Abstract
Integrating auditory and motor information often requires precise timing as in speech and music. In humans, the position of the ventral premotor cortex (PMv) in the dorsal auditory stream renders this area a node for auditory-motor integration. Yet, it remains unknown whether the PMv is critical for auditory-motor timing and which activity increases help to preserve task performance following its disruption. 16 healthy volunteers participated in two sessions with fMRI measured at baseline and following rTMS (rTMS) of either the left PMv or a control region. Subjects synchronized left or right finger tapping to sub-second beat rates of auditory rhythms in the experimental task, and produced self-paced tapping during spectrally matched auditory stimuli in the control task. Left PMv rTMS impaired auditory-motor synchronization accuracy in the first sub-block following stimulation (p<0.01, Bonferroni corrected), but spared motor timing and attention to task. Task-related activity increased in the homologue right PMv, but did not predict the behavioral effect of rTMS. In contrast, anterior midline cerebellum revealed most pronounced activity increase in less impaired subjects. The present findings suggest a critical role of the left PMv in feed-forward computations enabling accurate auditory-motor timing, which can be compensated by activity modulations in the cerebellum, but not in the homologue region contralateral to stimulation.
Highlights
An important research goal in basic and clinical neuroscience is to understand recovery of cognitive function
Control 1 - Effect on motor timing: Coefficient of variability in the control condition (CVCC). To ensure that this effect was related to auditory-motor timing and not just to motor timing variability, coefficient of variation (CV) of tap-to-tap’ asynchrony was computed in the control condition (CC), in which subject produced regular self-paced tapping during an auditory stimulus, that spectrally matched the auditory rhythms, where tap’ is the time at which a tap should have occurred according to the mean inter-tap-interval in the respective trial
The present combined repetitive transcranial magnetic stimulation (rTMS)-fMRI experiment probed the critical role of the left ventral premotor cortex (PMv) in auditorymotor timing, and investigated task-dependent activity increases that help to preserve auditory-motor synchronization following its disruption
Summary
An important research goal in basic and clinical neuroscience is to understand recovery of cognitive function. As a part of the dorsal auditory stream, the ventral premotor/ frontal opercular region (PMv) has been shown to be a node for auditory-motor integration, with regard to sequential auditory patterns like speech or music [1,2,3], in which timing is essential. Both its anatomical position and its functional properties suggest that this region may play a critical role in auditory-motor timing. The PMv has been shown to possess direct corticospinal outputs and project to the primary motor cortex via association fibres [8,9], as well as to its homologue, the contralateral PMv [10]
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