Primary auditory cortex activation by visual speech: an fMRI study at 3 T

Recent studies have yielded contradictory evidence on whether visual speech perception (watching articulatory gestures) can activate the human primary auditory cortex. To circumvent confounds due to inter-individual anatomical variation, we de¢ned our subjects’ Heschl’s gyri and assessed blood oxygenation-dependent signal changes at 3 Twithin this con¢ned region during visual speech perception and observation of moving circles.Visual speech perception activated Heschl’s gyri in nine subjects, with activation in seven of them extending to the area of primary auditory cortex. Activation was signi¢cantly stronger during visual speech perception than during observation of the moving circles. Further, a signi¢cant hemisphere by stimulus interaction occurred, suggesting left Heschl’s gyrus specialization for visual speech processing. NeuroReport16:125^128 � c 2005 Lippincott Williams & Wilkins.