A Novel Brain-Computer Interface for Chronic Stroke Patients
We present a novel brain-computer interface for neuromodulation that leads to long lasting cortical plasticity. The system entails in recording the movement-related cortical potential (MRCP) as a subject imagines a dorsiflexion task and triggering an elec
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Center for Sensory-Motor Interaction, Department of Health Science and Technology, Aalborg University, DK-9220 Aalborg, Denmark 2 Strategic Technology Management, Otto Bock HealthCare GmbH, Duderstadt, Germany 3 Neurorehabilitation Engineering Bernstein Center for Computational Neuroscience University Medical Center, Göttingen, Germany [email protected]
Abstract. We present a novel brain-computer interface for neuromodulation that leads to long lasting cortical plasticity. The system entails in recording the movement-related cortical potential (MRCP) as a subject imagines a dorsiflexion task and triggering an electrical stimulator to generate a single stimulus to the target nerve. This system has been tested on healthy subjects to demonstrate that an artificially generated signal (the peripheral afferent volley) can interact with a physiologically generated signal (the MRCP) in humans, leading to plastic changes. Further, in a group of 13 chronic stroke patients, the intervention also induced functional improvements within only three sessions. In this chapter, we outline the protocol in detail and discuss the potential for artificially inducing cortical plasticity in patients (neuromodulation). In these applications, the intention to move can be detected without a cue directly from the EEG traces. We have commenced to identify force and speed characteristics from single MRCPs, and our pilot data reveals that, if the nerve stimulation characteristics match the imagined movement, plasticity is further enhanced. Keywords: Hebbian Plasticity, movement related cortical potentials, peripheral nerve stimulation, brain computer interface, stroke.
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Introduction
Stroke rehabilitation therapy for motor functions aims to activate and reorganize the brain areas related to the planning and execution of voluntary movements. Numerous novel rehabilitation techniques based on non-invasive brain stimulation have been proposed and can lead to functional improvements in the chronic phase following the insult (1,2). Typically, their effects are quantified by assessing the transmission change in the corticospinal tract using transcranial magnetic stimulation (TMS). However, recent evidence suggests that those cortical areas related to movement planning, sensorimotor processing, attention and task complexity contribute to a similar extend in stroke survivors and controls (3). This indicates that they are largely left intact, though their output is not conveyed to allow appropriate functionality. While C. Guger, B. Allison, and E.C. Leuthardt (eds.), Brain-Computer Interface Research, Biosystems & Biorobotics 6, DOI: 10.1007/978-3-642-54707-2_6, © Springer-Verlag Berlin Heidelberg 2014
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the non-invasive cortical stimulation approaches show improvements in performance, stimulation of the cortex with techniques such as repetitive TMS or transcranial direct current stimulation (tDCS) have limitations due to current spread to adjacent nontargeted areas. They may thus activate intact areas inappropriately
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