Thalamic afferents to the anterior and middle suprasylvian gyri in the cat traced with horseradish peroxidase.

The anatomical organization of thalamic projections to the anterior and middle suprasylvian gyri in the cat has been studied by retrograde axonal transport of horseradish peroxidase. Area 5 receives a large number of fibers from the posterior lateral nucleus, and a few fibers from the dorsal lateral nucleus. It receives many fibers from the ventrolateral part of the medial pulvinar nucleus and from the suprageniculate and lateral pulvinar nuclei. Area 5 receives a considerable number of fibers from the lateral central, anterior ventral and lateral ventral nuclei, and only a few fibers from the paracentral nucleus. Area 7 receives numerous fibers from the medial pulvinar (dorsolateral and ventrolateral parts), lateral pulvinar, dorsal lateral, posterior lateral, lateral central and anterior ventral nuclei, and a lesser number from the lateral ventral nucleus. The suprageniculate and paracentral nuclei project only a few fibers to area 7. Area 21 has its main input from the medial pulvinar nucleus, mainly its dorsolateral part. It receives many fibers from the lateral pulvinar nucleus, and a few fibers from the dorsal lateral nuclei, the dorsolateral part of the posterior lateral nucleus and the lateral central and paracentral nucleus. Area 21 receives very few fibers from the dorsal lateral geniculate nucleus (NIM) and the inferior pulvinar nucleus, but receives no fibers from the anterior and lateral ventral nuclei. The thalamic afferents from the lateral bank of the lateral sulcus are similar to those from area 7 (crown). However, the lateral bank receives more fibers from the posterior lateral nucleus, and lesser fibers from the paracentral, anterior ventral and lateral ventral nuclei. It receives scarcely any fibers from the suprageniculate nucleus. The medial bank of the middle suprasylvian sulcus (Clare-Bishop area) receives cortical afferents mainly from the inferior pulvinar nucleus. It also receives fibers from the medial pulvinar nucleus, and a lesser number from the lateral pulvinar and posterior lateral nuclei. It receives a few fibers from the dorsal lateral geniculate nucleus, particularly NIM and lamina B, and very few fibers from the suprageniculate, lateral central and paracentral nuclei.