Information Technology Reference
In-Depth Information
3.1
Music BCIs: The Challenges
EEG approaches have been applied in the domain of music for decades due to
EEG
s temporal resolution when compared to other brain information retrieval
techniques, and also because it is considerably more cost effective and portable than
the alternatives (e.g. fMRI
1
, fNIRS
2
).
One would assume contemporary EEG-based BCMIs would draw from the state
of the art in generalisable EEG. However, neurofeedback techniques that use
spontaneous potentials (i.e. oscillations in raw EEG signals), or what are commonly
called
'
to understand and decode information from the
brain are a popular method for consumer and research level BCMIs, largely because
this approach is
“
Brainwave Frequencies
”
'
baked in
'
to various BCI devices that are commonly sold in the
marketplace.
These approaches can be unreliable and challenging for users to control, and are
therefore not as prevalent in other forms of EEG research as some other, more
accurate methods. One such method is the ERP, or Event Related Potential tech-
nique, which is widely used in BCIs and psychology research (Grierson et al.
2011
;
Miranda et al.
2004
; Chew and Caspary
2011
; Nunez
2006
).
3.2
P300 ERP Based Music BCIs
3.2.1 What Are ERPs?
ERPs are speci
c brain signals that can be detected in raw EEG data following the
onset of a stimulus
for example, the beginning of a sound, or a change in the
motion or visual appearance of an image or other sensory experience. There are
many types of ERPs, each one thought to represent a different stage and/or process
in the unconscious and conscious encoding of events by the brain. They can also be
an indication of the way in which you are experiencing a particular stimulus
—
—
for
example, such as whether you consciously noticed a particular event or not.
3.2.2 What Is the P300?
Under certain conditions, ERP components can be seen as amplitude curves and
peaks derived from the raw EEG time series. They can be either positive or negative
with respect to the baseline brain signal, and happen on or around particular points
in time following a sensory input event. These two factors
—
their polarity and
timing
provide the method by which they are labelled. For example, the N100 (or
N1) is a negative peak approximately 100 ms after the onset of a sensory event that
—
1
functional Magnetic Resonance Imaging.
2
functional Near-Infrared Spectroscopy.
