A comparison of two spelling Brain-Computer Interfaces based on visual P3 and SSVEP in Locked-In Syndrome.

Adrien Combaz,Steven Laureys,Gertie Vanhoof,Vincent Thijs,Camille Chatelle,Ann Goeleven,Marc M Van Hulle,Arne Robben

doi:10.1371/journal.pone.0073691

Adrien Combaz, Steven Laureys + Show 6 more

Open Access

https://doi.org/10.1371/journal.pone.0073691

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Journal: PloS one	Publication Date: Sep 25, 2013
Citations: 110	License type: CC BY 4.0

Affiliation: KU Leuven, University of Liège

Abstract

ObjectivesWe study the applicability of a visual P3-based and a Steady State Visually Evoked Potentials (SSVEP)-based Brain-Computer Interfaces (BCIs) for mental text spelling on a cohort of patients with incomplete Locked-In Syndrome (LIS).MethodsSeven patients performed repeated sessions with each BCI. We assessed BCI performance, mental workload and overall satisfaction for both systems. We also investigated the effect of the quality of life and level of motor impairment on the performance.ResultsAll seven patients were able to achieve an accuracy of 70% or more with the SSVEP-based BCI, compared to 3 patients with the P3-based BCI, showing a better performance with the SSVEP BCI than with the P3 BCI in the studied cohort. Moreover, the better performance of the SSVEP-based BCI was accompanied by a lower mental workload and a higher overall satisfaction. No relationship was found between BCI performance and level of motor impairment or quality of life.ConclusionOur results show a better usability of the SSVEP-based BCI than the P3-based one for the sessions performed by the tested population of locked-in patients with respect to all the criteria considered. The study shows the advantage of developing alternative BCIs with respect to the traditional matrix-based P3 speller using different designs and signal modalities such as SSVEPs to build a faster, more accurate, less mentally demanding and more satisfying BCI by testing both types of BCIs on a convenience sample of LIS patients.

Highlights

A Brain-Computer Interface (BCI) is a system aiming at establishing a non-muscular communication pathway between the brain and a computer [1]
BCIs could be of interest for establishing a functional communication code for patients whose motor output channels are severely impaired typically caused by an acute ventro-pontine brainstem lesion, or in the end stage of amyotrophic lateral sclerosis (ALS; [3,4]) and for whom devices that rely on residual voluntary motor activity are not effective [5]
All patients were able to reach an accuracy above 70% with the State Visually Evoked Potentials (SSVEP) system; this was not the case for the P3 system as patients S1, S5, S6 and S7 failed to overcome this threshold, regardless of the settings used

Summary

Introduction

A Brain-Computer Interface (BCI) is a system aiming at establishing a non-muscular communication pathway between the brain and a computer [1]. BCIs could be of interest for establishing a functional communication code for patients whose motor output channels are severely impaired (in most severe cases, patients with Locked-In Syndrome – LIS) typically caused by an acute ventro-pontine brainstem lesion (commonly after stroke or more rarely after traumatic brain injury; [2]), or in the end stage of amyotrophic lateral sclerosis (ALS; [3,4]) and for whom devices that rely on residual voluntary motor activity are not effective [5]. We prefer to use the more usual term P3-based BCI (no electrodes were placed over the occipital region in our study for this type of BCI)

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