DYNAMIC CHANGES IN THE FUNCTIONAL-ORGANIZATION OF THE CEREBRAL-CORTEXARE CORRELATED WITH CHANGES IN PSYCHOPHYSICALLY MEASURED PERCEPTUAL ACUITY

The functional organization of the cerebral cortex in adult owl monkey s has recently been investigated with respect to the psychophysically measured perceptual acuity in the same individual. Monkeys trained at a tactile discrimination task over a restricted skin surface showed a progressive improvement in performance with training. The representati on of the trained skin surface was larger in both cortical areas 3a an d 3b when compared to equivalent untrained skin of the same or contral ateral hand, or on hands of monkeys stimulated in the same way while p erforming an unrelated behavioral task. The time-locked responses to t he tactile stimulus was strongly correlated with the discrimination ab ilities of these skin surfaces. Monkeys trained at an acoustic frequen cy discrimination task showed an equivalent improvement in performance with training. The representation of the frequency range of stimuli u sed in the behavioral task was larger in trained monkeys than in untra ined monkeys or in monkeys exposed to the same stimuli while performin g an unrelated task. The cortical area of representation of these freq uency ranges was strongly correlated with the psychophysically measure d acuity. These studies suggest that the functional organization of th e neocortex is continuously changing to account for the changes of an individual's perceptual abilities.