Research Abstract
Objective: To investigate whether motor
suppression is an active process, and to clarify its somatotopic
organization, we investigated cortico-motoneuronal excitability using
transcranial magnetic stimulation
(TMS) during the Stop-signal task.
Methods: Subjects were asked to press a button following a Go cue; a Stop-signal
followed the Go cue by
a certain time delay in 25% of trials, indicating to subjects that they were not
to press the button. TMS was
given to the primary motor area of the left or right-hand or leg at variable
time delays. Motor evoked
potentials (MEPs) were recorded from the hand and leg muscles bilaterally.
Results: When TMS was delivered 400 ms after the Go cue, there was significant
suppression of the MEPs
of the bilateral hand and leg muscles during successful Stop trials, but not
during failed Stop trials.
Conclusions: The voluntary stopping of movement in the Stop-signal task is an
active process, which
likely suppresses not only the cortico-motoneuronal excitability of the
task-performing hand, but also
causes the widespread suppression of the motor system.
Significance: Studies in the normal physiology of response inhibition would be
of help in understanding
the pathophysiology of neuro-psychiatric disorders associated with deficits in
motor suppression.
2009 International Federation of Clinical Neurophysiology. Published by Elsevier
Ireland Ltd. All rights
reserved.
Research Authors
Reda Badry a, Tatsuya Mima a,*, Toshihiko Aso a, Masahiro Nakatsuka a, Mitsunari Abe a, Dina Fathi a,<br> Nageh Foly b, Hamdy Nagiub b, Takashi Nagamine a, Hidenao Fukuyama a<br> a Human Brain Research Center, Kyoto University Graduate School of Medicine
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