Understanding the neural mechanisms involved in sensory control of voice production

Abstract

Auditory feedback is important for the control of voice fundamental frequency (F0). In the present study we used neuroimaging to identify regions of the brain responsible for sensory control of the voice. We used a pitch-shift paradigm where subjects respond to an alteration, or shift, of voice pitch auditory feedback with a reflexive change in F0. To determine the neural substrates involved in these audio-vocal responses, subjects underwent fMRI scanning while vocalizing with or without pitch-shifted feedback. The comparison of shifted and unshifted vocalization revealed activation bilaterally in the superior temporal gyrus (STG) in response to the pitch shifted feedback. We hypothesize that the STG activity is related to error detection by auditory error cells located in the superior temporal cortex and efference copy mechanisms whereby this region is responsible for the coding of a mismatch between actual and predicted voice F0.

Figure 1

Experimental design for a single trial of volume acquisition and expected HRF

Figure 2

Group average vocal responses to downwards (a) and upwards (b) pitch shifted stimuli. The pitch shift occurred at time t=0. Figure shows mean responses in cents with standard error bars (n=11).

Figure 3

BOLD response for a comparison of unshifted vocalization condition compared to the baseline rest condition (NoShift-Rest). (b) Bold responses for the shifted vocalization condition compared to the baseline rest condition (Shift-Rest). Data shown represents group responses (n=12) from a random effects analysis.

Figure 4

(a) Fixed effects (p<0.05, FWE) and (b) random effects (p<0.001) analysis of BOLD responses to the vocalization pitch shift – no shift contrast (n=12).