Metabolic alterations in rat somatosensory cortex following unilateral vibrissal removal

Local cerebral metabolic rates for glucose were studied by [14C]-2-deoxyglucose autoradiography in adult rats following acute and chronic unilateral deafferentation, with particular attention to the barrel field regions of the primary somatosensory cortex. Deafferentation was produced by permanently removing all of the large whiskers (vibrissae) on one side of the face. Data from experimental animals were then compared to data from sham-operated controls at 1, 5, 10, 15, 30, and 60 days after deafferentation. The rate of glucose utilization was maximally depressed at day 1 in the deafferented barrel field. After that, there was a progressive recovery of glucose utilization toward control levels at each subsequent time point. In contrast, glucose utilization in the barrel field associated with the intact set of whiskers increased by day 5 and remained elevated throughout the duration of the experiment. Similar patterns of altered cerebral metabolism were observed following unilateral infraorbital nerve transection. These results demonstrate that interference with normal somatosensory input causes a transient decrease in glucose metabolism of the contralateral cortical barrel-field and, in addition, causes long-term increments in glucose metabolism in the ipsilateral cortical barrel field--a structure not normally influenced by acute manipulation.