PROJECTION OF DORSAL ROOTS AND SENSORY NERVES TO CORTICAL SENSORY MOTOR REGIONS OF SQUIRREL MONKEY

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Abstract
[image] Potentials evoked by electrical stimulation of dorsal roots and nerves were mapped at the cerebral cortex of the squirrel monkey anesthetized with pentobarbital-sodium. The segmental organization in sensory area I (SmI and MsI) and the second sensory area (SmI I) were found to be generally consistent with the pattern reported previously in the squirrel monkey in a study which employed mechanical stimulation of cutaneous receptors. One exception to this general statement was the finding that the leg area was somewhat larger in this study. A complete somatotopically organized sensory representation was found in the supplementary motor area (MsII) on the medial wall and dorsal surface of the hemisphere rostral to MsI. The pattern and location of the sensory map matched closely the pattern and location of the motor map previously reported in this animal. Area for the arm and trunk representation were found on the medial wall of the hemisphere in what is referred to as Penfield''s supplementary sensory area. The results support the contention that there are at least 4 somatotopically organized sensory-motor areas and that there is a 6th sensory area at the cerebral cortex.