Motor induced
suppression of auditory cortex
Srikantan S.
Nagarajan
Biomagnetic Imaging
Laboratory, Department of Radiology, UCSF,
Sensory responses to stimuli that are triggered by a self-initiated motor-act are suppressed when compared with the response to the same stimuli triggered externally, a phenomenon referred to as motor-induced suppression (MIS) of sensory cortical feedback. Studies in the somatosensory system suggest that such suppression might be sensitive to delays between the motor act and the stimulus-onset. A recent study in the auditory system suggests that such MIS develops rapidly. Here, we characterize the properties of MIS, by examining the M100 response from auditory cortex to a simple tone triggered by a button press. In experiment 1, we found that MIS develops for zero delays but does not generalize to non-zero delays. In experiment 2, we found that MIS developed for 100 ms delays within 300 trials and occurs in excess of auditory habituation. In experiment 3, we found that unlike MIS for zero-delays, MIS for non-zero delays does not exhibit sensitivity to sensory, delay or motor-command changes. These results are discussed in relation to suppression to self-produced speech and a general model of sensory motor control.