Noninvasive and minimally invasive brain-computer interfaces for neurorehabilitation
Noninvasive brain-computer interfaces (niBCI) hold promise to revolutionize our communication with computers and other external devices by making a direct link to our thoughts represented by neural activity in various brain regions. Despite decades of research, this pledge, ubiquitously present in BCI-related grant proposals all over the world, has only been partly fulfilled. Additionally, only a few of niBCI paradigms represent genuine thought-mediated communications while many merely utilize neural responses to external stimuli. Motor imagery (MI) paradigm is unique as it enables control of an external device literally by thought. However, information transfer rate of a MI-based communication channel is quite low.
Fortunately, clinical neurorehabilitation procedures are not highly demanding with respect to information transfer rate. Therefore, the most practical applications of MI-based niBCIs are in neurorehabilitation of patients with motor and sensory deficits. Robotic systems have been already developed and tested that are driven by the upper-limb motor imagery. Yet, there has been relatively little work on the application of niBCIs to the rehabilitation of lower-limb function.
In the first part of my talk, I will describe our niBCI system for rehabilitation of patients with lower-limb paralysis. This system is based on foot motor-imagery niBCI that controls the lower-limb exoskeleton Exoatlet. Aided with our niBCI, patients generate stepping movements by simply thinking about them. This is a powerful paradigm for neurorehabilitation because it synchronizes cortically-generated motor intentions with the sensory responses evoked by exoskeleton movements. Under these conditions, the central nervous system is able to plastically modify and repair damage caused by neurological conditions. We will present a live demonstration of our system, with a paraplegic patient controlling the exoskeletons by his EEG activity.
In the second part of my talk, I will discuss how electrocorticography (ECoG), a minimally invasive recording procedure, could be used to improve the performance of neurorehabilitation neuroprostheses. To this end, we have started a research program aimed on the development of invasive BCI (iBCI) for dexterous and natural control of a variety of external devices. We have achieved a considerable progress over the last year in the development of the first Russian bidirectional electrocorticography (ECoG) based iBCI. Based on this progress, we foresee that iBCI will become a powerful method for functional restoration of neurologically disabled patients, including the ones suffering from the upper and lower-limb functional deficits and even cognitive disabilities.