Double dissociation between picture naming and comprehension: an electrostimulation study.

We performed a cortico-subcortical language electrical mapping, using a picture naming task and a semantic test of association, during resection of a left posterior temporal glioma in an awake patient. Two discrete naming sites were identified in the posterior part of the left superior temporal gyrus, plus a third distinct site between the two previous areas, inducing specific comprehension disorders without anomia when stimulated. After resection, white matter stimulation elicited anomia without comprehension disorder. We suggest the existence of distinct naming and comprehension systems, which can explain the possibility of a double dissociation aphasic syndrome: one with normal undertanding but naming error, reflecting post-semantic problems of access to the phonological form; the other with correct naming but without normal comprehension, testifying to a direct non-semantic pathway for naming.