Modulations of the auditory M100 in an imitation task
Models of speech production explain event-related suppression of the auditory cortical response as reflecting a comparison between auditory predictions and feedback. The present MEG study was designed to test two predictions from this framework: (1) whether the reduced auditory response varies as a function of the mismatch between prediction and feedback; (2) whether individual variation in this response is predictive of speech-motor adaptation.
Participants alternated between online imitation and listening tasks. In the imitation task, participants began each trial producing the same vowel (/e/) and subsequently listened to and imitated auditorily-presented vowels varying in acoustic distance from /e/.
Results replicated suppression, with a smaller M100 during speaking than listening. Although we did not find unequivocal support for the first prediction, participants with less M100 suppression were better at the imitation task. These results are consistent with the enhancement of M100 serving as an error signal to drive subsequent speech-motor adaptation.