Authors:
Samuel W. Hincks
1
;
Maya DeBellis
1
;
Eun Youb Lee
1
;
Ronna ten Brink
1
;
Birger Moëll
2
and
Robert Jacob
1
Affiliations:
1
Tufts University, United States
;
2
Stockholm University, Sweden
Keyword(s):
BCI, Implicit Brain-computer Interface, fNIRS, Near-infrared Spectroscopy, tDCS, Transcranial Direct Current Stimulation, Cognitive Workload, Bidirectional Brain-computer Interface, Entropic Brain-computer Interface, N-back, ADHD, Attention.
Abstract:
We envision a future user interface that measures its user’s mental state and responds not only through a
display but also by sending output directly to the brain, leading to a primitive bidirectional brain-computer
interface. Previous interactive systems have measured brain state with functional near-infrared spectroscopy
(fNIRS) for communication from user to computer; we now explore transcranial direct-current stimulation
(tDCS) as a channel in the opposite direction. Our goal is to integrate this with brain measurements from
fNIRS, so that the stimulation parameters governing tDCS may be set dynamically to enhance user cognition
based on current mental state and task demands. To do this, the first step is to determine how long it takes for
tDCS to register cognitive effects and how long these effects last. We present an experiment that investigates
the temporal dimension of tDCS for this purpose. The findings suggest a long lag-time between the onset
of stimulation and a
ny measurable cognitive effect, which may prohibit the effectiveness of tDCS in a brainadaptive
application.
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