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Mechanoreceptor representation and topography of Brodmann's areas 3 and 1 of Macaca mulatta

Abstract:

The classical surface evoked potential studies of Marshall, Woolsey, and Bard (1937) and Adrian (1941) in Macaca mulatta, and the human stimulation studies of Penfield and Boldrey (1937), and Penfield and Rasmussen (1950) have led to the concept that the body surface is represented singly in the somatosensory cortex of the postcentral gyrus. This representation crosses at least three distinct cytoarchitectonic divisions. Although this cytoarchitectonic parcellation of the postcentral gyrus has been known for many years, it was not until 1959 that Powell and Mountcastle (1959a, b) first demonstrated functional specialization of these divisions. These investigators demonstrated a segregation of deep and cutaneous mechanoreceptor input in the postcentral gyrus which they defined as submodalities of sensation. The deep receptor input projected to the more posterior areas of the postcentral gyrus, and the cutaneous to the more rostral areas. Although the primary purpose of their experiments was not cortical mapping, they noted that cortical cells were encountered in the different cytoarchitectonic divisions that could be driven by stimulation of a similar peripheral receptive field of the apical portions of the body. These findings, they observed, did not appear compatible with the accepted view of a single body representation in the postcentral gyrus, the proximal and dorsal portions represented posteriorly and the apical and ventral portion anteriorly. In fact, Jones and Powell (1967, 1970) have predicted that the body topography may be represented more than once in the postcentral gyrus-possible once for each of the cytoarchitectonic divisions. This …