Rapid P300 brain-computer interface communication with a head-mounted display.

Andrea Kübler,Sebastian Halder,Ivo Käthner

doi:10.3389/fnins.2015.00207

Abstract

Visual ERP (P300) based brain-computer interfaces (BCIs) allow for fast and reliable spelling and are intended as a muscle-independent communication channel for people with severe paralysis. However, they require the presentation of visual stimuli in the field of view of the user. A head-mounted display could allow convenient presentation of visual stimuli in situations, where mounting a conventional monitor might be difficult or not feasible (e.g., at a patient's bedside). To explore if similar accuracies can be achieved with a virtual reality (VR) headset compared to a conventional flat screen monitor, we conducted an experiment with 18 healthy participants. We also evaluated it with a person in the locked-in state (LIS) to verify that usage of the headset is possible for a severely paralyzed person. Healthy participants performed online spelling with three different display methods. In one condition a 5 × 5 letter matrix was presented on a conventional 22 inch TFT monitor. Two configurations of the VR headset were tested. In the first (glasses A), the same 5 × 5 matrix filled the field of view of the user. In the second (glasses B), single letters of the matrix filled the field of view of the user. The participant in the LIS tested the VR headset on three different occasions (glasses A condition only). For healthy participants, average online spelling accuracies were 94% (15.5 bits/min) using three flash sequences for spelling with the monitor and glasses A and 96% (16.2 bits/min) with glasses B. In one session, the participant in the LIS reached an online spelling accuracy of 100% (10 bits/min) using the glasses A condition. We also demonstrated that spelling with one flash sequence is possible with the VR headset for healthy users (mean: 32.1 bits/min, maximum reached by one user: 71.89 bits/min at 100% accuracy). We conclude that the VR headset allows for rapid P300 BCI communication in healthy users and may be a suitable display option for severely paralyzed persons.

Highlights

Brain-computer interfaces (BCIs) can serve as muscle-independent communication channel through the use of brain signals as control commands for output devices
Performance of Healthy Users It could be shown that the average accuracies achieved during online spelling by the healthy participants did not differ for the virtual reality (VR) headset and a conventional 22” TFT monitor
Healthy users achieved very high spelling accuracies (>90%) with a VR headset, similar to those achieved with a conventional monitor used to display a P300 BCI matrix

Summary

Introduction

Brain-computer interfaces (BCIs) can serve as muscle-independent communication channel through the use of brain signals as control commands for output devices. Event related potentials (ERPs) extracted from the electroencephalogram (EEG) are commonly utilized as control signals (see Kleih et al, 2011; Mak et al, 2011 for reviews). It consists of a symbol matrix that is presented to the BCI users on a computer screen. The most prominent ERP that is elicited by this method is the P300. It is a positive voltage deflection in the EEG that peaks at about 250–500 ms after onset of a rare, but task relevant stimulus (Polich, 2007). Varying degrees of motor impairments and the different paradigms used yielded a wide range of accuracies (see review by Mak et al, 2011)

Methods

Results

Discussion

Conclusion