fNIRS-BCI Neurofeedback in Stroke Rehabilitation

Objectives: 1) To compare the effects of closed-loop brain-computer interface (BCI) driven observational imitation training versus sham BCI open-loop observational imitation training on improving upper limb motor functions in patients with stroke; 2) To investigate whether stroke patients receiving closed-loop training exhibit higher activation levels in the mirror neurons, measured by event-related desynchronization (ERD), compared to those receiving open-loop training.

Hypothesis to be tested: The closed-loop training is more effective than open-loop training in improving upper limb motor outcomes, and there is an increase in the mirror neurons activity in those receiving closed-loop training.

Design and subjects: A randomized controlled trial with 44 participants with stroke.

Study instruments: Functional near-infrared spectroscopy (fNIRS)-based BCI and electroencephalography (EEG).

Interventions: In the BCI training, participants will engage in kinesthetic motor imagery. When the M1 activation level recorded by fNIRS surpasses a predefined threshold, participants will receive visual feedback to guide them to imitate the movement. However, for participants in the sham BCI group, the visual feedback will be given constantly. Both types of training consist of ten sessions.

Main outcome measures: Upper limb motor tests and the activity of mirror neurons measured by sensorimotor ERD using EEG.

Data analysis: Analysis of variance and correlation. Expected results: The closed-loop BCI-driven observational imitation training is more effective than sham BCI open-loop training on enhancing hemiplegic upper limb functions and the activation of the mirror neurons in patients after stroke.

Inclusion criteria

• unilateral upper extremity motor deficits caused by ischemic stroke, confirmed by medical documents such as discharge summary and/or neuroimaging examinations.
• chronic phase of stroke, i.e., time after stroke onset more than six months.
• aged between 18 and 75 years old.
• with mildly-to-moderately impaired upper limb functional activity that is stratified according to the levels 3-7 in the Functional Test for the Hemiplegic Upper Extremity.
• able to give informed written consent to participate in the study.
• able to read and understand traditional Chinese.

Exclusion criteria

• previous diagnosis of any neurological disease excluding ischemic stroke.
• presence of any sign of cognitive problems (The Montreal cognitive assessment Hong Kong version<22/30).
• Severe spasticity measured by the Modified Ashworth Scale score>2 in the hand, wrist or elbow extensor muscle in the hemiparetic upper extremity.
• with other notable impairments of the upper limb not caused by stroke (e.g., bone fracture in the past year, congenital deformity, or other impairments).
• current participation in any other treatment programme or clinical study involving exercise, non-invasive brain stimulation, or BCI/neurofeedback.