Details

Autor(en) / Beteiligte

• Ogata, Katsuya
• Nakazono, Hisato
• Uehara, Taira
• Tobimatsu, Shozo

Titel

Prestimulus cortical EEG oscillations can predict the excitability of the primary motor cortex

Ist Teil von

• Brain stimulation, 2019-11, Vol.12 (6), p.1508-1516

Ort / Verlag

United States: Elsevier Inc

Erscheinungsjahr

2019

Quelle

Access via ScienceDirect (Elsevier)

Beschreibungen/Notizen

• The motor evoked potentials (MEPs) elicited by single-pulse transcranial magnetic stimulation (TMS) vary considerably at rest, but the mechanism underlying this amplitude variation is largely unknown. We hypothesized that prestimulus EEG oscillations modulate the subsequent MEPs in a state-dependent manner. We studied the relationship between prestimulus alpha/beta oscillations and MEPs during eyes open (EO)/closed (EC) conditions, and then modulated TMS intensity in the EO condition. Furthermore, we developed an EEG-triggered TMS system (“informed open-loop”) to verify our hypothesis. TMS was applied to the left motor cortex. We first compared EEG power differences between high- and low-amplitude MEP epochs in the EO and EC conditions when using a high TMS intensity. Next, we evaluated the effects of varying TMS intensities (high vs. low) on the EEG–MEP relationship. Finally, we used EEG-triggered TMS to determine whether prestimulus EEG oscillations predicted MEP amplitudes. Prestimulus higher-power alpha/low-beta bands produced larger MEPs only in the high-intensity EO condition. A positive relationship between EEG power and MEP amplitude was observed at C3 and left frontal electrodes. This relationship was obscured when using the lower TMS intensity but was observed in the high-intensity condition at the C3 electrode. EEG-triggered TMS demonstrated that higher alpha power predicted higher MEP amplitudes, but beta power at around 20 Hz did not. A causal relationship between alpha/low-beta oscillations and MEP amplitudes at rest requires high TMS intensity delivered when eyes are open. This association may allow us to develop a new informed open-loop TMS protocol. •We studied the relationship between prestimulus EEG oscillations and MEPs.•High prestimulus alpha/low-beta (10–15 Hz) power induced high MEP amplitudes.•This relationship was weaker in the eyes-closed state or if TMS intensity was low.•EEG-triggered TMS suggested the importance of alpha power.•The EEG–MEP relationship was modulated in a state-dependent manner.