Memory for what it is and memory for what it means: a single case of Korsakoff's amnesia.

A single case of Korsakoff's syndrome, showing classic circumscribed amnesia on traditional neuropsychological tests, performed a number of learning tasks previously used in primates to demonstrate the different anatomical basis of memory systems used to learn about the properties of objects or to learn about rules of responding. The patient (CJ) performed in a manner very similar to lesioned monkeys in that he could learn evaluative tasks (e.g. a red object is nice), but not rule based tasks (e.g. a red object means go left). In consequence CJ learned an object discrimination task in a manner qualitatively different from a group of non-amnesic controls. Although he could not learn rule based tasks, CJ could perform them once he had been given the rule. Detailed analysis of learning showed that CJ could choose the object he had chosen previously, but could not say where it had been or whether he had been rewarded. Furthermore he could recognise a word as familiar, while not remembering its source. We propose that he has a specific impairment in a memory system concerned with the representation of the signification of objects in particular contexts, while representation of the properties of objects remains intact.