"Paradoxic" ear extinction in dichotic listening: possible anatomic significance.

"Paradoxic" extinction in dichotic listening tasks has been attributed to lesions in the interhemispheric auditory pathways, the anatomic courses of which are unknown. The localization of cerebral lesions related to abnormal patterns of dichotic listening was studied in computerized tomographic (CT) scans with a method of anatomic templates. Paradoxic extinction was found consistently with lesions near the lateral wall of the lateral ventricles at the level of the trigone in both left and right hemispheres. On the basis of these findings, we propose that the pathway leaves the auditory cortex traveling backward and upward to arch around the lateral ventricles and join the callosum in its posterior region.