PHYSIOLOGICAL-CHANGES DURING RECOVERY FROM A PRIMATE DORSAL COLUMN LESION

The evoked potential (EP) over primary somatosensory cortex (SI) was m onitored before and after a complete lesion of the primate dorsal colu mn (DC) pathway on one side. The EP was elicited by electrocutaneous o r mechanical stimulation of either foot, and was recorded from the con tralateral cortical surface for periods of up to 3 months after the le sion. The amplitudes of the three major peaks (P20, N50, and P90) of t he cortical somatosensory EP were significantly reduced following inte rruption of the contralateral DC. Over weeks following the lesion, the re was a significant increase in amplitude of the P90 component of the EP that was not evident in the other peaks. The postlesion increases in P90 amplitude were correlated with improved performance on a task t hat required grasping with either foot, suggesting that behavioral rec overy from a DC lesion results in part from neural plasticity, as oppo sed to a simple relearning of the task.