• Takenobu Murakami, Kenji Sakuma, Takashi Nomura, Kenji Nakashima, and Isao Hashimoto.
• Department of Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, 36-1 Nishicho, Yonago 683-8504, Japan. takebou@grape.med.tottori-u.ac.jp
• Clin Neurophysiol. 2008 Feb 1; 119 (2): 301-8.

ObjectiveTheta burst transcranial magnetic stimulation (TBS) causes changes in motor cortical excitability. In the present study, somatosensory-evoked potentials (SEPs) and high-frequency oscillations (HFOs) were recorded before and after TBS over the motor cortex to examine how TBS influenced the somatosensory cortex.MethodsSEPs following electric median nerve stimulation were recorded, and amplitudes for the P14, N20, P25, and N33 components were measured and analyzed. HFOs were separated by 400-800 Hz band-pass filtering, and root-mean-square amplitudes were calculated from onset to offset. SEPs and HFOs were measured before and after application of either intermittent or continuous TBS (iTBS/cTBS; 600 total pulses at 80% active motor threshold) over the motor cortex. Motor-evoked potentials (MEPs) and short-interval intracortical inhibition (SICI) of the first dorsal interosseous muscle were examined before and after TBS.ResultsMEPs, SICI, and HFO amplitudes were increased and decreased significantly after iTBS and cTBS, respectively. Wide-band SEPs did not change significantly after TBS.ConclusionsTBS changed the cortical excitability of the sensorimotor cortices. Changes in HFOs after TBS were parallel to those in SICI.SignificanceThe mechanisms of changes in HFOs after TBS may be the same as those in SICI.

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