Computation of color and brightness differences by neurons in the lateral geniculate nucleus of the rabbit
The responses of 51 neurons in the lateral geniculate nucleus of the rabbit to substitution of colored stimuli different brightness and stimuli differing only in intensity were studied. Neurons in the geniculate nucleus, like neurons in the visual cortex, were found to respond with initial phasic discharges at 50–90 msec after stimulus substitution, the magnitudes of these responses correlating with the interstimulus differences; neurons also showed prolonged tonic responses in which the spike frequency depended on the intensity of the stimulus presented. Analysis of phasic responses allowed two groups of neurons to be identified: some were specialized to discriminate stimulus intensity only, while others were specialized to discriminate both the intensity and the color tone of the stimulus. Use of the magnitude of the early phasic discharge as a measure of the difference between stimuli yielded a sensory space for lateral geniculate nucleus neurons. The responses of neurons in the first group (44 cells, 86%) produced a two-dimensional achromatic space with two axes-brightness and darkness; this structure appeared independently of whether stimuli were of the same or different color tones. The phasic responses of neurons in the second group (seven of 51, 14%) generated a four-dimensional space with two color and two achromatic axes. The color and achromatic spaces of lateral geniculate nucleus neurons were analogous to the spaces previously identified for neurons in the rabbit visual cortex using the same stimulation conditions. The sensory spaces reconstructed on the basis of neuron phasic discharges essentially coincided with the spaces obtained from analysis of the N85 component of visual evoked potentials in rabbits, which provides support for the vector information coding principle in the visual analyzer. The tonic discharges of most lateral geniculate nucleus neurons correlated linearly with changes in stimulus intensity and can be regarded as reflecting a pre-detector function for the visual cortex detector neurons.
Key wordsvector coding geniculate nucleus neurons four-dimensional color space achromatic space tonic discharge pre-detectors
Unable to display preview. Download preview PDF.
- 1.A. V. Vartanov, V. B. Polyanskii, E. N. Sokolov, and D. V. Evtikhin, “Characteristics of the color perceptual space of protanomals,” Zh. Vyssh. Nerv. Deyat., 48, No. 5, 788–796 (1998).Google Scholar
- 2.A. V. Latanov, A. Yu. Leonova, D. V. Evtikhin, and E. N. Sokolov, “Comparative neurobiology of color vision in humans and animals,” Zh. Vyssh. Nerv. Deyat., 47, No. 2, 308–320 (1997).Google Scholar
- 3.V. B. Polyanskii, D. V. Evtikhin, and E. N. Sokolov, “Brightness components of evoked potentials to color stimuli in rabbits,” Zh. Vyssh. Nerv. Deyat., 49, No. 6, 1046–1051 (1999).Google Scholar
- 4.V. B. Polyanskii, D. V. Evtikhin, and E. N. Sokolov, “Reconstruction of the brightness and color perceptual space in rabbits on the basis of visual potentials and comparison with data from behavioral experiments,” Zh. Vyssh. Nerv. Deyat., 50, No. 5, 843–854 (2000).Google Scholar
- 5.V. B. Polyanskii, D. V. Evtikhin, and E. N. Sokolov, “Calculation of color and brightness differences by human visual cortex neurons,” Zh. Vyssh. Nerv. Deyat., 55, No. 1, 60–70 (2005).Google Scholar
- 6.V. B. Polyanskii, G. L. Ruderman, V. V. Gavrilova, E. N. Sokolov, and A. V. Latanov, “Discrimination of light intensity by rabbits and the structure of its achromatic space,” Zh. Vyssh. Nerv. Deyat., 45, No. 5, 957–963 (1995).Google Scholar
- 7.V. B. Polyanskii,, E. N. Sokolov, T. Yu. Marchenko, D. V. Evtikhin, and G. L. Ruderman, “The perceptual color space of rabbits,” Zh. Vyssh. Nerv. Deyat., 48, No. 3, 496–504 (1998).Google Scholar
- 8.E. N. Sokolov, Perception and Conditioned Reflexes, A New View [in Russian], UMK Psikhologiya, Moscow (2003).Google Scholar
- 9.E. N. Sokolov and Ch. A. Izmailov, Color Vision, [in Russian], Moscow State University Press, Moscow (1984).Google Scholar
- 10.S. V. Fomin, E. N. Sokolov, and G. G. Vaitkyavichus, Artificial Sensory Organs. Questions in the Modeling of Sensory Systems [in Russian], Nauka, Moscow (1979).Google Scholar
- 11.G. H. Jacobs, “The distribution and nature of color vision among the mammals,” Biol. Camb. Philos. Soc., 68, No. 3, 413–471 (1993).Google Scholar