Expansion of stimulus-evoked metabolic activity in monkey somatosensory cortex after peripheral denervation

The 2-deoxy-glucose (2DG) technique was used to study changes in stimulus-evoked metabolic activity in the somatosensory cortex of the squirrel monkey Saimiri sciureus after unilateral digit amputation. Two to 52 weeks after digit 2 on the left hand was removed, a somatic stimulus was applied to digit 3 bilaterally. In area 3b corresponding to the deafferented side of the brain, the area of stimulus-evoked metabolic activity was greater than that on the opposite, control side of the brain within the same animal. The extent of the topographic projection map of 2DG label in area 3b on the deafferented side of the brain was 1.92 to 4.75 times greater than that on the control side. There was no difference, however, in the topographical area of stimulus-evoked metabolic activity between the left and right somatosensory cortices in a normal, unoperated animal. These data suggest that the changes in functional organization observed using electrophysiological recordings in somatosensory cortex after peripheral denervation may have a metabolic substrate.