Color Sensitivity of Cells Responsive to Complex Stimuli in the Temporal Cortex (original) (raw)

Evidence that circuits for spatial and color vision segregate at the first retinal synapse

Neuron, 1999

This cell increased firing to long wavelengths restricted to a small center and was unaffected when the long University of Pennsylvania Medical School Philadelphia, Pennsylvania 19104 wavelengths extended into the surround. However, it decreased firing when middle wavelengths covered both center and surround. Complementary types were also found: centers tuned to middle wavelengths with Different psychophysical "channels" mediate our persurrounds tuned to long wavelengths, and centers tuned ception of fine spatial patterns and color. The spatial to short wavelengths with surrounds tuned to middle channel compares the photon catch between adjacent and long wavelengths. Similar response types were cones, regardless of type, and thus supports perception found for retinal ganglion cells (de Monasterio, 1978a, of patterns as fine as the cone mosaic (Williams, 1986). 1978b).

Dynamics of primate P retinal ganglion cells: responses to chromatic and achromatic stimuli

The Journal of Physiology, 1999

1. The majority of primate retinal ganglion cells (RGCs) project to the parvocellular layers of the lateral geniculate nucleus (LGN). These P cells play a central role in early visual processing. 2. An improved method of systems analysis has allowed us to explore the dynamics of the colour-opponent subregions of P-cell receptive fields with a single chromatic stimulus. The data show that the centre and surround subregions of the P-cell receptive field have similar temporal responses, but the surround is slightly delayed. The centre and surround demonstrate a large degree of chromatic selectivity. 3. The responses of the centre and surround subregions were fitted with a linear model and the model was used to predict the responses of P cells to new chromatic and achromatic stimuli. Although linear models predict the chromatic responses well, simple linear combinations of centre and surround responses fail to predict P_cell responses to achromatic stimuli. 4. The temporal responses of the different subpopulations of P cells, such as ONÏOFF or

The dynamics of primate M retinal ganglion cells

Visual Neuroscience, 1999

A knowledge of the dynamics (temporal properties) of neuronal populations is essential for an understanding of their function, and is also crucial when one attempts to develop computational or mathematical models of the neurons. Here we review the temporal properties of the receptive fields (RFs) of the two best-studied types of ganglion cells in the primate retina, those that project to the parvocellular (P) and magnocellular (M) layers of the dorsal lateral geniculate nucleus.

Temporal response of ganglion cells of the macaque retina to cone-specific modulation

Journal of the Optical Society of America A, 1995

The temporal response of cone inputs to macaque retinal ganglion cells were compared with cone-specific sinusoidal modulation used to isolate each cone type. For all cell types of the parvocellular (PC) pathway, temporal responsivity was similar for short (S)-, middle (M)-, and long (L)-wavelength-sensitive cone inputs, apart from small latency differences between inputs to center and surround. The temporal response resembled that expected from receptor physiology. Responses of cells of the magnocellular pathway to M-or L-cone modulation showed more complex properties indicative of postreceptoral processing. Human psychophysical temporal-sensitivity functions were acquired with S-cone modulation under conditions similar to those for the physiological measurements. Ratios of psychophysical to physiological data from S-cone cells (the only cells that respond to this stimulus) yielded an estimate of the central filter acting upon PC-pathway signals. The filter characteristic could be described by a four-stage low-pass filter with corner frequency 3 -5 Hz.

Luminance and chromatic modulation sensitivity of macaque ganglion cells and human observers

Journal of the Optical Society of America A, 1990

We measured the sensitivity of macaque ganglion cells to luminance and chromatic sinusoidal modulation. Phasic ganglion cells of the magnocellular pathway (M-pathway) were the more sensitive to luminance modulation, and tonic ganglion cells of the parvocellular pathway (P-pathway) were more sensitive to chromatic modulation. With decreasing retinal illuminance, phasic ganglion cells' temporal sensitivity to luminance modulation changed in a manner that paralleled psychophysical data. The same was true for tonic cells and chromatic modulation. Taken together, the data suggest strongly that the cells of the M-pathway form the physiological substrate for detection of luminance modulation and the cells of the P-pathway the substrate for detection of chromatic modulation. However, at high light levels, intrusion of a so-called luminance mechanism near 10 Hz in psychophysical detection of chromatic modulation is probably due to responses in the M-pathway, arising primarily from a nonlinearity of cone summation. Both phasic and tonic ganglion cells responded to frequencies higher than can be psychophysically detected. This suggests that central mechanisms, acting as low-pass filters, modify these cells' signals, though the corner frequency is lower for the P-pathway than for the M-pathway. For both cell types, the response phase at different frequencies was consistent with the cells' description as linear filters with a fixed time delay.

Temporal sensitivity of macaque ganglion cells to lights of different chromaticity

Color Research & Application, 2001

Three psychophysical paradigms have shown that moderately high retinal illuminance (ca. 1000 td) longwavelength chromatic adaptation results in a disproportionate reduction in visual sensitivity to rapidly modulated lights. (i) Critical-flicker-fusion-log retinal illuminance (CFF-log I) functions are shallower for long-wavelength than middle-wavelength modulated lights. (ii) A long-wavelength light modulated just above CFF appears as flickering if a steady middle-wavelength pedestal is added. (iii) The R/G ratio for heterochromatic modulation photometric (HMP) equality increases with light level when the mean chromaticity is Ϸ605 nm, but not when it is Ϸ570 nm. The goal was to evaluate whether Magnocellular-(MC-) pathway retinal ganglion cells show reduced modulation sensitivity with long-wavelength adaptation, as is observed with these three psychophysical paradigms. In Experiment (1), CFFs for 554 and 638 nm lights were estimated by noting the temporal frequencies at which the cells firing fell below 10 imp/s. CFF was measured for light levels between 1-1000 td. Seventeen of 17 units showed a higher CFF at 1000 td for 554 nm, consistent with psychophysical observation. In Experiment (2), a steady 1000 td 554 nm pedestal was added to a 1000 td 638 nm modulated light. Four of 6 units showed higher 638 nm CFF when the steady 554 nm pedestal was present. In Experiment (3), Heterochromatic Modulation Photometry responsivities were obtained at 200 and 2000 td as a function of the relative modulation of 554 and 638 nm counterphase lights. Chromaticity was metameric to either 605 or 570 nm. Fifteen of 17 units showed substantial changes in log (R/G) with luminance for the 605 nm, but not for the 570 nm adaptation condition. Thus, temporal phenomena observed psychophysically may be seen in MC-pathway cells. The results are interpretable as arising from interactions between signals originating from the Land M-cone receptor types, not from differences in temporal properties of the two-cone types.