Striatal projections from the cat visual thalamus.

Anterograde transport methods reveal an extensive thalamostriate projection from the extrageniculate visual thalamus. These projections distribute to approximately the same regions of the striatum innervated by the corticostriate projections from over a dozen higher visual cortical areas [visual-recipient sector; Updyke, B.V. (1993) J. Comp. Neurol., 327, 159-193.]. Like their cortical counterparts, the thalamostriate projections to the caudate distribute in a patchy manner that suggests potential overlap or intermingling spatial relationships between the two major afferents. All of the visually related thalamic nuclei projecting to the striatum receive ascending signals from the superior colliculus, suggesting that the constraints placed upon tectal processing by striatonigral control have important consequences for central perceptuomotor processing at the striatal and cortical levels.