Neuromodulation of Brain Rhythms to Reduce Pain after Spinal Cord Injury

This study will be conducted based on a single-case experimental design (SCED) with multiple baselines across participants. The SCED method is based on assessing the dependent variables (e.g. pain intensity) repeatedly for each of the participants across phases. The design of this study will be AB + follow-ups, where A refers to the baseline phase, B is the intervention phase, and they will be followed by two follow-up phases. Three participants will be randomly assigned to different baseline durations of the SCED. In this study, a stable baseline will be considered to be one week (i.e., 7 days of observation). The baseline for the first participant will be 7 days, the second participant will have a 10-day baseline, and the third participant will have a 14-day baseline. All participants will start the baseline phase on the same day. Each baseline phase will be followed by 20 days of 30-minute BCI-N intervention over a 4-week period. Subsequently, there will be a 1-week follow-up for each participant immediately after completion of the intervention. In addition, a further 1-week follow-up will take place 3 months after completion of the intervention. During the baseline phase, participants will administer the self-report questionnaires for the primary and secondary outcomes, and will continue reporting them during intervention and follow-up phases in order to monitor possible changes in pain intensity and pain interference. The participants will be contacted everyday to ensure they are completing their pain diaries and pain interference questionnaires in the required times. The BCI-N intervention procedure will be administered by a researcher. Each participant will receive 30-minute daily sessions of the BCI-N intervention for 20 days over a 4-week period. Each session will involve two 15-minute BCI-N intervention divided by a 5-minute break, and each session will start and finish with measurement of the resting-state EEG levels. EEG acquisition will be performed using the EEG system “SMARTING” device (mBrainTrain, Serbia). The BCI-N treatment incorporates an interactive gaming interface (i.e. “NeuroGame”), and a neuromodulation protocol targeted to suppress theta and low alpha (4-8 Hz) and high beta (20-30 Hz) band powers, and to enhance high alpha (9-12 Hz) band power. During the BCI-N intervention, neurofeedback will be performed on SCI neuropathic pain-related regions of the brain, e.g., C3 and C4. In particular, the EEG signals will be processed in real-time using custom-scripts in MATLAB (MathWorks Inc, USA) utilizing EEGLAB functions. The neuromodulation procedure during the real-time EEG processing will include extracting the power from the frequency of interest (selected frequency bands, i.e., 4-8 Hz, 9-12 Hz and 20-30 Hz) and transferring the information to the NeuroGame interface. The NeuroGame interface was developed using the Unity3D game engine (Unity Technologies, USA). Our game scenario is based on a online game called “A Waffles Fate”. We modified the concept from a navigating “ghost” to a “jellyfish”. Our scenario, called “Floating Jellyfish”, provides neurofeedback in an interactive, goal-directed gaming environment. The visual feedback of the “Floating Jellyfish” game scenario is as follows: When only one EEG frequency band power is suppressed or reinforced as desired, the jellyfish changes colour; when two frequency band powers are activated correctly, the jellyfish starts to move; and when all three band powers are activated, the ocean background changes colour, and a seconds timer begins. Points accumulate only for those seconds that the participant keeps all three bands activated. The aim of the game is to receive as many points as possible.