Abstract
People affected by severe neuro-degenerative diseases (e.g., late-stage amyotrophic lateral sclerosis (ALS) or locked-in syndrome) eventually lose all muscular control. Thus, they cannot use traditional assistive communication devices that depend on muscle control, or brain-computer interfaces (BCIs) that depend on the ability to control gaze. While auditory and tactile BCIs can provide communication to such individuals, their use typically entails an artificial mapping between the stimulus and the communication intent. This makes these BCIs diffcult to learn and use. In this study, we investigated the use of selective auditory attention to natural speech as an avenue for BCI communication. In this approach, the user communicates by directing his/her attention to one of two simultaneously presented speakers. We used electrocorticographic (ECoG) signals in the gamma band (70–170 Hz) to infer the identity of the attended speaker, thereby removing the need to learn such an artificial mapping. Our results from 12 human subjects show that a single cortical location over superior temporal gyrus or premotor cortex is typically sufficient to identify the attended speaker within 10 s and with 77% accuracy (50% accuracy due to chance). These results lay the groundwork for future studies that may determine the real-time performance of BCIs based on selective auditory attention to speech.
Highlights
Communication is an essential part of being human
While our results indicate that the presented method could support brain-computer interfaces (BCIs) communication, the reported performance metrics may have been limited by our study design and the enrolled subjects
This study confirms and extends earlier reports that showed that the envelope of an attended speech stimulus is preferentially represented in ECoG signals in the high gamma range and recorded over STG and a region of superior pre-motor cortex. We used this preferential representation of attended stimuli to identify to which speech the subjects attended when they were presented with two simultaneous speeches
Summary
Communication is an essential part of being human. It allows us to interact with each other, to establish relationships, and to express needs and desires. This fundamental human ability can become compromised in people affected by paralysis, as they are no longer able to control the muscles that allow us to gesture or speak. Conventional assistive devices (e.g., eye trackers or tongue/cheek switches) re-establish communication, but generally rely on some residual muscle control. Brain-computer interfaces (BCIs) re-establish communication by using brain signals, effectively circumventing muscular pathways [1]. BCIs still depend on perceptual modalities, such as auditory, tactile or, most frequently, visual perception, for stimulation or feedback
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