Effects of ageing on topographic organization of somatosensory cortex.

Deficits in limb coordination and decreased motor activity have been described in old rats older than 24 months, an approved animal model in ageing research. We investigated the implications of age-related decline of sensorimotor performance by studying the functional cortical organization of aged rats. The cutaneous receptive fields of the hindpaw representations in somatosensory cortex and the cortical areas excited 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-related deficits in sensorimotor performance are paralleled by degradation of the functional representations in the ageing nervous system.