A Laboratory for Neural Computation Publication

Nature Neuroscience, 3(1):54-63, January 2000.

A model for intradendritic computation of binocular disparity.

Kevin A. Archie, Neuroscience Program, USC
Bartlett W. Mel , Biomedical Engineering Department, USC

ABSTRACT

Many complex cells in the primary visual cortex of cat and monkey are finely tuned to binocular disparity. The prevailing model holds that each disparity-tuned complex cell is driven by several orientation-tuned binocular simple cells. In cat, however, some complex cells receive direct LGN input, and in macaque, binocular simple cells are rare. Using a biophysically detailed compartmental model, we show that active dendrites of a single pyramidal neuron can perform the multiple simple-cell-like subunit computations that simultaneously underlie both orientation and disparity tuning, producing complex-cell-like responses remarkably similar to data from cat and monkey. We also show that the responses produced by our biophysically-detailed compartmental model can be predicted by a simple algebraic formula closely related to existing ``energy'' models. Finally, we show that excitatory and inhibitory synapses together yield a stronger subunit nonlinearity and more realistic tuning curves than excitation alone. We conclude that active dendrites could contribute to disparity tuning in complex cells, and we outline experiments to test the predictions of our model.

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