Temporal progression of cortical reorganization following nerve injury.

Damage to peripheral nerves of adult mammals causes reorganization of somatosensory maps in the cerebral cortex. An understanding of the temporal progression of cortical changes is important for understanding the underlying mechanisms. The present experiments utilized neurophysiological recordings to analyze the time course of reorganization in the S-I cortical hindpaw area in adult rats. Following loss of sciatic inputs, the cortical area responding to low threshold inputs from the hindpaw saphenous nerve expands. A brief, early onset period of rapid expansion is followed by a prolonged period of slow increase. The temporal progression suggests that early onset changes condition the central nervous system for later changes.