Corticospinal excitability modulation by pairing peripheral nerve stimulation with cortical states of movement initiation

Abstract

We compare the effects on corticospinal excitability of repeatedly delivering peripheral nerve stimulation at three time points (−30 ms, 0 ms, +50 ms) relative to muscle onset in a cue-guided task. r Plastic changes in excitability are only observed when stimuli are delivered immediately before the time when muscles activate, while stimuli delivered at muscle onset or shortly later (0, +50 ms) have no effect. r Plastic effects are abolished if there is ongoing volitional electromyogram activity in the muscles prior to the onset of the phasic contraction. r The plastic effects induced by timing peripheral stimulation relative to electromyographic markers of muscle activation are as effective as those that occur if stimulation is timed relative to electroencephalographic markers of motor cortical activation. We provide a simple alternative protocol to induce plasticity in people in whom electroencephalogram recording is difficult.

SICI during changing brain states: Differences in methodology can lead to different conclusions

“…Sessions began with wSRTT familiarization, followed by 20 additional trials used to estimate the participants’ RT, defined as the average time when the rectified and smoothed (5 ms sliding windows) EMG exceeded five times the amplitude at rest [ 10 ]. We then measured RMT and the three TS intensities ( 1mV REST , 1mV WS and 1 mV 200 ms ).…”

Plasticity induced by pairing brain stimulation with motor-related states only targets a subset of cortical neurones

“…TMS pulses were delivered before muscle activation in 95 ± 22% and 93 ± 25% of the trials in the PA and AP interventions. This anticipatory feature of stimuli has proven to be important to ensure induction of plastic effects in these interventions [3]. rMT and 500T with PA currents were 49 ± 9% and 57 ± 9% of the maximum stimulator output.…”

“…Here we applied AP or PA TMS pulses applied just prior to the onset of volitional index finger movements in two experiments conducted on separate days in the same group of individuals [3]. Corticospinal excitability changes induced by these interventions were assessed using AP and PA TMS pulses in the effector muscle and in a control muscle.…”

“…RTs were defined as the average time when the rectified and smoothed EMG exceeded five times the amplitude at rest [3]. RTs were compared between interventions using a paired t-test.…”

Towards a mechanistic approach for the development of non‐invasive brain‐computer interfaces for motor rehabilitation

“…While some of these approaches have been proven to induce significant improvements in motor function and induction of structural plasticity (Ang et al 2010;Broetz et al 2010;Shindo et al 2011;Pichiorri et al 2011Pichiorri et al , 2015Cincotti et al 2012;Li et al 2013;Jang et al 2016), the lack of precise timing in associating specific brain states and brain stimuli has been shown to have drastic effects when dynamic brain changes (e.g. movement initiation-related states) are targeted by BCI interventions (Mrachacz-Kersting et al 2012;Mrachacz-Kersting & Aliakbaryhosseinabadi, 2018;Fu et al 2021).…”