It takes two (seconds): decreasing encoding time for two-choice functional near-infrared spectroscopy brain–computer interface communication

Anna Vorreuther; Lisa Bastian; Amaia Benitez Andonegui; Danielle Evenblij; Lars Riecke; Michael Lührs; Bettina Sorger

doi:10.1117/1.NPh.10.4.045005

2 November 2023 It takes two (seconds): decreasing encoding time for two-choice functional near-infrared spectroscopy brain–computer interface communication

Anna Vorreuther, Lisa Bastian, Amaia Benitez Andonegui, Danielle Evenblij, Lars Riecke, Michael Lührs, Bettina Sorger

Author Affiliations +

Neurophotonics, Vol. 10, Issue 4, 045005 (November 2023). https://doi.org/10.1117/1.NPh.10.4.045005

Abstract

Significance

Brain–computer interfaces (BCIs) can provide severely motor-impaired patients with a motor-independent communication channel. Functional near-infrared spectroscopy (fNIRS) constitutes a promising BCI-input modality given its high mobility, safety, user comfort, cost-efficiency, and relatively low motion sensitivity.

Aim

The present study aimed at developing an efficient and convenient two-choice fNIRS communication BCI by implementing a relatively short encoding time (2 s), considerably increasing communication speed, and decreasing the cognitive load of BCI users.

Approach

To encode binary answers to 10 biographical questions, 10 healthy adults repeatedly performed a combined motor-speech imagery task within 2 different time windows guided by auditory instructions. Each answer-encoding run consisted of 10 trials. Answers were decoded during the ongoing experiment from the time course of the individually identified most-informative fNIRS channel-by-chromophore combination.

Results

The answers of participants were decoded online with an accuracy of 85.8% (run-based group mean). Post-hoc analysis yielded an average single-trial accuracy of 68.1%. Analysis of the effect of number of trial repetitions showed that the best information-transfer rate could be obtained by combining four encoding trials.

Conclusions

The study demonstrates that an encoding time as short as 2 s can enable immediate, efficient, and convenient fNIRS-BCI communication.

CC BY: © The Authors. Published by SPIE under a Creative Commons Attribution 4.0 International License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Anna Vorreuther, Lisa Bastian, Amaia Benitez Andonegui, Danielle Evenblij, Lars Riecke, Michael Lührs, and Bettina Sorger "It takes two (seconds): decreasing encoding time for two-choice functional near-infrared spectroscopy brain–computer interface communication," Neurophotonics 10(4), 045005 (2 November 2023). https://doi.org/10.1117/1.NPh.10.4.045005

Received: 15 April 2023; Accepted: 18 August 2023; Published: 2 November 2023

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