Dynamic cortical imaging of speech compensation for auditory feedback perturbations

Abstract

Understanding how auditory feedback is processed and used during speech production is a long-standing issue, one that has classically been investigated by looking at how altering auditory feedback affects speech. Recently, the advent of functional neuroimaging methods has also allowed examination of how producing speech affects the neural processes serving auditory perception. Here, whole-head magnetic source imaging (MSI) was used to monitor cortical activity as speakers responded to brief perturbations of the pitch or amplitude of their speech. Prior studies have shown that such perturbations cause compensatory responses in speech motor output. MSI recordings were acquired at the onset of feedback perturbations as the subject continuously vocalized and also when the subject passively listened to recordings of the perturbed feedback. A response to the perturbations was found around auditory cortex between 100 and 400 ms postperturbation that was enhanced while subjects vocalized, as compared to when they passively listened. The size of this response enhancement was a significant predictor of how much a subject compensated for the feedback perturbation. Time-frequency optimized adaptive spatial filtering was also used to localize cortical activations that correlated significantly with degree of compensation across subjects. [Work supported by NSF grant BCS-0349582 and NIH/NIDCD grant R01-DC006435.]