Dichotic listening pattern in conduction aphasia.

Judging from classic postmortem reports (cf., Goldstein, 1948; Kleist, 1952; Benson et al., 1973) and from recent studies using CT scanning (Damasio & Damasio, 1979a), conduction aphasia is often associated with damage to the left cortical auditory complex (the primary areas, Brodmann’s fields 41 and 42, and the association area, field 22). It follows that arrival of auditory input in the left temporal lobe via the geniculo-cortical pathway must be precluded or greatly diminished in patients with that syndrome and that conduction aphasics should show a marked extinction to verbal stimuli presented to the right ear in a dichotic listening (DL) task. We report two instances of patients with conduction aphasia in whom there was complete right channel extinction in a verbal DL task, and discuss the functional significance of the phenomenon.