Evidence of input from lagged cells in the lateral geniculate nucleus to simple cells in cortical area 17 of the cat

1992 ◽  
Vol 68 (4) ◽  
pp. 1190-1208 ◽  
Author(s):  
A. B. Saul ◽  
A. L. Humphrey
Keyword(s):  
Receptive Field ◽  
Lateral Geniculate Nucleus ◽  
Temporal Frequency ◽  
Receptive Fields ◽  
Area 17 ◽  
Cortical Cells ◽  
Simple Cells ◽  
Absolute Phase ◽  
Phase Lags ◽  
Lagged Cells

1. The visual cortex receives several types of afferents from the lateral geniculate nucleus (LGN) of the thalamus. In the cat, previous work studied the ON/OFF and X/Y distinctions, investigating their convergence and segregation in cortex. Here we pursue the lagged/nonlagged dichotomy as it applies to simple cells in area 17. Lagged and nonlagged cells in the A-layers of the LGN can be distinguished by the timing of their responses to sinusoidally luminance-modulated stimuli. We therefore used similar stimuli in cortex to search for signs of lagged and nonlagged inputs to cortical cells. 2. Line-weighting functions were obtained from 37 simple cells. A bar was presented at a series of positions across the receptive field, with the luminance of the bar modulated sinusoidally at a series of temporal frequencies. First harmonic response amplitude and phase values for each position were plotted as a function of temporal frequency. Linear regression on the phase versus temporal frequency data provided estimates of latency (slope) and absolute phase (intercept) for each receptive-field position tested. These two parameters were previously shown to distinguish between lagged and nonlagged LGN cells. Lagged cells generally have latencies > 100 ms and absolute phase lags; nonlagged cells have latencies < 100 ms and absolute phase leads. With the use of these criteria, we classified responses at discrete positions inside cortical receptive fields as lagged-like and nonlagged-like. 3. Both lagged-like and nonlagged-like responses were observed. The majority of cortical cells had only or nearly only nonlagged-like zones. In 15 of the 37 cells, however, the receptive field consisted of > or = 20% lagged-like zones. For eight of these cells, lagged-like responses predominated. 4. The distribution of latency and absolute phase across the sample of cortical simple cell receptive fields resembled the distribution for LGN cells. The resemblance was especially striking when only cells in or adjacent to geniculate recipient layers were considered. Absolute phase lags were almost uniformly associated with long latencies. Absolute phase leads were generally associated with short latencies, although cortical cells responded with long latencies and absolute phase leads slightly more often than LGN cells. 5. Cells in which a high percentage of lagged-like responses were observed had a restricted laminar localization, with all but two being found in layer 4B or 5A. Cells with predominantly nonlagged-like responses were found in all layers. 6. Lagged-like zones can not be easily explained as a result of stimulating combinations of nonlagged inputs.(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 properties of neurons in the monkey striate cortex

1987 ◽  
Vol 231 (1263) ◽  
pp. 251-288 ◽  
Keyword(s):  
Receptive Field ◽  
Contrast Sensitivity ◽  
Visual Processing ◽  
Striate Cortex ◽  
Receptive Fields ◽  
Spatial Filter ◽  
Cortical Cells ◽  
Simple Cells ◽  
Gabor Function ◽  
Difference Of Gaussians

Contrast sensitivity as a function of spatial frequency was determined for 138 neurons in the foveal region of primate striate cortex. The accuracy of three models in describing these functions was assessed by the method of least squares. Models based on difference-of-Gaussians (DOG) functions were shown to be superior to those based on the Gabor function or the second differential of a Gaussian. In the most general case of the DOG models, each subregion of a simple cell’s receptive field was constructed from a single DOG function. All the models are compatible with the classical observation that the receptive fields of simple cells are made up of spatially discrete ‘on’ and ‘off’ regions. Although the DOG-based models have more free parameters, they can account better for the variety of shapes of spatial contrast sensitivity functions observed in cortical cells and, unlike other models, they provide a detailed description of the organization of subregions of the receptive field that is consistent with the physiological constraints imposed by earlier stages in the visual pathway. Despite the fact that the DOG-based models have spatially discrete components, the resulting amplitude spectra in the frequency domain describe complex cells just as well as simple cells. The superiority of the DOG-based models as a primary spatial filter is discussed in relation to popular models of visual processing that use the Gabor function or the second differential of a Gaussian.

Spatiotemporal mechanisms in receptive fields of visual cortical simple cells: a model

1991 ◽  
Vol 65 (3) ◽  
pp. 494-510 ◽  
Author(s):  
F. Worgotter ◽  
G. Holt
Keyword(s):  
Receptive Field ◽  
Receptive Fields ◽  
Sine Wave ◽  
Central Feature ◽  
Cortical Cells ◽  
Stimulus Motion ◽  
Simple Cells ◽  
Preferred Direction ◽  
Low Pass ◽  
The Impact

1. Simple cells in the visual cortex have been subdivided into nondirection-selective (NDS), direction asymmetric (DA), and direction-selective (DS) cells. DA cells reverse their preferred direction with reversal of the stimulus contrast; DS2 cells respond with the same preferred direction for light and dark stimuli, whereas DS1 cells respond only to one (light or dark) contrast. Also, four velocity response groups have been distinguished: velocity broadband, low-pass, high-pass, and -tuned cells. This study describes an analytic model of feed-forward spatiotemporal interactions within a receptive field that reproduces these basic features of cortical simple cell behavior in the cat. 2. The spatial structure of the receptive fields is simulated with Gabor functions. Two neurobiologically plausible mechanisms, temporal low-pass filtering and intracortical spatial distribution of activity, are modeled. The central feature of the study is the implementation of both mechanisms in a spatially continuous way. The model is analytic, but an equivalent neural network diagram was drawn and is used to explain the features of the model. 3. First-order temporal low-pass filtering is performed both after convolving the stimulus light-intensity function with the Gabor type receptive field and also at the final output step of the model. In the circuit diagram this would correspond to low-pass filtering in lateral geniculate nucleus (LGN) and cortical cells. Filtering was adjusted to have a -3-dB drop-off frequency of 2-3 Hz, corresponding to the drop-off frequencies observed in response to temporal modulation of sine-wave gratings. 4. The mechanism that we call intracortical distribution of activity is implemented along the axis of stimulus motion. A response elicited from the part of the receptive field that is stimulated at a given time will spread out in the receptive field, influencing regions that have not been stimulated. It is equivalent to spreading of activity on the cortical surface. This mechanism extends the existing ideas of discrete interactions between subfields to a continuous scheme throughout the whole receptive field. It is based on findings that intracortical interactions exist even within single subfields. The impact of distributing the activity is assumed to decrease exponentially with the Euclidian distance between the stimulated region and the region under consideration. 5. Thresholds are implemented only at the level of the cortex. Both the activity distributing mechanism and the output of the cell being studied are thresholded.(ABSTRACT TRUNCATED AT 400 WORDS)

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.

Strobe Rearing Prevents the Convergence of Inputs With Different Response Timings Onto Area 17 Simple Cells

1998 ◽  
Vol 80 (6) ◽  
pp. 3005-3020 ◽  
Author(s):  
Allen L. Humphrey ◽  
Alan B. Saul ◽  
Jordan C. Feidler
Keyword(s):  
Single Cells ◽  
Receptive Fields ◽  
Direction Selectivity ◽  
Area 17 ◽  
Simple Cells ◽  
Absolute Phase ◽  
Wide Range ◽  
The Mean ◽  
Different Response ◽  
Response Timing

Humphrey, Allen L., Alan B. Saul, and Jordan C. Feidler. Strobe rearing prevents the convergence of inputs with different response timings onto area 17 simple cells. J. Neurophysiol. 80: 3005–3020, 1998. The preceding paper showed that the loss of direction selectivity in simple cells induced by strobe rearing reflects the elimination of spatially ordered response timing differences across the receptive field that underlie spatiotemporal (S-T) inseparability. Here we addressed whether these changes reflected an elimination of certain timings or an alteration in how timings were associated in single cells. Timing in receptive fields was measured using stationary bars undergoing sinusoidal luminance modulation at different temporal frequencies (0.5–6 Hz). For each bar position, response phase versus temporal frequency data were fit by a line to obtain two measures: absolute phase and latency. In normal cats, many individual simple cells display a wide range of timings; in layer 4, the mean range for absolute phase and latency was 0.21 cycles and 39 ms, respectively. Strobe rearing compressed the mean timing ranges in single cells, to 0.08 cycles and 31 ms, respectively, and this compression accounted for the loss of inseparability. A similar compression was measured in layer 6 cells. In contrast, the range of timing values across the simple-cell population was relatively normal. Single cells merely sampled narrower than normal regions of the timing space. We sought to understand these cortical changes in terms of how inputs from the lateral geniculate nucleus (LGN) may have been affected by strobe rearing. In normal cats, a wide range of absolute phase and latency values exists among lagged and nonlagged LGN cells, and these thalamic timings account for most of the cortical timings. Also, S-T inseparability in many simple cells can be attributed to the convergence of lagged and/or nonlagged inputs. Strobe rearing did not change the sampling of lagged and nonlagged cells, and the geniculate timings continued to account for most of the cortical timings. However, strobe rearing virtually eliminated cortical receptive fields with mixed lagged and nonlagged timing, and it compressed the timing range in cells dominated by one or the other geniculate type. Thus strobe rearing did not eliminate certain timings in LGN or cortex, but prevented the convergence of different timings on single cells. To account for these results, we propose a developmental model in which strobe stimulation alters the correlational structure of inputs based on their response timing. Only inputs with similar timing become associated on single cortical cells, and this produces S-T separable receptive fields that lack the ability to confer a preferred direction of motion.

Periodic simple cells in cat area 17

1984 ◽  
Vol 52 (2) ◽  
pp. 372-387 ◽  
Author(s):  
W. H. Mullikin ◽  
J. P. Jones ◽  
L. A. Palmer
Keyword(s):  
Receptive Field ◽  
Spatial Frequency ◽  
Frequency Domain ◽  
Time Course ◽  
Receptive Fields ◽  
Area 17 ◽  
Simple Cells ◽  
Primary Zone ◽  
Spatially Distributed ◽  
Spatial Frequency Domain

Quantitative, high-resolution static receptive-field plots (response planes) in cat area 17 revealed simple cells whose receptive fields were composed of four to six excitatory regions alternating in space with up to seven inhibitory regions. The size, shape, and spacing of the excitatory regions within these receptive fields were highly regular, giving the receptive field a periodic appearance in space. We call these periodic simple cells. A periodic simple cell's response to moving stimuli could, in general, be anticipated from the detailed spatiotemporal map of excitatory and inhibitory regions provided by response planes. This observation suggests that periodic simple cells, like the more common simple cells composed of one to three excitatory regions, sum spatially distributed inputs in a roughly linear manner. Based on a quantitative assessment of the spatial distribution and time course of response of single excitatory regions within periodic receptive fields, as described in the previous paper, we characterized periodic simple cells as either X-like or Y-like. Furthermore, we found that periodic simple cells classified as X-like gave a more sustained response to standing contrast and had significantly smaller excitatory regions than those cells classified as Y-like. Periodic simple cells were found in layer III and at the border between layers III and IVab. It is suggested that these cells, which reside outside the primary zone of geniculate termination and include both X-like and Y-like types, may be constructed hierarchically from the convergence of lower order simple cells. In the spatial-frequency domain, periodic simple receptive fields were predicted to have bandwidths at half-maximum ranging from 0.80 to 1.4 octaves. By comparison, the predicted bandwidths of cells composed of two or three excitatory regions ranged from 1.6 to 4.3 octaves. Thus as additional excitatory regions are added to the receptive fields of simple cells, their bandwidth narrows in the spatial-frequency domain.

Ferrier lecture - Functional architecture of macaque monkey visual cortex

1977 ◽  
Vol 198 (1130) ◽  
pp. 1-59 ◽  
Keyword(s):  
Visual Cortex ◽  
Visual Field ◽  
Receptive Field ◽  
Striate Cortex ◽  
Single Cells ◽  
Ocular Dominance ◽  
Receptive Fields ◽  
Macaque Monkey ◽  
Area 17 ◽  
Orientation Specificity

Of the many possible functions of the macaque monkey primary visual cortex (striate cortex, area 17) two are now fairly well understood. First, the incoming information from the lateral geniculate bodies is rearranged so that most cells in the striate cortex respond to specifically oriented line segments, and, second, information originating from the two eyes converges upon single cells. The rearrangement and convergence do not take place immediately, however: in layer IVc, where the bulk of the afferents terminate, virtually all cells have fields with circular symmetry and are strictly monocular, driven from the left eye or from the right, but not both; at subsequent stages, in layers above and below IVc, most cells show orientation specificity, and about half are binocular. In a binocular cell the receptive fields in the two eyes are on corresponding regions in the two retinas and are identical in structure, but one eye is usually more effective than the other in influencing the cell; all shades of ocular dominance are seen. These two functions are strongly reflected in the architecture of the cortex, in that cells with common physiological properties are grouped together in vertically organized systems of columns. In an ocular dominance column all cells respond preferentially to the same eye. By four independent anatomical methods it has been shown that these columns have the form of vertically disposed alternating left-eye and right-eye slabs, which in horizontal section form alternating stripes about 400 μm thick, with occasional bifurcations and blind endings. Cells of like orientation specificity are known from physiological recordings to be similarly grouped in much narrower vertical sheeet-like aggregations, stacked in orderly sequences so that on traversing the cortex tangentially one normally encounters a succession of small shifts in orientation, clockwise or counterclockwise; a 1 mm traverse is usually accompanied by one or several full rotations through 180°, broken at times by reversals in direction of rotation and occasionally by large abrupt shifts. A full complement of columns, of either type, left-plus-right eye or a complete 180° sequence, is termed a hypercolumn. Columns (and hence hypercolumns) have roughly the same width throughout the binocular part of the cortex. The two independent systems of hypercolumns are engrafted upon the well known topographic representation of the visual field. The receptive fields mapped in a vertical penetration through cortex show a scatter in position roughly equal to the average size of the fields themselves, and the area thus covered, the aggregate receptive field, increases with distance from the fovea. A parallel increase is seen in reciprocal magnification (the number of degrees of visual field corresponding to 1 mm of cortex). Over most or all of the striate cortex a movement of 1-2 mm, traversing several hypercolumns, is accompanied by a movement through the visual field about equal in size to the local aggregate receptive field. Thus any 1-2 mm block of cortex contains roughly the machinery needed to subserve an aggregate receptive field. In the cortex the fall-off in detail with which the visual field is analysed, as one moves out from the foveal area, is accompanied not by a reduction in thickness of layers, as is found in the retina, but by a reduction in the area of cortex (and hence the number of columnar units) devoted to a given amount of visual field: unlike the retina, the striate cortex is virtually uniform morphologically but varies in magnification. In most respects the above description fits the newborn monkey just as well as the adult, suggesting that area 17 is largely genetically programmed. The ocular dominance columns, however, are not fully developed at birth, since the geniculate terminals belonging to one eye occupy layer IVc throughout its length, segregating out into separate columns only after about the first 6 weeks, whether or not the animal has visual experience. If one eye is sutured closed during this early period the columns belonging to that eye become shrunken and their companions correspondingly expanded. This would seem to be at least in part the result of interference with normal maturation, though sprouting and retraction of axon terminals are not excluded.

Neuronal Activity in Somatosensory Cortex of Monkeys Using a Precision Grip. I. Receptive Fields and Discharge Patterns

1999 ◽  
Vol 81 (2) ◽  
pp. 825-834 ◽  
Author(s):  
Iran Salimi ◽  
Thomas Brochier ◽  
Allan M. Smith
Keyword(s):  
Receptive Field ◽  
Somatosensory Cortex ◽  
Neuronal Activity ◽  
Single Cells ◽  
Precision Grip ◽  
Receptive Fields ◽  
Pressure Change ◽  
Discharge Pattern ◽  
Cortical Cells ◽  
Discharge Patterns

Neuronal activity in somatosensory cortex of monkeys using a precision grip. I. Receptive fields and discharge patterns. Three adolescent Macaca fascicularis monkeys weighing between 3.5 and 4 kg were trained to use a precision grip to grasp a metal tab mounted on a low friction vertical track and to lift and hold it in a 12- to 25-mm position window for 1 s. The surface texture of the metal tab in contact with the fingers and the weight of the object could be varied. The activity of 386 single cells with cutaneous receptive fields contacting the metal tab were recorded in Brodmann’s areas 3b, 1, 2, 5, and 7 of the somatosensory cortex. In this first of a series of papers, we describe three types of discharge pattern, the receptive-field properties, and the anatomic distribution of the neurons. The majority of the receptive fields were cutaneous and covered less than one digit, and a χ2 test did not reveal any significant differences in the Brodmann’s areas representing the thumb and index finger. Two broad categories of discharge pattern cells were identified. The first category, dynamic cells, showed a brief increase in activity beginning near grip onset, which quickly subsided despite continued pressure applied to the receptive field. Some of the dynamic neurons responded to both skin indentation and release. The second category, static cells, had higher activity during the stationary holding phase of the task. These static neurons demonstrated varying degrees of sensitivity to rates of pressure change on the skin. The percentage of dynamic versus static cells was about equal for areas 3b, 2, 5, and 7. Only area 1 had a higher proportion of dynamic cells (76%). A third category was identified that contained cells with significant pregrip activity and included cortical cells with both dynamic or static discharge patterns. Cells in this category showed activity increases before movement in the absence of receptive-field stimulation, suggesting that, in addition to peripheral cutaneous input, these cells also receive strong excitation from movement-related regions of the brain.

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.

scholarly journals Spatial and Temporal Features of Synaptic to Discharge Receptive Field Transformation in Cat Area 17

2010 ◽  
Vol 103 (2) ◽  
pp. 677-697 ◽  
Author(s):  
Lionel G. Nowak ◽  
Maria V. Sanchez-Vives ◽  
David A. McCormick
Keyword(s):  
Spatial Frequency ◽  
Response Latency ◽  
Frequency Tuning ◽  
Receptive Fields ◽  
Width Ratio ◽  
Area 17 ◽  
Simple Cells ◽  
Complex Cells ◽  
Temporal Features ◽  
Simple And Complex Cells

The aim of the present study was to characterize the spatial and temporal features of synaptic and discharge receptive fields (RFs), and to quantify their relationships, in cat area 17. For this purpose, neurons were recorded intracellularly while high-frequency flashing bars were used to generate RFs maps for synaptic and spiking responses. Comparison of the maps shows that some features of the discharge RFs depended strongly on those of the synaptic RFs, whereas others were less dependent. Spiking RF duration depended poorly and spiking RF amplitude depended moderately on those of the underlying synaptic RFs. At the other extreme, the optimal spatial frequency and phase of the discharge RFs in simple cells were almost entirely inherited from those of the synaptic RFs. Subfield width, in both simple and complex cells, was less for spiking responses compared with synaptic responses, but synaptic to discharge width ratio was relatively variable from cell to cell. When considering the whole RF of simple cells, additional variability in width ratio resulted from the presence of additional synaptic subfields that remained subthreshold. Due to these additional, subthreshold subfields, spatial frequency tuning predicted from synaptic RFs appears sharper than that predicted from spiking RFs. Excitatory subfield overlap in spiking RFs was well predicted by subfield overlap at the synaptic level. When examined in different regions of the RF, latencies appeared to be quite variable, but this variability showed negligible dependence on distance from the RF center. Nevertheless, spiking response latency faithfully reflected synaptic response latency.

Sign in / Sign up

Export Citation Format

Share Document