Influence of spontaneous rhythm on movement-related cortical potential: a preliminary neurofeedback study

We have recently developed an associative Brain-Computer Interface (BCI) for neuromodulation in chronic and acute stroke patients that leads to functional improvements. The control signal is the movement related cortical potential (MRCP) that develops prior to movement execution. The MRCP increases in variability as a novel task is learned, which in turn significantly decreases the detection accuracy. In the current study we sought to investigate if tactile stimulation, often implemented in rehabilitation, may act as a primer to our associative BCI by decreasing MRCP variability. Six chronic stroke patients were exposed to one session of tactile stimulation, and the MRCP of an arm lifting task, repeated 30 times, extracted. Results reveal that for three patients the MRCP detection accuracy expressed as the rate of true and false positives was improved. In two patients however the detection accuracy declined while one patient was unable to complete the experiment. Since tactile stimulation is a common tool implemented by physiotherapists to train patients to perform dynamic movements with the appropriate muscle pattern to avoid compensatory actions by other muscles it will be important to decipher why it results in such differential effects across patients.