Memory disorders following focal neocortical damage.

Two aspects of memory defects following circumscribed neocortical lesionare considered. First, the selective impairment involving one category of stimuli (e.g. faces, colours) or a specific mnestic ability (spatial orientation). The deficit affects "new" as well as "old" memories and suggests that engrams are located in discrete cortical areas. The second issue concerns the relation of the hemispheric side of lesion to memory of non-verbal visual material, as a function of the differential utilization of the visual and verbal code in carrying out the task. Short-term memory tests are performed poorly by aphasics. In long-term memory tests, the performance depends on the nature of the task; in the early stages of paired-associate learning aphasics are impaired, on recurring figure recognition no hemispheric difference emerges, on sequential memory right brain-damaged patients have the poorest scores.