title: An SSVEP BCI to control a hand orthosis for persons with tetraplegia.
abstract: Brain-computer interface (BCI) systems allow people to send messages or commands without moving, and hence can provide an alternative communication and control channel for people with limited motor function. In this study, we demonstrate a BCI system for orthosis control. Our BCI was asynchronous, meaning that subjects could move the orthosis whenever they wanted, instead of pacing themselves to external cues. Seven subjects each performed two tasks with a BCI that relied on steady state visual evoked potentials (SSVEPs). Although none of the subjects had any training, six subjects showed good control with a positive predictive value (PPV) higher than 60%. The overall PPV for all subjects reached 78% ±10%. However, the false positive rate was high, and some subjects dislike the flickering lights required in SSVEP BCIs. In follow-up work, we hope to reduce both the false positive rate and the annoyance produced by flickering lights by hybridizing this BCI with a "brain switch," which could allow people to turn the SSVEP system on or off using a second type of brain activity when they do not wish to control the orthosis. We also hope to validate this approach with people with tetraplegia.
authors.affiliation: Guger Technologies OG, 4521 Schiedlberg, Austria. ortner@gtec.at
authors.forename: Rupert
authors.initials: R
authors.lastname: Ortner
authors.forename: Brendan Z
authors.initials: BZ
authors.lastname: Allison
authors.forename: Gerd
authors.initials: G
authors.lastname: Korisek
authors.forename: Herbert
authors.initials: H
authors.lastname: Gaggl
authors.forename: Gert
authors.initials: G
authors.lastname: Pfurtscheller
mesh_terms: D001676:Biofeedback, Psychology / Q000379:methods; D004569:Electroencephalography / Q000379:methods*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D006225:Hand / Q000503:physiopathology*; D006801:Humans; D009989:Orthotic Devices; D011782:Quadriplegia / Q000503:physiopathology* / Q000534:rehabilitation*; D012371:Robotics / Q000379:methods; D014584:User-Computer Interface; D014793:Visual Cortex / Q000502:physiology