Effects of localised cerebral lesions and dysphasia on verbal memory

Twenty-nine patients with unilateral left hemisphere lesions, 22 patients with unilateral right hemisphere lesions, and 19 neurological control patients with extracerebral lesions were assessed on verbal memory recall and recognition tests and on a battery of language tests. The left hemisphere group was significantly impaired in memory and language skills. Significant verbal memory impairment was found both in the subgroup of left hemisphere lesion patients whose lesions involved the temporal lobe and in the subgroup whose lesions did not. However, no significant differences between these left hemisphere subgroups' levels of performance on memory tasks emerged, even when dysphasia was taken into account. This study, therefore, fails to support the notion of a specific anatomical correlate of verbal memory impairment within the left hemisphere. Dysphasic subjects were significantly impaired on verbal memory tasks but displayed the same pattern of sensitivity to the effects of word frequency and word concreteness on verbal memory as control subjects, suggesting that the verbal memory of the dysphasic subjects was quantitatively rather than qualitatively impaired. This impairment could not be attributed to deficits in the comprehension or expression of the memory test items, and it is, therefore, proposed that language disturbances may hinder the efficient use of such language based procedures as may subserve verbal memory.