Non-invasive brain-spine interface: Continuous control of trans-spinal magnetic stimulation using EEG

Modulatory effect of trans-spinal magnetic intermittent theta burst stimulation on diaphragmatic activity following cervical spinal cord contusion in the rat

BACKGROUND CONTEXT

Magnetic stimulation can noninvasively modulate the neuronal excitability through different stimulatory patterns.

PURPOSE

The present study hypothesized that trans-spinal magnetic stimulation with intermittent theta burst stimulatory pattern can modulate respiratory motor outputs in a pre-clinical rat model of cervical spinal cord injury.

STUDY DESIGN

In vivo animal study.

METHODS

The effect of trans-spinal magnetic intermittent theta burst stimulation on diaphragmatic activity was assessed in adult rats with unilateral cervical spinal cord contusion at 2 weeks postinjury.

RESULTS

The results demonstrated that unilateral cervical spinal cord contusion significantly attenuated the inspiratory activity and motor evoked potential of the diaphragm. Trans-spinal magnetic intermittent theta burst stimulation significantly increased the inspiratory activity of the diaphragm in cervical spinal cord contused rats. Inspiratory bursting was also recruited by trans-spinal magnetic intermittent theta burst stimulation in the rats without diaphragmatic activity after cervical spinal cord injury. In addition, trans-spinal magnetic intermittent theta burst stimulation is associated with increases in oxygen consumption and carbon dioxide production.

CONCLUSIONS

These results suggest that trans-spinal magnetic intermittent theta burst stimulation can induce respiratory neuroplasticity.

CLINICAL SIGNIFICANCE

We propose that trans-spinal theta burst magnetic stimulation may be considered a potential rehabilitative strategy for improving the respiratory activity after cervical spinal cord injury. This will require future clinical study.

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

Background

The mirror neuron system (MNS) plays a key role in the neural mechanism underlying motor learning and neural plasticity. Action observation (AO), action execution (AE), and a combination of both, known as action imitation (AI), are the most commonly used rehabilitation strategies based on MNS. It is possible to enhance the cortical activation area and amplitude by combining traditional neuromuscular electrical stimulation (NMES) with other top-down and active rehabilitation strategies based on the MNS theory.

Objective

This study aimed to explore the cortical activation patterns induced by NMES synchronized with rehabilitation strategies based on MNS, namely NMES+AO, NMES+AE, and NMES+AI. In addition, the study aimed to assess the feasibility of these three novel rehabilitative treatments in order to provide insights and evidence for the design, implementation, and application of brain-computer interfaces.

Methods

A total of 70 healthy adults were recruited from July 2022 to February 2023, and 66 of them were finally included in the analysis. The cortical activation patterns during NMES+AO, NMES+AE, and NMES+AI were detected using the functional Near-Infrared Spectroscopy (fNIRS) technique. The action to be observed, executed, or imitated was right wrist and hand extension, and two square-shaped NMES electrodes were placed on the right extensor digitorum communis. A block design was adopted to evaluate the activation intensity of the left MNS brain regions.

Results

General linear model results showed that compared with the control condition, the number of channels significantly activated (PFDR < 0.05) in the NMES+AO, NMES+AE, and NMES+AI conditions were 3, 9, and 9, respectively. Region of interest (ROI) analysis showed that 2 ROIs were significantly activated (PFDR < 0.05) in the NMES+AO condition, including BA6 and BA44; 5 ROIs were significantly activated in the NMES+AE condition, including BA6, BA40, BA44, BA45, and BA46; and 6 ROIs were significantly activated in the NMES+AI condition, including BA6, BA7, BA40, BA44, BA45, and BA46.

Conclusion

The MNS was activated during neuromuscular electrical stimulation combined with an AO, AE, and AI intervention. The synchronous application of NMES and mirror neuron rehabilitation strategies is feasible in clinical rehabilitation. The fNIRS signal patterns observed in this study could be used to develop brain-computer interface and neurofeedback therapy rehabilitation devices.