Dual organization in the projections from the do sal lateral geniculate nucleus to the visual cortex in the cat

Abstract

Cortical projections of t h e dorsal lateral geniculate nucleus (LGNd) and several other related thalamic nuclei, posterior nucleus (PN) and posterior lateral nucleus (LP) of cats were studied using the Nauta impregnation method. LGNd is not a unitary structure but a complex of nuclei consisting of two major structural elements, main laminae (A, Al and B) and interlaminar nuclei (NIC and NIM). Main laminae project mainly to area 17, while interlaminar nuclei are linked primarily to area 18, and thus the geniculo-cortical system is organized in a dual manner. LGNd also projects to the banks of the middle and posterior suprasylvian sulci in a topographically organized manner. PN projects to both areas 18 and 19, and LP s ends fibers to the banks of the middle and posterior suprasylvian sulci. Thus, this region of cerebral cortex receives projections from both LGNd and LP. © 1973, Editorial Board of Okajimas Folia Anatomica Japonica. All rights reserved.