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Jan 22, 2007

BCI: Communication and Restoration of Movement in Paralysis

Brain-Computer-Interfaces(BCI): Communication and Restoration of Movement in Paralysis.

J Physiol. 2007 Jan 18;

Authors: Birbaumer N, Cohen LG

The review describes the status of brain-computer- or brain-machine-interface research. We focus on non-invasive brain-computer-interfaces (BCIs) and their clinical utility for direct brain communication in paralysis and motor restoration in stroke. A large gap between the promises of invasive animal and invasive human BCI-preparations and the clinical reality characterises the literature: while intact monkeys learn to execute more or less complex upper limb movements with spike patterns from motor brain regions alone without concomitant peripheral motor activity usually after extensive training, clinical applications in human diseases such as Amyotrophic Lateral Sclerosis and Paralysis from stroke or spinal cord lesions shows only limited success with the exception of verbal communication in paralysed and locked-in patients: BCIs based on electroencephalographic potentials or oscillations are ready to undergo large clinical studies and commercial production as an adjunct or a major assisted communication device for paralysed and locked-in patients. However, attempts to train completely locked-in patients with BCI-communication after entering the complete locked-in state with no remaining eye-movement failed. We propose that a lack of contingencies between goal directed thoughts and intentions may be at the heart of this problem. Experiments with chronically curarised rats support our hypothesis, operant conditioning and voluntary control of autonomic physiological functions turned out to be impossible in this preparation. In addition to assisted communication BCIs consisting of operant learning of EEG slow cortical potentials and sensorimotor rhythm was demonstrated to be successful in drug resistant focal epilepsy and attention deficit disorder. First studies of non-invasive BCIs using sensorimotor rhythm of the EEG and MEG in restoration of paralysed hand movements in chronic stroke and single cases of high spinal cord lesions show some promise but need extensive evaluation in well-controlled experiments. Invasive BMIs based on neuronal spike patterns, local field potentials or electrocorticogram may constitute the strategy of choice in severe cases of stroke and spinal cord paralysis. Future directions of BCI research should include the regulation of brain metabolism and blood flow and electrical and magnetic stimulation of the human brain (invasive and non-invasive). A series of studies using BOLD-response regulation with functional magnetic resonance imaging (fMRI) and near infrared spectroscopy demonstrated a tight correlation between voluntary changes in brain metabolism and behaviour.

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