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SYMPOSIUM REPORT |
1 Institute of Medical Psychology and Behavioural Neurobiology, University of Tuebingen, Tuebingen, Germany
2 National Institutes of Health, NINDS, Human Cortical Physiology Section, Bethesda, MD, USA
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 human BCI preparations and the clinical reality characterizes 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 show 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 curarized 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 were 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.
(Received 27 November 2006;
accepted after revision 12 January 2007;
first published online 18 January 2007)
Corresponding author N. Birbaumer: Institute of Medical Psychology and Behavioural Neurobiology, University of Tuebingen, Tuebingen, Germany. Email: niels.birbaumer{at}uni-tuebingen.de
This article has been cited by other articles:
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  E. Buch, C. Weber, L. G. Cohen, C. Braun, M. A. Dimyan, T. Ard, J. Mellinger, A. Caria, S. Soekadar, A. Fourkas, et al. Think to Move: a Neuromagnetic Brain-Computer Interface (BCI) System for Chronic Stroke Stroke, March 1, 2008; 39(3): 910 - 917. [Abstract] [Full Text] [PDF]
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 L. G. Cohen and N. Birbaumer The physiology of brain-computer interfaces J. Physiol., March 15, 2007; 579(3): 570 - 570. [Full Text] [PDF]
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E. E. Fetz Volitional control of neural activity: implications for brain-computer interfaces J. Physiol., March 15, 2007; 579(3): 571 - 579. [Abstract] [Full Text] [PDF]
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