Spatial distribution of cingulate cells projecting to the primary, supplementary, and pre-supplementary motor areas: a retrograde multiple labeling study in the macaque monkey

We examined the location and spatial distribution of cingulate cortical cel ls projecting to the forelimb areas of the primary motor cortex (MI). suppl ementary motor area (SMA), and pre-supplementary motor area (pre-SMA) using a multiple retrograde labeling technique in the monkeys (Macaca fuscata). The forelimb areas of the MI, SMA and pre-SMA were physiologically identifi ed, based on the findings of intracortical microstimulation (ICMS) and sing le cell recording. Three different tracers, diamidino yellow (DY), fast blu e (FB), and wheat germ agglutinin conjugated to horseradish peroxidase (WGA -HRP). were injected into each of the three motor areas in the same monkey. Retrogradely labeled cells in the cingulate cortex were plotted with an au tomated plotting system. Cells projecting to the forelimb area of the MI we re distributed in the two separate regions situated rostrocaudally in the d orsal and ventral banks of the cingulate sulcus, namely the rostral cingula te motor area (CMAr) and caudal cingulate motor area (CMAc). These two regi ons corresponded to the forelimb areas identified by the ICMS in the same a nimal. The distribution of projection cells to the SMA overlapped extensive ly with that of projection cells to the MI. Although the MI received relati vely sparse inputs from the CMAr than from the CMAc, the SMA received input s from the CMAr and its adjacent areas as much as from the CMAc. The projec tion cells to the pre-SMA were distributed in the anterior portion of the c ingulate cortex, including the anterior part of the CMAr and in a small par t of the cingulate gyrus. These findings indicate that the MI and SMA share a considerable common information from the cingulate cortex, including the CMAr and CMAc, whereas the pre-SMA receives a different set of information from the anterior part of the cingulate cortex. (C) 2001 Elsevier Science Ireland Ltd and the Japan Neuroscience Society. All rights reserved.