◽  
Simple Cells ◽  
Contrast Response Function ◽  
Spatiotemporal Receptive Field ◽  
Contrast Response

AbstractThe responses of simple cells were recorded from the visual cortex of cats, as a function of the position and contrast of counterphase and drifting grating patterns, to assess whether direction selectivity can be accounted for on the basis of linear summation. The expected responses to a counterphase grating, given a strictly linear model, would be the sum of the responses to the two drifting components. The measured responses were not consistent with the linear prediction. For example, nearly all cells showed two positions where the responses approached zero (i.e. two “null phase positions”); this was true, even for the most direction selective cells. However, the measured responses were consistent with the hypothesis that direction selectivity is a consequence of the linear spatiotemporal receptive-field structure, coupled with the nonlinearities revealed by the contrast-response function: contrast gain control, halfwave rectification, and expansive exponent. When arranged in a particular sequence, each of these linear and nonlinear mechanisms performs a useful function in a general model of simple cells. The linear spatiotemporal receptive field initiates stimulus selectivity (for direction, orientation, spatial frequency, etc.). The expansive response exponent enhances selectivity. The contrast-set gain control maintains selectivity (over a wide range of contrasts, in spite of the limited dynamic response range and steep slope of the contrast-response function). Rectification conserves metabolic energy.

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