We examined the topographic organization of corticospinal neurons in the primary motor
cortex and in the two premotor areas on the lateral surface of the hemisphere [ie, the dorsal
premotor area (PMd) and the ventral premotor area (PMv)]. In two macaques, we labeled
corticospinal neurons that project beyond T7 or S2 by placing crystals of HRP into the
dorsolateral funiculus at these segmental levels. In another seven macaques, we labeled
corticospinal neurons that project to specific segmental levels of the spinal cord by injecting …

We examined the topographic organization of corticospinal neurons in the four premotor
areas on the medial wall of the hemisphere of macaques. These motor areas include the
supplementary motor area (SMA) and three areas buried within the cingulate sulcus: the
caudal cingulate motor area on the dorsal bank (CMAd), the caudal cingulate motor area on
the ventral bank (CMAv), and the rostral cingulate motor area (CMAr). In one set of animals,
we injected one fluorescent tracer into lower cervical segments of the spinal cord and …