High-resolution spatio-temporal mapping of visual pathways using multi-electrode arrays

The parallel processing of visual information was studied with penetrating microelectrode arrays. We studied the high-resolution visuotopic organizati on of cat primary visual cortex, and the encoding of simple visual stimuli by ensembles of ganglion cells in the isolated turtle retina. The high-reso lution visuotopic organization of visual cortex is non-conformal. Regions o f visual cortex separated by 400 mu may have receptive field centers that a re separated by as much as 3 degrees, or they may superimpose. Ganglion cel ls are 'generalists', and are poor specifiers of the color of full field vi sual stimuli. Groups of 'luminosity' type ganglion cells can assist in the specification of stimulus color, but even individual 'chromatic' ganglion c ells are not capable of quality color specification. These basic studies ha ve relevance to the development of visual neuroprostheses based upon electr ical stimulation of the retina and cortex. (C) 2001 Elsevier Science Ltd. A ll rights reserved.