Brain-Computer Interface-Based Communication in the Completely Locked-In State

PLoS Biol. 2017 Jan 31;15(1):e1002593. doi: 10.1371/journal.pbio.1002593. eCollection 2017 Jan.


Despite partial success, communication has remained impossible for persons suffering from complete motor paralysis but intact cognitive and emotional processing, a state called complete locked-in state (CLIS). Based on a motor learning theoretical context and on the failure of neuroelectric brain-computer interface (BCI) communication attempts in CLIS, we here report BCI communication using functional near-infrared spectroscopy (fNIRS) and an implicit attentional processing procedure. Four patients suffering from advanced amyotrophic lateral sclerosis (ALS)-two of them in permanent CLIS and two entering the CLIS without reliable means of communication-learned to answer personal questions with known answers and open questions all requiring a "yes" or "no" thought using frontocentral oxygenation changes measured with fNIRS. Three patients completed more than 46 sessions spread over several weeks, and one patient (patient W) completed 20 sessions. Online fNIRS classification of personal questions with known answers and open questions using linear support vector machine (SVM) resulted in an above-chance-level correct response rate over 70%. Electroencephalographic oscillations and electrooculographic signals did not exceed the chance-level threshold for correct communication despite occasional differences between the physiological signals representing a "yes" or "no" response. However, electroencephalogram (EEG) changes in the theta-frequency band correlated with inferior communication performance, probably because of decreased vigilance and attention. If replicated with ALS patients in CLIS, these positive results could indicate the first step towards abolition of complete locked-in states, at least for ALS.

Publication types

  • Research Support, N.I.H., Intramural
  • Research Support, Non-U.S. Gov't
  • Retracted Publication

MeSH terms

  • Brain-Computer Interfaces*
  • Communication*
  • Electroencephalography
  • Humans
  • Oxyhemoglobins / metabolism
  • Quadriplegia / physiopathology*
  • ROC Curve
  • Signal Processing, Computer-Assisted
  • Spectroscopy, Near-Infrared


  • Oxyhemoglobins

Grant support

The work was funded by grants from the following: Deutsche Forschungsgemeinschaft (DFG, Bi195, Kosellek,, which supported NB, UC, and BX; Stiftung Volkswagenwerk (VW,, which supported NB; German Ministry of Education and Research (BMBF grant No.: MOTOR-BIC (FKZ 136W0053,, which supported NB; Baden-Württemberg Stiftung, EMOIO from the Federal Ministry of Education and Research (524-4013-16SV7196,, which supported NB; Eva and Horst Köhler-Stiftung, (Berlin,, which supported NB; National Natural Science Foundation of China (Grant number: 61550110252,, which supported UC; and EU grant LUMINOUS (Grant number: 686764,, which supported NB and UC. SS was supported by regular salary from San Camillo hospital in Venice, Italy. LG was supported by the intramural research program of the NINDS, NIH. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.