RT Journal Article
SR Electronic
T1 Hemispheric Lateralization in the Cortical Motor Preparation for Human Vocalization
JF The Journal of Neuroscience
JO J. Neurosci.
FD Society for Neuroscience
SP 1600
OP 1609
DO 10.1523/JNEUROSCI.21-05-01600.2001
VO 21
IS 5
A1 Yasuo Terao
A1 Yoshikazu Ugawa
A1 Hiroyuki Enomoto
A1 Toshiaki Furubayashi
A1 Yasushi Shiio
A1 Katsuyuki Machii
A1 Ritsuko Hanajima
A1 Masami Nishikawa
A1 Nobue K. Iwata
A1 Yuko Saito
A1 Ichiro Kanazawa
YR 2001
UL http://www.jneurosci.org/content/21/5/1600.abstract
AB To investigate the cortical information processing during the preparation of vocalization, we performed transcranial magnetic stimulation (TMS) over the cortex while the subjects prepared to produce voice in response to a visual cue. The control reaction time (RT) of vocalization without TMS was 250–350 msec. TMS prolonged RT when it was delivered up to 150–200 msec before the expected onset of voice (EOV). The largest delay of RT was induced bilaterally over points 6 cm to the left and right of the vertex (the left and right motor areas), resulting in 10–20% prolongation of RT. During the early phase of prevocalization period (50–100 msec before EOV), the delay induced over the left motor area was slightly larger than that induced over the right motor area, whereas, during the late phase (0–50 msec before EOV), it was significantly larger over the right motor area. Bilateral and simultaneous TMS of the left and right motor areas induced delays not significantly different from that induced by unilateral TMS during the early phase, but induced a large delay well in excess of the latter during the late phase. Thus, during the cortical preparation for human vocalization, alternation of hemispheric lateralization takes place between the bilateral motor cortices near the facial motor representations, with mild left hemispheric predominance at the early phase switching over to robust right hemispheric predominance during the late phase. Our results also suggested involvement of the motor representation of respiratory muscles and also of supplementary motor cortex.