Cytology of human dorsal midcingulate and supplementary motor cortices

Human dorsal midcingulate cortex (MCC) is activated during many cognitive tasks and its role in skeletomotor functions is reflected in the size, density, and neurofilament proteins (NFP) expressed by neurons in this region. The present study used antibodies for neuron-specific nuclear binding protein and NFP in three postmortem cases to assess the cytology of the dorsal midcingulate areas 24c′, 24d, and 32′ and supplementary motor cortex. Area 24c′ has a thin layer Va and a Vb with large and NFP+ neurons not present on the gyral surface. Area 24d has two divisions; area 24dv on the ventral bank has layer Vb neurons that form aggregates, while area 24dd on the dorsal bank has large and solitary layer Vb pyramids. Co-registration of each case to standardized coordinates showed that the rostral area 24d border is at the vertical plane of the anterior commissure and its caudal border with area 23c is −2±0.21 cm in the y-axis. The transition to supplementary motor areas is characterized by significant increases in the density of large, NFP expressing neurons in layer IIIc and a substantial reduction in the size and density of such neurons in layer V. Since many acute pain studies activate dorsal MCC, understanding the architecture of this region will help explain its selective vulnerability to chronic pain and stress syndromes.