EFFECTS OF AGING ON TOPOGRAPHIC ORGANIZATION OF SOMATOSENSORY CORTEX

DEFICITS in limb coordination and decreased motor activity have been d escribed in old rats older than 24 months, an approved animal model in ageing research. We investigated the implications of age-related decl ine of sensorimotor performance by studying the functional cortical or ganization of aged rats. The cutaneous receptive fields of the hindpaw representations in somatosensory cortex and the cortical areas excite d by tactile point-stimulation were enlarged and highly overlapping in old rats when compared with young rats. This gives rise to a complete loss of topographic detail. These functional changes were correlated with the rat's individual walking patterns, indicating that age-relate d deficits in sensorimotor performance are paralleled by degradation o f the functional representations in the ageing nervous system.