Evidence for language-specificity of a BCI-based language training
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1
Universitätsklinikum Freiburg, Neurology, Germany
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2
Brain State Decoding Lab, Germany
Introduction: Language therapy for aphasia following stroke generally focuses on patients’ specific language deficits and is guided and controlled by an external person, e.g. by the speech therapist or a trained volunteer [1]. In contrast, closed-loop approaches based on brain-computer interfaces (BCI) have been used successfully for motor impairments after stroke [2] and are guided and controlled by the patients themselves. This study aimed at investigating if a BCI-based approach can also be designed for language training to patients with aphasia. For the first time, we developed and implemented a BCI-based training protocol for chronic aphasia patients after stroke. After attending word stimuli, patients receive feedback based on the strength of task-relevant EEG signals. Feasibility of the protocol was previously evaluated in an offline study with 20 normally-aged controls.
Material and Methods: Eight patients with an infarct in the left middle cerebral artery and chronic aphasia underwent about 30 hours of effective BCI-supported online training. During each training session, patients were seated in a ring of 6 loudspeakers (AMUSE paradigm, [3]) and brain signals were measured by EEG (32 channel passive Ag/AgCl electrodes). Patients heard a cueing sentence followed by a series of 6 bisyllabic words (concrete nouns) from which one correctly finished the sentence. After each trial, they received a feedback on whether the attended word predicted by event-related potentials (ERP) responses matched the target word.
Before and after the training, all patients underwent an aphasia test battery for language assessment (Aachener Aphasie Test (AAT) [4] and Snodgrass naming test) as well as tests for executive functions (TAP, Corsi, digit span and word-fluency test). Two EEG-sessions (64 EEG channels) without feedback were conducted prior to the training to calibrate the BCI system and to determine parameters of the training protocol (e.g. the stimulation onset asynchrony between two words) for each patient. In addition, one session without feedback was recorded after the training to compare ERP responses.
Results: The AAT showed a significant improvement of several subtests such as naming, writing, comprehension and the token subtest. Similarly, the naming performance in the Snodgrass & Vanderwart test also significantly increased. TAP, Corsi, digit span and word-fluency revealed deficits in executive functions in each patient prior to the training. Contrary to the language-related tests, we did not observe any significant improvements in these neuropsychological categories. Further evidence for the language-specificity of the training can be derived from the ERP analysis where word ERP responses showed an increase in amplitude of the P300 and N200 component and a decrease in P300 onset latency whereas the ERP results to tone stimuli did not show significant training-induced changes.
Discussion & Conclusion: Our preliminary results showed that our BCI-supported aphasia training was very effective for the recovery of language deficits with an effect that generalizes to language aspects that had not been trained directly (such as writing or reading). This novel therapeutic approach did not train executive functions, but more directly distinct aspects of language-processing.
Acknowledgements
Acknowledgements: This work was (partly) supported by BrainLinks-BrainTools, Cluster of Excellence funded by the German Research Foundation (DFG), grant number EXC 1086 and by Wissenschaftliche Gesellschaft Freiburg im Breisgau.
References
References
[1] M.C. Brady, H. Kelly, J. Godwin, P. Enderby, P. Campbell, Cochrane Database Syst. Rev. (2016) CD000425.
[2] A. Remsik, B. Young, R. Vermilyea, L. Kiekhoefer, J. Abrams, S. Evander Elmore, P. Schultz, V. Nair, D. Edwards, J. Williams, V. Prabhakaran, Expert Rev. Med. Devices 13 (2016) 445–454.
[3] M. Schreuder, B. Blankertz, M. Tangermann, PLoS One 5 (2010) e9813.
[4] W. Huber, Aachener Aphasie-Test:(AAT), Hogrefe, Verlag für Psychologie, 1983.
Keywords:
Speech Therapy,
Speech Processing,
music processing,
Executive Function,
Stroke
Conference:
Academy of Aphasia 56th Annual Meeting, Montreal, Canada, 21 Oct - 23 Oct, 2018.
Presentation Type:
oral presentation
Topic:
not eligible for a student prize
Citation:
Musso
M,
Hübner
D,
Schwarzkopf
S,
Weiller
C and
Tangermann
M
(2019). Evidence for language-specificity of a BCI-based language training.
Conference Abstract:
Academy of Aphasia 56th Annual Meeting.
doi: 10.3389/conf.fnhum.2018.228.00069
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Received:
05 Apr 2018;
Published Online:
22 Jan 2019.
*
Correspondence:
Dr. Mariacristina Musso, Universitätsklinikum Freiburg, Neurology, Freiburg, Germany, mariachristina.musso@uniklinik-freiburg.de