Evidence of the voice-related cortical potential: an electroencephalographic study.

The Bereitschaftspotential (BP) is a slow negative-going cortical potential associated with preparation for volitional movement. Studies since the 1960s have provided evidence for a BP preceding speech-related volitional motor acts. However, the BP associated specifically with phonation [corrected] has not to date been systematically investigated. The current investigation utilizes a novel experimental design to address methodological confounds typically found in studies of movement-related cortical potentials, to demonstrate the existence and localization of generators for the voice-related cortical potential (VRCP). Using high-density EEG, we recorded scalp potentials in preparation for voicing and controlled [corrected] exhalation in a stimulus-induced voluntary movement task. Results showed a slow, increasingly negative cortical potential in the time window of of a standard BP prior [corrected] to the mean onset of phonation. This VRCP peaked at a greater amplitude and shorter latency than the BP associated with exhalation alone. Region analysis exhibited a steeper slope of the late VRCP in the primary motor area (M1) than that in the Supplementary [corrected] Motor Area (SMA), reflecting the complexity of motor movements and control necessary for voicing. Additionally, the late VRCP offset in M1 (-400 ms) was later than that in the SMA (-600 ms), possibly reflecting later engagement of primary motor areas following motor preparation in premotor areas [corrected] Further examination of the spatiotemporal change of the VRCP yielded source models indicating [corrected] involvement of the cortical regions [corrected] responsible for the initiation and continuation of phonation. Sources were localized to the middle frontal gyri and M1, bilaterally. Additional sources were localized to bilateral cerebellum and occipital lobe [corrected]