Kobayashi M, Hutchinson S, Théoret H, Schlaug G, Pascual-Leone A
Laboratory for Magnetic Brain Stimulation, Department of Neurology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
Neurology. 2004 Jan 13;62(1):91-8. doi: 10.1212/wnl.62.1.91.
Disruption of cortical function can improve behavior. Motor cortex (M1) transcallosal interactions are mainly inhibitory; after unilateral damage to M1, there is increased excitability of the unaffected M1. Repetitive transcranial magnetic stimulation (rTMS) of M1 produces a temporary reduction in cortical excitability in the same M1 that outlasts the duration of the rTMS train. The authors hypothesize that reducing cortical excitability of M1 by rTMS may improve motor performance in the ipsilateral hand by releasing the contralateral M1 from transcallosal inhibition.
Sixteen healthy volunteers participated. Using a sequential key-pressing task with the index finger, motor performance was monitored before and after rTMS (1 Hz for 10 minutes with the intensity below motor threshold) applied to the ipsilateral M1, contralateral M1, ipsilateral premotor area, or vertex (Cz).
rTMS of M1 shortened execution time of the motor task with the ipsilateral hand without affecting performance with the contralateral hand. This effect outlasted rTMS by at least 10 minutes, was specific for M1 stimulation, and was associated with increased intracortical excitability in the unstimulated M1.
The authors' results support the concept of an interhemispheric "rivalry." They demonstrate the utility of repetitive transcranial magnetic stimulation to explore the functional facilitation of the unstimulated counterpart motor cortex, presumably via suppression of activity in the stimulated motor cortex and transcallosal inhibition.
皮质功能的破坏可改善行为。运动皮质（M1）的胼胝体间相互作用主要是抑制性的；M1单侧受损后，未受影响的M1兴奋性增加。对M1进行重复经颅磁刺激（rTMS）会使同一M1的皮质兴奋性暂时降低，且这种降低持续时间超过rTMS脉冲串的持续时间。作者推测，通过rTMS降低M1的皮质兴奋性可能通过解除对侧M1的胼胝体抑制来改善同侧手的运动表现。
16名健康志愿者参与。使用食指连续按键任务，在对同侧M1、对侧M1、同侧运动前区或头顶（Cz）施加rTMS（1赫兹，持续10分钟，强度低于运动阈值）前后监测运动表现。
对M1进行rTMS可缩短同侧手执行运动任务的时间，而不影响对侧手的表现。这种效应在rTMS后至少持续10分钟，对M1刺激具有特异性，且与未受刺激的M1皮质内兴奋性增加有关。
作者的结果支持半球间“竞争”的概念。他们证明了重复经颅磁刺激在探索未受刺激的对侧运动皮质功能促进方面的效用，推测是通过抑制受刺激运动皮质的活动和胼胝体抑制来实现的。
