Several sensory-motor integration regions have been identified in
parietal cortex, which appear to be organized around motor-effectors (e.g.,
eyes,
hands). We investigated whether a sensory-motor integration area might exist for the human
vocal tract. Speech requires extensive sensory-motor integration, as does other abilities such as vocal musical skills. Recent work found that a
posterior superior temporal-parietal region, area Spt, has both sensory (auditory) and motor response properties (for both speech and tonal stimuli).
Brain activity of skilled pianists was measured with
fMRI while they listened to a novel melody and either covertly hummed the melody (
vocal tract effectors) or covertly played the melody on a piano (manual effectors). Activity in area Spt was significantly higher for the covert hum versus covert play condition. A region in the
anterior IPS (aIPS) showed the reverse pattern, suggesting its involvement in sensory-manual transformations. This finding suggests that area Spt is a sensory-motor integration area for
vocal tract gestures.
