Auditory lateralization and planum temporale asymmetry.

Morphological left-right asymmetry of the planum temporale was measured using in vivo magnetic resonance morphometry in 52 normal volunteers. Laterality indices of four verbal dichotic tests differing in stimulus material, stimulus presentation or stimulus reproduction were correlated with the degree of anatomical planum temporale asymmetry. None of these correlations reached a level of statistical significance. In addition, there was no difference in the degree of planum asymmetry between subjects with a dichotic right-ear or left-ear advantage. A possible reason for this lack of a relationship between auditory and anatomical lateralization could be that asymmetrical performance on dichotic listening is unrelated to superior temporal auditory functions.