Neural networks involved in voluntary and involuntary vocal pitch regulation in experienced singers
In an fMRI experiment, we tested experienced singers with singing tasks to investigate neural correlates of voluntary and involuntary vocal pitch regulation. We shifted the pitch of auditory feedback 25 or 200 cents) and singers either: (1) ignored the shift and maintained their vocal pitch or (2) changed their vocal pitch to compensate for the shift. In our previous study, singers successfully ignored and compensated for 200 cent shifts; in the present experiment, we hypothesized that singers would be less able to ignore 25 cent shifts, due to a prepotent, corrective pitch shift response. We expected that voluntary vocal regulation during compensate tasks would recruit the anterior portion of the rostral cingulate zone (RCZa) and posterior superior temporal sulcus (pSTS) as our earlier study reported; however, we predicted that a different network may be engaged during involuntary responses to 25 cent shifts. Singers were less able to ignore 25 cent shifts than 200 cent shifts, suggesting that pitch shift responses to small shifts are under less voluntary control than responses to larger shifts. While we did not find neural activity specifically associated with involuntary pitch shift responses, compensate tasks recruited a functionally connected network consisting of RCZa, pSTS, and anterior insula. Analyses of stimulus modulated functional connectivity suggest that pSTS and intraparietal sulcus may monitor auditory feedback to extract pitch shift direction in 200 cent tasks, but not in 25 cent tasks, which suggests that larger vocal corrections are under cortical control. During the compensate tasks, the pSTS may interact with the RCZa and anterior insula before voluntary vocal pitch correction occurs.
Neuropsychologia