Cortical activation of neuromuscular electrical stimulation synchronized mirror neuron rehabilitation strategies: an fNIRS study

Advances in brain-computer interface controlled functional electrical stimulation for upper limb recovery after stroke

Stroke often results in varying degrees of functional impairment, significantly affecting patients' quality of daily life. In recent years, brain-computer interface-controlled functional electrical stimulation has offered new therapeutic approaches for post-stroke rehabilitation. This paper reviews the application of BCI-FES in the recovery of upper limb function after stroke and explores its underlying mechanisms. By analyzing relevant studies, the aim is to provide a theoretical basis for rehabilitating upper limb function post-stroke, promote BCI-FES, and offer guidance for future clinical practice.

Effects and mechanisms of synchronous virtual reality action observation and electrical stimulation on upper extremity motor function and activities of daily living in patients with stroke: a protocol for a randomized controlled trial

Background

Existing rehabilitation techniques are not satisfactory in improving motor function after stroke, resulting in heavy social burdens. With discovery of mirror neuron system (MNS), action observation (AO) has become a promising strategy to promote motor learning in rehabilitation. Based on MNS theory and virtual reality (VR) technology, we designed an innovative rehabilitative approach: synchronous 360° VR video AO (VRAO) and neuromuscular electrical stimulation (NMES). We hypothesized that VRAO+NMES could enhance MNS activation, thus to improve upper limb motor function and activities of daily living in stroke survivors.

Methods

To explore the efficacy and mechanism of VRAO+NMES, we designed this single center, evaluator blinded, prospective, two arm parallel group randomized controlled trial with 1:1 allocation ratio. The experiment group will receive VRAO+NMES, while the control group will receive VR landscape observation combined with NMES. The Fugl-Meyer Assessment for Upper Extremity is the primary outcome of this study, Brunstrom Recovery Stages for Upper Extremity, Manual Muscle Test, Range of Motion, Modified Barthel Index, and Functional Independence Measure are the secondary outcomes. In addition, functional near-infrared spectroscopy (fNIRS) and surface electromyography (sEMG) will be used to evaluate the activation of MNS brain regions and related muscles, respectively.

Discussion

Applying VR in AO therapy (AOT) has become popular, another study direction to improve AOT is to combine it with peripheral stimulations simultaneously. Due to its full immersive characteristic and multi-sensory input, 360° videos based VRAO+NMES could improve the motivation and engagement level of participants. In addition, fNIRS and sEMG test results may act as good biomarkers to predict rehabilitation outcomes, helping select suitable candidates for this new intervention.

Conclusion

The results of this study will provide evidence for the feasibility and potential clinical efficacy of VRAO+NMES in stroke rehabilitation, thus to promote the clinical applicability and generalize its use in hospital, community, and home rehabilitation settings.

Clinical trial registration

https://www.chictr.org.cn/showproj.html?proj=178276, Identifier [ChiCTR2200063552].

Effects of Electrical Stimulation on Activation of Mirror Neuron Network in Healthy Adults during Motor Execution and Imitation: An fNIRS Study

BACKGROUND

Observation, execution, and imitation of target actions based on mirror neuron network (MNN) have become common physiotherapy strategies. Electrical stimulation (ES) is a common intervention to improve muscle strength and motor control in rehabilitation treatments. It is possible to enhance MNN's activation by combining motor execution (ME) and motor imitation (MI) with ES simultaneously. This study aims to reveal whether ES could impact cortical activation during ME and MI.

METHODS

We recruited healthy individuals and assigned them randomly to the control group (CG) or experiment group (EG). Participants in EG performed ME and MI tasks with ES, while participants in CG performed the same two tasks with sham ES. We utilized functional near-infrared spectroscopy (fNIRS) to detect brain activation of MNN during ME and MI with and without ES, a randomized block design experiment paradigm was designed. Descriptive analysis of oxy-hemoglobin (HbO) and deoxy-hemoglobin (HbR) were used to show the hemoglobin (Hb) concentration changes after different event onsets in both CG and EG, a linear mixed-effects model (LMM) of HbO data was employed to analyze the effect of ES on the activation of MNN.

RESULTS

A total of 102 healthy adults were recruited and 72 participants' data were analysed in the final report. The block averaged Hb data showed that HbO concentration increased and HbR concentration decreased in most MNN regions during ME and MI in both groups. The LMM results showed that ES can significantly improve the activation of inferior frontal gyrus, middle frontal gyrus, and precentral gyrus during MI, the supplementary motor area, inferior parietal lobule, and superior temporal gyri showed increased activation, but without statistical significance. Although the results did not reach statistical significance during ME, ES still showed positive effects on increased overall activations.

CONCLUSIONS

In this study, we present potential novel rehabilitation approaches that combines MNN strategies and low-frequency ES to enhance cortical activation. Our results revealed that ES has potential to increase activation of most MNN brain areas, providing evidence for related rehabilitative interventions and device development.

CLINICAL TRIAL REGISTRATION

This study was registered on the China Clinical Trial Registration Center (identifier: ChiCTR2200064082, registered 26, September 2022, https://www.chictr.org.cn/showproj.html?proj=178285).

Attentional state-synchronous peripheral electrical stimulation during action observation induced distinct modulation of corticospinal plasticity after stroke

Introduction

Brain computer interface-based action observation (BCI-AO) is a promising technique in detecting the user's cortical state of visual attention and providing feedback to assist rehabilitation. Peripheral nerve electrical stimulation (PES) is a conventional method used to enhance outcomes in upper extremity function by increasing activation in the motor cortex. In this study, we examined the effects of different pairings of peripheral nerve electrical stimulation (PES) during BCI-AO tasks and their impact on corticospinal plasticity.

Materials and methods

Our innovative BCI-AO interventions decoded user's attentive watching during task completion. This process involved providing rewarding visual cues while simultaneously activating afferent pathways through PES. Fifteen stroke patients were included in the analysis. All patients underwent a 15 min BCI-AO program under four different experimental conditions: BCI-AO without PES, BCI-AO with continuous PES, BCI-AO with triggered PES, and BCI-AO with reverse PES application. PES was applied at the ulnar nerve of the wrist at an intensity equivalent to 120% of the sensory threshold and a frequency of 50 Hz. The experiment was conducted randomly at least 3 days apart. To assess corticospinal and peripheral nerve excitability, we compared pre and post-task (post 0, post 20 min) parameters of motor evoked potential and F waves under the four conditions in the muscle of the affected hand.

Results

The findings indicated that corticospinal excitability in the affected hemisphere was higher when PES was synchronously applied with AO training, using BCI during a state of attentive watching. In contrast, there was no effect on corticospinal activation when PES was applied continuously or in the reverse manner. This paradigm promoted corticospinal plasticity for up to 20 min after task completion. Importantly, the effect was more evident in patients over 65 years of age.

Conclusion

The results showed that task-driven corticospinal plasticity was higher when PES was applied synchronously with a highly attentive brain state during the action observation task, compared to continuous or asynchronous application. This study provides insight into how optimized BCI technologies dependent on brain state used in conjunction with other rehabilitation training could enhance treatment-induced neural plasticity.