Increased corticospinal excitability after 5 Hz rTMS over the human supplementary motor area

Transcranial magnetic stimulation (TMS) can produce effects not only at the site of stimulation but also at distant sites to which it projects. Here we examined the connection between supplementary motor area (SMA) and the hand area of the primary motor cortex (M1 Hand ) by testing whether prolonged...

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Bibliographic Details
Published in:The Journal of physiology 2005-01, Vol.562 (1), p.295-306
Main Authors: Matsunaga, Kaoru, Maruyama, Atsuo, Fujiwara, Toshiyuki, Nakanishi, Ryoji, Tsuji, Sadatoshi, Rothwell, John C.
Format: Article
Language:English
Subjects:
Adult
Cerebral Cortex - physiology
Electric Stimulation
Electromyography
Foot - innervation
Foot - physiology
Functional Laterality - physiology
H-Reflex - physiology
Hand - innervation
Hand - physiology
Humans
Motor Cortex - physiology
Muscle Contraction - physiology
Muscle, Skeletal - physiology
Spinal Cord - physiology
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Summary:Transcranial magnetic stimulation (TMS) can produce effects not only at the site of stimulation but also at distant sites to which it projects. Here we examined the connection between supplementary motor area (SMA) and the hand area of the primary motor cortex (M1 Hand ) by testing whether prolonged repetitive TMS (rTMS) over the SMA can produce changes in excitability of the M1 Hand after the end of the stimulus train. We evaluated motor-evoked potentials (MEPs) and the cortical silent period (CSP) evoked by a single-pulse TMS, short-interval intracortical inhibition (SICI) and intracortical facilitation (ICF) produced by a paired-pulse TMS, and forearm flexor H reflexes before and after 750 pulses of 5 Hz rTMS over SMA at an intensity of 110% active motor threshold (AMT) for the first dorsal interosseous (FDI) muscle. The amplitude of MEPs recorded from the right FDI muscle at rest as well as during voluntary contraction increased for at least 10 min after the end of rTMS, although the duration of the CSP, SICI and ICF did not change. There was no effect on H reflexes in the flexor carpi radialis muscle, even though the amplitude of the MEP obtained from the same muscle increased after rTMS. The effects on MEPs depended on the intensity of rTMS and were spatially specific to the SMA proper. We suggest that 5 Hz rTMS over SMA can induce a short-lasting facilitation in excitability of the M1 Hand compatible with the anatomical connections between SMA and the M1 Hand .
ISSN:0022-3751
1469-7793
DOI:10.1113/jphysiol.2004.070755