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Brain-computer communication: Self-regulation of slow cortical potentials for verbal communication,☆☆,,★★,

Presented in part at the workshop New Trends in Human Machine Interaction: Towards Biometric-Based Action and Awareness, May 16, 2000, Espoo, Finland.
https://doi.org/10.1053/apmr.2001.26621Get rights and content

Abstract

Kübler A, Neumann N, Kaiser J, Kotchoubey B, Hinterberger T, Birbaumer NP. Brain-computer communication: self-regulation of slow cortical potentials for verbal communication. Arch Phys Med Rehabil 2001;82:1533-9. Objective: To test a training procedure designed to enable severely paralyzed patients to communicate by means of self-regulation of slow cortical potentials. Design: Application of the Thought Translation Device to evaluate the procedure in patients with late-stage amyotrophic lateral sclerosis (ALS). Setting: Training sessions in the patients' homes. Participants: Two male patients with late-stage ALS. Interventions: Patients learned voluntary control of their slow cortical potentials by means of an interface between the brain and a computer. Training was based on visual feedback of slow cortical potentials shifts and operant learning principles. The learning process was divided into small steps of increasing difficulty. Main Outcome Measures: Accuracy of self-control of slow cortical potentials (percentage of correct responses). Learning progress calculated as a function of training session. Results: Within 3 to 8 weeks, both patients learned to self-regulate their slow cortical potentials and to use this skill to select letters or words in the Language Support Program. Conclusions: This training schedule is the first to enable severely paralyzed patients to communicate without any voluntary muscle control by using self-regulation of an electroencephalogram potential only. The protocol could be a model for training patients in other brain-computer interface techniques. © 2001 by the American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation

Section snippets

Patients

Patient 1 (male; age, 45yr) was diagnosed with ALS in 1994. He had severe tetraparesis in legs and arms and lost the ability to speak by the end of 1999. He lives at home and is cared for by his family. Eye muscles are still under voluntary control. Training was conducted at the patient's home, 2 to 3 days weekly.

Patient 2 (male; age, 31yr) was diagnosed with ALS in 1998. He is almost completely paralyzed and dependent on invasive artificial ventilation via tracheostoma. He lives at home and is

Results

Figure 5 depicts representative curves for the slow cortical potentials of both patients.

. Slow cortical potentials (top panels) and vEOG curves (bottom panels) averaged across about 200 trials conducted at (A) start of training and (B) end of training. Bold lines show cortical negativity condition; thin lines, cortical positivity condition.

About 200 trials were averaged according to the task requirement. The top panel in each graph shows the course of the amplitude at the vertex referenced to A1

Discussion

The present training procedure enabled severely paralyzed patients to communicate verbally. Brain-computer communication was achieved by self-control of slow cortical potentials. The question was whether the patients could use the self-regulation skill for letter or word selection in the Language Support Program. To learn self-regulation, 2 elements are crucial: feedback of the slow cortical potential amplitude and positive reinforcement of correct behavior. It has long been shown that healthy

Conclusion

Although many varieties of brain-computer interfaces have been proposed that could be used for communication in severely paralyzed patients, no data were available on how to enable these patients to use the system. A reason for this deficit may be the enormous difficulty and additional effort required to train severely paralyzed patients in a field environment compared with the development of a system in a laboratory. The training procedure described in the present article may be a suitable way

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    Supported by the Deutsche Forschungsgemeinschaft and the Institut für Grenzgebiete in der Psychologie und Psychohygiene (Freiburg, Germany).

    ☆☆

    No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit upon the author(s) or upon any organization with which the author(s) is/are associated.

    Reprint requests to Andrea Kübler, PhD, Institute of Medical Psychology and Behavioral Neurobiology, University of Tübingen, Gartenstr 29, 72074 Tübingen, Germany, e-mail: [email protected].

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