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Smooth pursuit eye movement preferentially facilitates motor-evoked potential elicited by anterior–posterior current in the brain

Hiraoka, Koichi; Ae, Minori; Ogura, Nana; Komuratani, Sayo; Sano, Chisa; Shiomi, Keigo; Morita, Yuji; Yokoyama, Haruka

doi: 10.1097/WNR.0000000000000075
MOTOR SYSTEMS
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Neural interaction between the eye and hand movement centers must be a critical part of the mechanism underlying eye–hand coordination. One of the previous findings supporting this view is smooth pursuit eye movement-induced suppression of motor-evoked potential (MEP) in the hand muscles. The purpose of this study was to determine which descending volleys contributing to MEP are preferentially modulated by smooth pursuit eye movement. MEP in the first dorsal interosseous muscle was elicited by different directions of current in the brain during the steady-state phase of smooth pursuit eye movement. Smooth pursuit eye movement facilitated MEP elicited by anterior–posterior (AP) current, but this effect was not seen in MEP elicited by lateromedial or posterior–anterior current. Latency of MEP elicited by AP current was significantly longer than latencies of MEPs elicited by other directions of current, indicating that AP current in the brain predominantly elicited later I-waves. We conclude that smooth pursuit eye movement in the steady-state phase preferentially facilitates MEP predominantly elicited by later I-waves generated by AP current in the brain.

College of Health and Human Sciences, Osaka Prefecture University, Habikino, Osaka Prefecture, Japan

Correspondence to Koichi Hiraoka, PhD, College of Health and Human Sciences, Osaka Prefecture University, Habikino 3-7-30, Habikino, Osaka 583-8555, Japan Tel: +81 72 950 2875; fax: +81 72 950 2131; e-mail: hiraoka@rehab.osakafu-u.ac.jp

Received September 26, 2013

Accepted October 3, 2013

© 2014 Wolters Kluwer Health | Lippincott Williams & Wilkins