Some tests of the "Sensory Disinhibition" explanation of the psychological effects of frontal lobe damage in man

Abstract

Studies of the effects of frontal lobe lesions in animals and man were discussed in relation to hypotheses of frontal lobe function. It was suggested that the "Sensory Disinhibition" hypothesis provides the most useful account of the results of the animal experiments 0 According to this hypothesis, the deficits resulting from frontal damage are due to a disturbance of attention, brought about by interference with a neurophysiological system which controls the selective inhibition of sensory input. The review of human studies suggested that the sensory disinhibition hypothesis could provide the basis for an explanation of the wide range of impairments produced. To explore this possibility, six experiments were carried out, comparing patients with frontal lobe lesions with those having temporal lesions on tasks concerned with selective attention. In some experiments, data from normal control subjects were also obtained. Experiment 1 (Discrimination Learning) indicated that frontal subjects differed from temporals and controls in accordance with the predictions of the sensory disinhibition hypothesis. The results of Experiments 2 (Visual Search) and 3 (Classification), however, suggested no selective effects due to locus of lesion. In Experiments 4, 5 and 6, the "post-search error", a measure distinguishing frontaIs from temporals in Experiment 'i and thought to reflect "sensory disinhibition", was correlated with the performance of each of the two clinical groups. There was some evidence in Experiments 4 and 6 (but not Experiment 5), of a correlation in the frontal group. It was concluded that the experiments provide only moderate support for the sensory disinhibition hypothesis in relation to the effects of frontal lobe damage in man.