Some anatomo-clinical aspects of phonemic and semantic comprehension disorders in aphasia.

Abstract

60 aphasic patients, affected by localized lesions of the left hemisphere and classed as Broca's, Global, Conduction, Amnestic or Wernicke's aphasia received 1 phoneme discrimination test and 3 semantic-lexical discrimination tests. The aim of the study consisted in investigating the relationships between phoneme and semantic-lexical discrimination disorders, the clinical form of aphasia and the anatomic locus of the cerebral lesion. The results were not consistent with the claim that comprehension disorders of Wernicke's aphasic patients can be traced back to a phoneme discrimination disorder, since Wernicke's aphasics were not more impaired than other aphasic groups and since patients with lesions localized in the temporal lobe performed quite well in the phoneme discrimination test. Semantic discrimination disorders were very frequent and severe in patients classified as Wernicke's, Amnesic or Global aphasia, whereas they were much less relevant in patients classified as Broca's or Conduction aphasia. As for the locus of the lesion, left temporal damage severely impaired semantic-lexical discrimination without affecting phoneme discrimination (a finding which supports the assumption of a selective involvement of the temporal lobe in semantic-lexical memory). On the other hand, patients with damage localized in the left frontal lobe, obtained poor scores both on semantic-lexical discrimination tasks and on phoneme discrimination tests.