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Laboratory of Biophysics

Bruce W. Knight

Our laboratory's central effort is toward understanding how the nervous system processes input information, in terms of the broad multicellular interactions among biophysical processes which individually lie at the subcellular level. This effort demands the conjoined development of theoretical tools such as dynamical equations and computer simulation, and of experimental procedures that induce and record detailed neural responses which our theoretical tools may then describe quantitatively. Because the visual sense provides unique opportunities for highly structured input, our efforts focus on the visual part of the central nervous system, particularly that of humans and those of other vertebrates whose visual systems share key features of evolutionary kinship with humans.

Patterns of colored light in motion arriving from the external visual world induce dynamical patterns of electrical activity in a sequence of neural processing networks that start with the retina (which is specialized brain tissue) and continue into the brain. At each step, profound signal transformations occur, which ultimately reduce the input to a form useful for action. We study that process with computer-generated stimuli which are designed by theoretical considerations that facilitate the interpretation of response features in terms of the responding system's predictive dynamical laws. Our data include single-cell recordings from identified nerve cells of anesthetized animals, overall stimulus-evoked potentials in experimental animals and in humans, and direct quantitative reports by human observers.

Our recent emphasis has been upon retina, primary visual cortex, and the lateral geniculate nucleus, which is a processing network between retina and cortex. Our laboratory has been one of the principal contributors to the currently emerging understanding of the dynamics of the cat retina, which shows numerous dynamical features that prove typical of many vertebrates. Our recent results with primate retina (monkey, human) reveal not only catlike cells, but a major additional interacting population with novel dynamical properties.