Comparative neuropsychology and Korsakoff's syndrome. II—Two-choice visual discrimination learning

Abstract

Performance by 12 alcoholic Korsakoff patients was compared to that of 15 patients with Huntington's disease, 11 patients with Broca's aphasia, and 13 alcoholic control subjects on two types of two-choice visual discrimination problems which, in brain-damaged monkeys, successfully dissociate deficits of visual perception from those of visual associative learning. Korsakoff and Huntington patients were slow to learn individual discriminations, but eventually performed well on them. Both groups were severely, but differently, impaired on concurrent discrimination tasks in which several pairs of stimuli are presented together within each testing session. It is suggested that the Korsakoffs have a severe deficit of associative learning combined with abnormal sensitivity to interference, whereas the Huntingtons are impaired primarily in visually-based associative learning. Deficits in Korsakoff patients are related to their widespread brain damage which includes limbic-system structures and pre-frontal cortex. Huntington deficits are related to atrophy of frontal and temporal cortex, perhaps consequent to atrophy of the caudate.