Bilateral projections from the visual cortex to the striatum in the cat.

Direct projections from visual areas 17, 18, 19, and lateral suprasylvian visual area (LS) to the striatum were searched for in 12 adult cats using the autoradiographic technique to detect neuronal pathways. Striatal labels were found only after injections in areas 19 and LS. Projections homolateral to the injection sites were observed from both areas to the head and body of the caudate nucleus and to the putamen. Contralateral projections were found from both areas 19 and LS: however, area 19 did not project to the contralateral putamen. The extent of contralateral projections was smaller and they were confined within the same regions as the homolateral ones. Silver grains were often arranged in cluster-like patches, which were more evident ipsilaterally, in the head of the caudate nucleus and after injections in area LS. The present data support the view of a not strictly topographical segregation of striatal projections from the cat visual cortex.