10th AEARU Workshop on Computer Science and Web Technology
February 25-27, 2015, University of Tsukuba, Japan
PosterSpatial Tactile Brain-Computer Interface by Applying Vibration to User’sShoulders and Waist
Takumi Kodama1*, Shoji Makino1 and Tomasz M. Rutkowski1,21Life Science Center of TARA, University of Tsukuba, Tsukuba, Japan
2RIKEN Brain Science Institute, Wako-shi, Japane-mail: {takumi, tomek}@bci-lab.info
Abstract We aim at an augmentation ofcommunication abilities of locked-in syndrome(LIS) users by creating a brain-computer interface(BCI), which can control a computer or otherdevice by using only brainwaves. As a method, we
use a stimulus-driven BCI based on vibration
stimuli delivered via a gaming pad to the user’sshoulders and waist. We identify P300 responses
from brainwave data in response to the vibration
stimuli. The user’s intentions are classified
according to the P300 responses recorded in theEEG. From the results of the experiments, we areable to classify successfully the brainwave P300 or
the so-called “aha-”responses.
Keywords Brain-computer interface; locked-insyndrome (LIS); stimulus-driven BCI; P300; EEG.
I. INTRODUCTION
Recently in neurotechnology applications, thevibrotactile-based somatosensory modality BCIs havegained in popularity [1, 2]. In this abstract we report a
successfully implemented alternative tactile BCI thatuses brainwave P300 responses (a so-called “aha”) to asomatosensory stimulation delivered to the user’s
shoulders and waist, defined as a back-tactile BCI(btBCI).
We report on experiments conducted by applying
vibration stimuli to the user’s shoulders and waist,
which allows us to stimulate places at larger distanceson the body in order to verify our hypothesis of the fullbody-based tactile BCI paradigm validity.
In the experiments reported in this abstract, theusers lay down on the vibrotactile-stimulating pad andinteracted with stimulus patterns delivered in an
oddball-style paradigm to their shoulders and waist, asillustrated in Figure 1.

II. METHODSIn the research project reported in this abstract theonline EEG experiments were carried out with sevenhealthy BCI-naive users (three males and fourfemales) with a mean age of 25 years (standarddeviation of 7.8 years). All the experiments wereperformed at the Life Science Center of TARA,
University of Tsukuba, Japan (experimentalpermission no. 2013R7). In the btBCI online
experiments, the EEG signals were captured with abio-signal amplifier system g.USBamp by g.tec
Medical Instruments, Austria. Active EEG electrodes
were attached to the sixteen head locations. The EEG
signals were captured and classified by in-housemodified BCI2000 software. The EEG recording
sampling rate was set at 512 Hz, and the high and low
pass filters were set at 0.1 Hz and 60 Hz, respectively.
The notch filter was set for a rejection band of48 ~ 52 Hz. The vibrotactile spatial pattern stimuli(stimulated body locations used as cues) in the two

Figure 1. A btBCI user lying on the vibrotactile pad as in
the experiments reported in this abstract. The g.USBamp byg.tec with g.LADYbird EEG electrodes is also depicted. The
photograph is included with the depicted user permission.

Figure 2. Grand mean averaged ERP for attended (purple lines) and ignored (blue lines) stimuli. The very clear “aha-”
responses are easy to notice for each EEG electrode in the latencies of 200 ∼ 800 ms.

experimental settings were generated using the sameMAX 6 visual programing application.
III. RESULTS

The EEG experiment results are summarized inFigure 2 in the form of grand mean averaged
brainwave event related potentials (ERPs). The results
elucidated very clear “aha-”responses in latency rangesof 200 ~ 800 ms. Mean information-transfer-rates(ITRs) ranged from 0.6 bit/min to 3.3 bit/min, for 10trials averaging based step-wise linear discriminant
analysis (SWLDA) classification, to 0.5 bit/min to10.9 bit/min for single trial offline analysis cases.
IV. CONCLUSIONSThis abstract reports results obtained with a novel
six-command-based btBCI prototype developed andevaluated in experiments with seven healthy BCInaive users. The experiment results obtained in thisstudy confirm the validity of the btBCI for six
command-based applications and the possibility tofurther improve the results. The EEG experiment withthe prototype confirms that tactile stimuli applied tolarge areas of the back can be used to interact with sixcommands-based applications.

The results presented offer a step forward in thedevelopment
ofsomatosensory
modality
neurotechnology applications. Due to the still not
perfect interfacing rate achieved in the case of theonline btBCI, the current prototype obviously requires
improvements and modifications. These requirements
will determine the major lines of study for future
research. However, even in its current form, theproposed btBCI can be regarded as a possible
alternative solution for locked-in syndrome patients,
who cannot use vision or auditory based interfaces due
to sensory or other disabilities.
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