Shared and distinct neural correlates of vowel perception and production
Résumé
Although a functional distinction between frontal motor sites for speech production and temporal auditory sites for speech perception has long been postulated, some recent neurobiological studies rather argue for a tight connection between speech perception and production systems. In the present functional magnetic resonance imaging study, we investigated whether common brain areas might participate in both vowel perception and production. In order to minimize scanner noise and movement-related imaging artifacts, a sparse sampling acquisition technique was used where participants produced or passively listened to a vowel (previously recorded from their own voices) during a silent interval between successive image acquisitions. Direct comparisons between speaking and listening conditions revealed specific activations for speaking in the sensorimotor cortex, the supplementary motor area, the basal ganglia and the posterior cingulate gyrus. In addition, specific reduced responses were also observed in the supramarginal gyrus, which are likely to reflect motor-to-sensory feedback control mechanisms. Finally, a conjunction analysis showed a shared neural network for vowel perception and production, with common activations in the left inferior frontal gyrus and in the superior temporal gyrus/sulcus bilaterally. Interestingly, although previous studies have demonstrated activation of the ventral premotor cortex in passive speech perception, the overlapping frontal activations were here largely confined to the inferior frontal gyrus. The absence of response in the ventral premotor cortex during vowel perception might be due to the perception of participant's own voice that does not explicitly require a mapping of perceived vowel onto internal motor representations of articulatory gestures.