Selective sparing of memory functioning in a patient with amnesia following herpes encephalitis

A patient with amnesia subsequent to herpes encephalitis was assessed on a series of tasks which have been shown to result in normal or near normal performance by amnesic subjects. On a pursuit rotor learning task, our patient performed normally, and continued to show evidence of memory for the skill after a period of 30 days. On a perceptual learning task, which involved the identification of line drawings, he also displayed evidence of learning and long-term retention, but his performance remained below that of control subjects. In two priming experiments, which employed a "case-control" paradigm, performance on homonym-spelling and category item-generation tasks was preceded by exposure to a selected list of words. There was no evidence of differential facilitation in respect of those words used in the initial priming task. The findings point to some degree of selectivity of preserved learning capabilities in amnesia. It is hypothesized that this selectivity may be determined by several variables, including the type of task, the etiology and site of pathology, and the severity of amnesia.