Somatomotor functioning in marmosets and the evolution of spinal cords in primates

Abstract

Frontoparietal cortex, consisting of motor and early somatosensory areas, is the first cortical region to receive inputs from the spinal cord and the last to convey outputs to the spinal cord. This dissertation investigated the functioning of frontoparietal cortex and the spinal cord in three parts. First, the organization of motor cortex in marmosets, which has not previously been examined, was investigated. The physiologic and architectonic results suggest that marmoset motor cortex is organized similarly to that of other primates. Second, the organization of somatosensory cortex after a lesion of the dorsal columns of the spinal cord was investigated in marmosets. The physiologic, behavioral, and architectonic results suggest that marmoset somatosensory cortex is capable of cortical plasticity similar to that of other New World Primates, and that the behavioral deficit and the extent of cortical reorganization may be linked. Third, the cellular composition of the spinal cord was compared across several primate species and suggests that in larger brains, disproportionately more neurons are added to the cortex and cerebellum than to the rest of the brain or the spinal cord.