OPEN ACCESS Jacobs Journal of Physical Rehabilitation Medicine Excitability of the Ipsilateral Motor and Premotor Cortices during Unilateral Finger Movements: A Combined fMRI and TMS Study Ah-Young Jun 1 , Suk Hooh Ohn 2 , SeungHo Ahn 2 , Kwang-Ik Jung 2 , Woo-Kyoung Yoo 2,3* 1 Department of Physical Medicine and Rehabilitation, Dongtan Sacred Heart Hospital, Hallym University College of Medicine 2 Department of Physical Medicine and Rehabilitation, Hallym University Sacred Heart Hospital, Hallym University College of Medicine, 3 Hallym Institute for Translational Genomics & Bioinformatics, Hallym University College of Medicine *Corresponding author: Dr. Woo-Kyoung Yoo, Dep. of Physical Medicine and Rehabilitation, 896, Hallym University Sacred Heart Hospital, Pyeoung-chon dong, Dongan-gu, Anyang, Gyeonggi-do 430-070, Republic of Korea, Tel: +82-31-380-3860; Email: mdwooky@gmail.com, wooky@hallym.ac.kr Received: 06-01-2015 Accepted: 07-29-2015 Published: 08-05-2015 Copyright: © 2015 Woo-Kyoung Research Article Cite this article: Yoo W K. Excitability of the Ipsilateral Motor and Premotor Cortices during Unilateral Finger Movements: A Combined fMRI and TMS Study. J J Physical Rehab Med. 2015, 1(2): 006. Abstract There was a considerable confusion concerning the brain areas that contributes to ipsilateral activity during unilateral finger movement. Limited evidence suggested engagement of the ipsilateral dorsal premotor cortex (PMd) more than the ipsilateral primary motor cortex (M1) only in functional magnetic resonance imaging (fMRI). In this study, we aimed to delineate the physiological changes obtained by transcranial magnetic stimulation (TMS) in the ipsilateral M1 during unilateral hand movement by comparing it with the functional magnetic resonance imaging (fMRI) activity obtained from M1 and PMd within the same set of subjects. The motor evoked potential (MEP) amplitudes changes were well correlated with the relative hemodynamic changes of the ipsilateral PMd, but they were not correlated with those of the ipsilateral M1 on the fMRI. These results support the notion that the activities of the ipsilateral PMd mediate the changes of excitability in the ipsilateral M1 during unilateral finger movements. Keywords: Excitability; Dorsal Premotor Cortex; Primary Motor Cortex; Transcranial Magnetic Stimulation; Functional Magnetic Resonance Imaging Introduction The previous functional imaging studies have demonstrated that ipsilateral motor cortex activation occurred during complex motor tasks [1,2] and upon non-dominant hand movement in healthy volunteers [3,4]. While the functional role of ipsilateral activation is still a matter of debate, [2,3] Verstynen et al [5]. described that the ipsilateral activation is not necessarily related to the execution of complex movements but is rather related to higher level of controls associated with action retrieval, preparation, and/or selection of the ipsilateral motor cortex. This view is in line with the results that were shown in patients with lesions of the central motor systems [6]. A controversial issue that needs to be addressed here is the location of the ipsilateral activity. Many studies demonstrated ipsilateral motor cortex