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Abstract

Research has shown that neurons in the visual pathways show an increasing configuration selectivity as one goes from V1 toward the temporal lobe, where cells may selectively respond to complex patterns, including images of faces or silhouettes. Yet elusive remains the process through which such neurons acquire their selectivity and whether such selectivity may change over periods of extensive training of animals in discrimination or recognition tasks. Similarly, it is unknown how training in motion discrimination tasks may induce alteration of response selectivity in neurons in motion processing areas. To study training induced changes in cortex we developed a method of chronically implanting bundles of 64 polyimide electrodes in monkeys, permitting recording from the same population of neurons for several months. Using such electrodes we recorded from temporal cortex for several months simultaneously from up to 10 isolated units from areas PGa and IPa. Recording from the same neurons was often possible for several days. In agreement with previous studies we found a large number of neurons with broad selectivity to various objects, including images of faces, birds, fruits, flowers, etc. The same electrodes were implanted in area MT for studying task-related neural changes. All implants are constructed by materials that permits the localization of electrodes in anatomical MR scans, as well as the BOLD concurrent imaging of the recorded areas in experiments using the same simulation conditions. We are currently comparing changes in the responsivity of neurons with those observed in the fMRI signal using identical stimulation conditions.