Communication and Control by Listening: Toward Optimal Design of a Two-Class Auditory Streaming Brain-Computer Interface

N Jeremy Hill,Stephan Kienzle,Aisha Moinuddin,Gerwin Schalk,Ann-Katrin Häuser

doi:10.3389/fnins.2012.00181

Abstract

Most brain-computer interface (BCI) systems require users to modulate brain signals in response to visual stimuli. Thus, they may not be useful to people with limited vision, such as those with severe paralysis. One important approach for overcoming this issue is auditory streaming, an approach whereby a BCI system is driven by shifts of attention between two simultaneously presented auditory stimulus streams. Motivated by the long-term goal of translating such a system into a reliable, simple yes-no interface for clinical usage, we aim to answer two main questions. First, we asked which of two previously published variants provides superior performance: a fixed-phase (FP) design in which the streams have equal period and opposite phase, or a drifting-phase (DP) design where the periods are unequal. We found FP to be superior to DP (p = 0.002): average performance levels were 80 and 72% correct, respectively. We were also able to show, in a pilot with one subject, that auditory streaming can support continuous control and neurofeedback applications: by shifting attention between ongoing left and right auditory streams, the subject was able to control the position of a paddle in a computer game. Second, we examined whether the system is dependent on eye movements, since it is known that eye movements and auditory attention may influence each other, and any dependence on the ability to move one’s eyes would be a barrier to translation to paralyzed users. We discovered that, despite instructions, some subjects did make eye movements that were indicative of the direction of attention. However, there was no correlation, across subjects, between the reliability of the eye movement signal and the reliability of the BCI system, indicating that our system was configured to work independently of eye movement. Together, these findings are an encouraging step forward toward BCIs that provide practical communication and control options for the most severely paralyzed users.

Highlights

Brain-computer interfaces (BCI) are a topic of research and development that has seen increasing interest in the last 20–30 years
One of the most commonly considered goals is the development of communication systems for people who are locked-in by a paralyzing disease or accident (Bauer et al, 1979; Kübler and Birbaumer, 2008) – an example of replacement of an important function normally served by the motor system
We examine a two-class auditory streaming BCI system based on eventrelated potentials (ERPs)

Summary

Introduction

Brain-computer interfaces (BCI) are a topic of research and development that has seen increasing interest in the last 20–30 years (see Wolpaw et al, 2002; Wolpaw and Wolpaw, 2012, for review). One of the most commonly considered goals is the development of communication systems for people who are locked-in by a paralyzing disease or accident (Bauer et al, 1979; Kübler and Birbaumer, 2008) – an example of replacement of an important function normally served by the motor system. Within this field, there has been a recent increase in interest in BCI systems that are based on purely non-visual input. This is motivated by the desire to reach users in the most severely paralyzed states, for whom spatial vision may become extremely limited by the inability to open, direct, or focus the eyes voluntarily, by the inability to make saccades to integrate multiple fixations into a www.frontiersin.org

Objectives

Methods

Results

Conclusion