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 corticostr iate projections from over a dozen higher visual cortical areas [visual-rec ipient sector; Updyke, B.V. (1993) J. Comp. Neurol., 327, 159-193.]. Like t heir cortical counterparts, the thalamostriate projections to the caudate d istribute in a patchy manner that suggests potential overlap or intermingli ng spatial relationships between the two major afferents. All of the visual ly related thalamic nuclei projecting to the striatum receive ascending sig nals from the superior colliculus, suggesting that the constraints placed u pon tectal processing by striatonigral control have important consequences for central perceptuomotor processing at the striatal and cortical levels.