Intermittent theta-burst stimulation induces correlated changes in cortical and corticospinal excitability in healthy older subjects

Publication date: December 2017
Source:Clinical Neurophysiology, Volume 128, Issue 12
Author(s): Tamara Gedankien, Peter J. Fried, Alvaro Pascual-Leone, Mouhsin M. Shafi
ObjectiveWe studied the correlation between motor evoked potentials (MEPs) and early TMS-evoked EEG potentials (TEPs) from single-pulse TMS before and after intermittent Theta Burst Stimulation (iTBS) to the left primary motor cortex (M1) in 17 healthy older participants.MethodsTMS was targeted to the hand region of M1 using a MRI-guided navigated brain stimulation system and a figure-of-eight biphasic coil. MEPs were recorded from the right first dorsal interosseous muscle using surface EMG. TEPs were extracted from a 61-channel EEG recording. Participants received 90 single TMS pulses at 120% of resting motor threshold before and after iTBS.ResultsAcross all participants, the change in N15-P30 TEP and MEP amplitudes were significantly correlated (r=0.69; p<0.01). Average TEP responses did not change significantly after iTBS, whereas MEP amplitudes showed a significant increase.ConclusionsChanges in corticospinal reactivity and cortical reactivity induced by iTBS are related. However, the effect of iTBS on TEPs, unlike MEPs, is not straightforward.SignificanceOur findings help elucidate the relationship between changes in cortical and corticospinal excitability in healthy older individuals. Going forward, TEPs may be used to evaluate the effects of theta-burst stimulation in non-motor brain regions.



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