LATERALIZED EFFECT OF UNILATERAL SOMATOSENSORY CORTEX CONTUSION ON BEHAVIOR AND CORTICAL REORGANIZATION

Previous studies have shown that rats recover function after unilatera l somatosensory cortex lesions, possibly by transfer of information pr ocessing to other brain areas not normally involved in those functions . In the present study, adult rats underwent unilateral contusions of the somatosensory cortex with ablation of the barrel receptor field. B ehavioral testing with modified beam-walking and sensory neglect tasks demonstrated persistent somatosensory deficits in rats with left cont usions but no apparent deficits in right injured animals. After 2 mont hs, the [C-14]2-deoxyglucose (2-DG) method was used to show the metabo lic activity produced by unilateral stimulation of the facial vibrissa e. In left injured animals, cortical metabolic activity rostral and ca udal to the injury site was depressed both under basal conditions and during right vibrissal stimulation. On the other hand, comparison of t he pattern of [C-14]2-DG uptake in the intact, right cortex revealed c hanges in the pattern of glucose utilization associated with left inju ry combined with right vibrissal stimulation. Pattern changes were qua ntified by measuring the area in which glucose utilization was within the highest 25% of this range (high activity area; HAA). Right vibriss al stimulation in left injured rats caused an expansion of this HAA in the intact occipital/temporal cortex. Also, in the intact somatosenso ry cortex of left injured rats, there was an enlarged HAA whether or n ot vibrissal stimulation was performed. Thus, a combination of depress ed peri-injury metabolic activity and aberrant activity in remote brai n areas occurs following unilateral somatosensory cortex injury. It re mains to be shown whether these factors ameliorate or contribute to pe rsistent behavioral deficits.