CORTICOTHALAMIC CONNECTIONS OF AUDITORY-RELATED AREAS OF THE TEMPORAL-LOBE IN THE RHESUS-MONKEY

Corticothalamic connections of auditory areas of the superior temporal regions (STR) were investigated in the rhesus monkey. These connectio ns are organized according to the recently described architectonic par cellation of the STR. The core line regions of the supratemporal plane (STP) project to the medial geniculate nucleus (MGN). All regions exc ept the primary auditory area also have projections to additional thal amic nuclei. The rostral STP has strong connections with the caudal pa rt of the ventral subdivision (MGv) of MGN as well as with medial pulv inar (PM). In contrast the primary auditory area projects mainly to ro stral MGv. The caudalmost STP projects mainly to the dorsal subdivisio n (MGd) and to the magnocellular subdivision (MGmc) as well as to the PM and the lateral (PL) and oral (PO) pulvinar, nucleus limitans (Li), and mediodorsal (MD) nucleus. The belt line regions of the superior t emporal gyrus (STG) project mainly to the pulvinar but also have proje ctions to MGd and MGmc. Specifically, rostral STG projects to the caud al part of PM, to MGmc, and to the suprageniculate (SG) nucleus, where as caudal STG projects to the rostral part of PM and to FL, PO, MGd, M Gmc, SG-Li and MD nuclei. The root line areas in the circular sulcus o f the Sylvian fissure project mainly to MGmc but also to MGd, PM, and SG-Li nuclei. These connections originate mainly from neurons in corti cal layer VI, with some from layer Vb. It is suggested that these conn ections may be involved in different aspects of auditory information p rocessing. (C) 1994 Wiley-Liss, Inc.