Self-paced operation of an SSVEP-Based orthosis with and without an imagery-based "brain switch:" a feasibility study towards a hybrid BCI.
This work introduces a hybrid brain-computer interface (BCI) composed of an imagery-based brain switch and a steady-state visual evoked potential (SSVEP)-based BCI. The brain switch (event related synchronization (ERS)-based BCI) was used to activate the four-step SSVEP-based orthosis (via gazing at a 8 Hz LED to open and gazing at a 13 Hz LED to close) only when needed for control, and to deactivate the LEDs during resting periods. Only two EEG channels were required, one over the motor cortex and one over the visual cortex. As a basis for comparison, the orthosis was also operated without using the brain switch. Six subjects participated in this study. This combination of two BCIs operated with different mental strategies is one example of a "hybrid" BCI and revealed a much lower rate of FPs per minute during resting periods or breaks compared to the SSVEP BCI alone ( FP=1.46+/-1.18 versus 5.40 +/- 0.90). Four out of the six subjects succeeded in operating the self-paced hybrid BCI with a good performance (positive prediction value PPVb > 0.70).
Institute for Knowledge Discovery, Graz University of Technology, 8010 Graz, Austria. pfurtscheller@tugraz.at
Gert
G
Pfurtscheller
Teodoro
T
Solis-Escalante
Rupert
R
Ortner
Patricia
P
Linortner
Gernot R
GR
Müller-Putz
D000328:Adult; D000465:Algorithms; D001186:Artificial Limbs; D001921:Brain / Q000502:physiology*; D003463:Cues; D003627:Data Interpretation, Statistical; D004569:Electroencephalography; D004867:Equipment Design; D019054:Evoked Potentials, Motor / Q000502:physiology*; D005074:Evoked Potentials, Visual / Q000502:physiology*; D005240:Feasibility Studies; D005260:Female; D006225:Hand / Q000502:physiology; D006801:Humans; D007092:Imagination / Q000502:physiology*; D008297:Male; D009044:Motor Cortex / Q000502:physiology; D009989:Orthotic Devices; D011597:Psychomotor Performance / Q000502:physiology; D014584:User-Computer Interface; D014793:Visual Cortex / Q000502:physiology; D055815:Young Adult