| 제목 |
Optimal Site for rTMS to Improve Motor Function: Anatomical Hand Knob vs. Hand Motor Hotspot |
| 소속 |
Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea, Department of Physical and Rehabilitation Medicine, Center for Prevention and Rehabilitation, Heart Vascular Stroke Institute1, SAIHST, Sungkyunkwan University, Seoul, Republic of Korea, Department of Health Sciences and Technology2 |
| 저자 |
Heegoo Kim1,2*, Jinuk Kim1,2, Hwang-Jae Lee1,2, Jungsoo Lee1, Yoonju Na1, Won Hyuk Chang1, Yun-Hee Kim1,2† |
Objective
Low-frequency repetitive transcranial magnetic stimulation (rTMS) at or below 1 Hz over the motor cortex is widely used to inhibit abnormally increased contralesional excitability in stroke patients. To modulate corticospinal excitability, accurate determination of the stimulation site is important to maximize the effects of rTMS. In the present study, we aimed to demonstrate the effects of low-frequency rTMS over the dominant motor cortex determined by two different targeting methods using the neurophysiological and behavioral assessments in the same set of healthy participants.
Materials and Methods
Ten healthy right-handed volunteers without any neurological disorders were enrolled. The anatomical hand knob (HK) identified from individual magnetic resonance imaging and the transcranial magnetic stimulation (TMS) induced hand motor hotspot (hMHS) by recording motor evoked potentials (MEPs) in the contralateral first dorsal interosseous muscle were determined. All participants underwent three conditions of 1 Hz rTMS intervention; rTMS application over the HK (HK-rTMS), rTMS application over the hMHS (hMHS-rTMS), and sham-rTMS. All volunteers underwent low-frequency rTMS over the dominant hemisphere. They were assessed before and immediately after each rTMS intervention by the following tests to evaluate the corticomotor excitability and motor function of the non-dominant hand: (1) neurophysiologic assessment including resting motor threshold (rMT) and MEP amplitude, and (2) behavioral motor function assessment including the nine-hole pegboard test and serial reaction time task (SRTT).
Results
The cortical mapping showed that the hMHS was located anteriorly and laterally compared to the HK. The MEP amplitude, the execution time of the nine-hole pegboard test, and SRTT response time showed significantly positive changes only after the hMHS-rTMS. Conversely, most measurements did not change in HK-rTMS and sham-rTMS except for skill index which was significantly improved in all groups. However, significant time and condition interaction effect was not observed between the conditions.
Conclusions
Based on the results of the present study, the location of hMHS-induced MEPs was not in accordance with the anatomical HK. As a result, adopting 1 Hz rTMS over these two different locations induced different behavioral and neurophysiological changes. To maximize the balancing effect by low-frequency rTMS, the optimal target site should be considered as a motor hotspot induced by single-pulse TMS rather than the anatomical structure.
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