Spatial frequency characteristics of brisk and sluggish ganglion cells of the cat's retina (original) (raw)

Spatiotemporal frequency responses of cat retinal ganglion cells

The Journal of General Physiology, 1987

Spatiotemporal frequency responses were measured at different levels of light adaptation for cat X and Y retinal ganglion cells. Stationary sinusoidal luminance gratings whose contrast was modulated sinusoidally in time or drifting gratings were used as stimuli . Under photopic illumination, when the spatial frequency was held constant at or above its optimum value, an X cell's responsivity was essentially constant as the temporal frequency was changed from 1 .5 to 30 Hz. At lower temporal frequencies, responsivity rolled off gradually, and at higher ones it rolled off rapidly. In contrast, when the spatial frequency was held constant at a low value, an X cell's responsivity increased continuously with temporal frequency from a very low value at 0.1 Hz to substantial values at temporal frequencies higher than 30 Hz, from which responsivity rolled off again . Thus, 0 cycles -deg' became the optimal spatial frequency above 30 Hz. For Y cells under photopic illumination, the spatiotemporal interaction was even more complex. When the spatial frequency was held constant at or above its optimal value, the temporal frequency range over which responsivity was constant was shorter than that of X cells . At lower spatial frequencies, this range was not appreciably different . As for X cells, 0 cycles deg ' was the optimal spatial frequency above 30 Hz . Temporal resolution (defined as the high temporal frequency at which responsivity had fallen to 10 impulses -s') for a uniform field was^-95 Hz for X cells and^-120 Hz for Y cells under photopic illumination . Temporal resolution was lower at lower adaptation levels. The results were interpreted in terms of a Gaussian centersurround model . For X cells, the surround and center strengths were nearly equal at low and moderate temporal frequencies, but the surround strength exceeded the center strength above 30 Hz . Thus, the response to a spatially uniform stimulus at high temporal frequencies was dominated by the surround. In addition, at temporal frequencies above 30 Hz, the center radius increased .

Bimodal receptive fields of cat retinal ganglion cells

Vision research, 1983

Receptive fields of cat retinal ganglion cells were stimulated by a drifting, sinusoidal luminance pattern of fixed contrast. The amplitudes and phases of the harmonic components in the response were determined as a function of spatial frequency. For most cells, the graphs of response vs spatial frequency (when plotted on linear scales) were unimodal and skewed towards zero frequency for all stimulus orientations. However, some cells had bimodal frequency response functions when the stimulus was in the non-preferred orientation. These unusual cells also exhibited a sudden phase-reversal of pi radians which occurred at the frequency of the changeover between the two modes. Calculations based on the experimental data predicted two distinctly separate regions of high sensitivity within the receptive centres of such cells. A narrow bar stimulus was used to confirm that the receptive fields had, in effect, double centres.

Receptive field mechanisms of cat X and Y retinal ganglion cells

The Journal of General Physiology, 1979

A B S T R A C: T We investigated receptive field properties of cat retinal ganglion cells with visual stimuli which were sinusoidal spatial gratings amplitude modulated in time by a sum of sinusoids. Neural responses were analyzed into the Fourier components at the input frequencies and the components at sum and difference frequencies. The first-order frequency response of X cells had a marked spatial phase and spatial frequency dependence which could be explained in terms of linear interactions between center and surround mechanisms in the receptive field. The second-order frequency response of X cells was much smaller than the first-order frequency response at all spatial frequencies. The spatial phase and spatial frequency dependence of the first-order frequency response in Y cells in some ways resembled that of X cells. However, the Y firstorder response declined to zero at a much lower spatial frequency than in X cells. Furthermore, the second-order frequency response was larger in Y cells; the second-order frequency components became the dominant part of the response for patterns of high spatial frequency. This implies that the receptive field center and surround mechanisms are physiologically quite different in Y cells from those in X cells, and that the Y cells also receive excitatory drive from an additional nonlinear receptive field mechanism.

Size, scatter and coverage of ganglion cell receptive field centres in the cat retina

The Journal of Physiology, 1979

1. Receptive field centre sizes of brisk-sustained (X) and brisk-transient (Y) ganglion cells of the cat retina were assessed by three different methods: small spot mapping, area threshold method and spatial resolution. 2. Centre sizes of brisk-sustained (X) cells increased from 20' in the central area to about 70' at an eccentricity of 4-5 mm, centre sizes of brisk-transient (Y) cells from 50' in the central area to about 140' at 5 mm eccentricity. 3. The scatter of centre sizes at one retinal location was measured by recording as many ganglion cells as possible in one cat in a small field of retina. The centre sizes of the individual classes were homogeneous and exhibited only a small amount of scatter. 4. The coverage of the retina by the different ganglion cell classes was assessed from their density and their receptive field centre area. At every retinal location the receptive field centres of seven to twenty brisk-sustained (X) cells and of three to six brisk-transient (Y) cells were found to overlap. Sluggish concentric and non-concentric cells taken together have a coverage factor of about 60.

Linear and nonlinear spatial subunits in Y cat retinal ganglion cells

The Journal of physiology, 1976

1. The mechanism which makes Y cells different from X cells was investigated. 2. Spatial frequency contrast sensitivity functions for the fundamental and second harmonic responses of Y cells to alternating phase gratings were determined. 3. The fundamental spatial frequency response was predicted by the Fourier transform of the sensitivity profile of the Y cell. The high spatial frequency cut-off of a Y cell's fundamental response was in this way related to the centre of the cell's receptive field. 4. The second harmonic response of a Y cell did not cut off at such a low spatial frequency as the fundamental response. This result indicated that the source of the second harmonic was a spatial subunit of the receptive field smaller in spatial extent than the centre. 5. Contrast sensitivity vs. spatial phase for a Y cell was measured under three conditions: a full grating, a grating seen through a centrally located window, a grating partially obscured by a visual shutter. The 2n...

A spatial analysis of on- and off-ganglion cells in the cat retina

Vision Research, 1983

Using reduced silver staining methods it was possible to stain all d-ganglion cells of the cat retina. The dendritic trees of a-cells are unistratified in either of two laminae within the inner plexiform layer. This stratification difference was shown physiologically to correspond to the on-off dichotomy. For all a-cells recorded, the dendritic field was covered by the corresponding receptive field centre. In addition the general shape of the receptive fieId centre corresponded to the shape of the dendritic field. The size of the dendritic tree was always smaller than the receptive field centre. The topo~aphi~al dist~bution of on-and 0%ol cells could be studied. They were found to occur in about equal numbers. Both on-and off-a-cell perikarya form a regular lattice and both lattices are superimposed independently. The dendritic branches of neighbouring a-cells overlap and each retinal point is covered by the dendritic field of at least one on-and one off-cl-cell. After horseradish peroxidase (HRP) injection into the lateral geniculate nucleus all p-cells were labelled. In this way it is shown that about 55% of all ganglion cells are /I-cells. The mosaic of on-and off-S-cells was studied from the HRP-labelled material. It is commonly assumed that beta-cells are associated with the resolution of fine detail in the cat visual system. The mosaic of @ells imposes some constraints and permits some predictions to be made with respect to the cat's visual discrimination. Retina Ganglion cells Receptive field On-off cells *M.R.C. Cell Biophysics Unit, King's College, 26-29 Drury Lane. London WCZB SRL, England.

The receptive field of the primate P retinal ganglion cell, I: Linear dynamics

Visual Neuroscience, 1997

The ganglion cells of the primate retina include two major anatomical and functional classes: P cells which project to the four parvocellular layers of the lateral geniculate nucleus (LGN), and M cells which project to the two magnocellular layers. The characteristics of the P-cell receptive field are central to understanding early form and color vision processing . In this and in the following paper, P-cell dynamics are systematically analyzed in terms of linear and nonlinear response properties. Stimuli that favor either the center or the surround of the receptive field were produced on a CRT and modulated with a broadband signal composed of multiple m-sequences (Benardete et al., 1992ft;. The first-order responses were calculated and analyzed in this paper (part I). The findings are: (1) The first-order responses of the center and surround depend linearly on contrast.

Spatial Asymmetry in Cat Retinal Ganglion Cell Responses

Enroth-Cugell and proposed a classification of retinal ganglion cells into X cells, which exhibit approximate linear spatial summation and largely sustained responses, and Y cells, which exhibit nonlinearities and transient responses. has suggested that the dominant characteristics of both X and Y cells can be simulated with a single model simply by changing receptive field profiles to match those of the anatomical counterparts of X and Y cells. He also proposed that a significant component of the spatial nonlinearities observed in Y (and sometimes X) cells can result from photoreceptor nonlinearities coupled with push-pull bipolar connections. Specifically, an asymmetry was predicted in the ganglion cell response to rectangular gratings presented at different locations in the receptive field under two conditions: introduction/withdrawal (on-off), or contrast reversal. When measuring the response to these patterns as a function of spatial phase, the standard difference-of-Gaussians model predicts symmetrical responses about the receptive field center, while the push-pull model predicts slight but significant asymmetry in the on-off case only. To test this hypothesis, we have recorded ganglion cell responses from the optic tract fibers of anesthetized cat. The mean and standard deviations of responses to on-off and contrast-reversed patterns were compared. We found that all but one of the cells that yielded statistically significant data confirmed the hypothesis. These results largely support the theoretical prediction.

How the contrast gain control modifies the frequency responses of cat retinal ganglion cells

The Journal of physiology, 1981

1. A model is proposed for the effect of contrast on the first-order frequency responses of cat retinal ganglion cells. The model consists of several cascaded low pass filters ('leaky integrators') followed by a single stage of negative feed-back. 2. Values of time constants and gain of the components in this model were chosen to approximate (with least-squared deviation) experimentally measured first-order frequency responses. In the experiments used for the analysis, the visual stimulus was a sine grating modulated by a sum of sinusoids. 3. For both X cells and Y cells, the over-all gain and the time constants of the cascade of low pass filters were insensitive to contrast. 4. In all cells, the gain-bandwidth product of the negative feed-back loop was markedly increased with increasing contrast. 5. The effect of stimulation in the periphery of the receptive fields on the first-order frequency response to a centrally placed spot was identical to the effect of increasing con...