Shin Hae-Won, Sohn Young H, Hallett Mark
Department of Neurology, Brain Research Institute, Yonsei University College of Medicine, 134 Shinchon-dong, Seodaemun-gu, Seoul 120-752, South Korea.
Clin Neurophysiol. 2009 Apr;120(4):816-9. doi: 10.1016/j.clinph.2009.02.004. Epub 2009 Mar 18.
Surround inhibition (SI) in the motor system is an essential mechanism for the selective execution of desired movements. To investigate the relationship between the efficiency of SI operation in the motor system and handedness, we performed a transcranial magnetic stimulation (TMS) study in 10 healthy, right-handed volunteers.
TMS was set to be triggered by self-initiated flexion of the index finger at different intervals ranging from 3 to 1000 ms. Average motor evoked potential (MEP) amplitudes obtained from self-triggered TMS were normalized to average MEPs of the control TMS at rest and expressed as a percentage. Normalized MEP amplitudes of the adductor digiti minimi (ADM) and the flexor digitorum superficialis (FDS) muscles were compared between the dominant and non-dominant hands.
During index finger flexion, MEP amplitudes of the ADM in the dominant hand were suppressed but not in the non-dominant hand, while MEP amplitudes of the FDS were comparably enhanced in both hands. F-wave amplitudes of ADM were comparably enhanced during index finger flexion in both hands.
These results suggest that the functional operation of SI in the motor system is more efficient in the dominant hand than the non-dominant hand. More efficient SI in the dominant hand could lead to greater dexterity in the dominant hand.
Hemispheric asymmetry of SI might be able to serve as a neurophysiological proxy for handedness.
运动系统中的周围抑制（SI）是选择性执行期望动作的重要机制。为了研究运动系统中SI运作效率与利手之间的关系，我们对10名健康的右利手志愿者进行了经颅磁刺激（TMS）研究。
TMS设定为由食指自主发起的不同间隔（3至1000毫秒）的屈曲触发。将自触发TMS获得的平均运动诱发电位（MEP）幅度相对于静息时对照TMS的平均MEP进行归一化，并表示为百分比。比较优势手和非优势手的小指展肌（ADM）和指浅屈肌（FDS）的归一化MEP幅度。
在食指屈曲过程中，优势手的ADM的MEP幅度受到抑制，而非优势手则未受抑制，而FDS的MEP幅度在两只手中均有相应增强。双手在食指屈曲过程中ADM的F波幅度均有相应增强。
这些结果表明，运动系统中SI的功能运作在优势手中比在非优势手中更有效。优势手中更有效的SI可能导致优势手具有更高的灵活性。
SI的半球不对称性可能能够作为利手的神经生理学指标。
