Biomedical Engineering Reference
In-Depth Information
patients could use these technologies (Kübler and Birbaumer 2008). However, Birbaumer
and colleagues successfully tested a new procedure with CLIS successfully (personal
communication).
Although there is a well-established tradition in BCI research, there are only few studies
on the usability of BCIs (Pasqualotto et al. 2009, 2011b, 2011c) and a general lack of assessment
studies (Pasqualotto et al. 2011a). However, considering BCIs for communication as an
example, we can identify some limitations.
Only few studies have involved LIS patients in the long-term use of BCIs, and none of
them proved long-term efficacy. Although this technology is supposed to be usable for a
long time, studies with LIS patients generally only lasted a few hours. The effects of EEG
changes on long-term use of a BCI have not been assessed yet.
Another two problematic points that could affect the patients' evaluation of the
technology (and therefore affect the probability of abandonment) are the usability and
aesthetics of BCIs. At present, aesthetics could be seen as a secondary problem in the use
of this technology. However, it is important to note that traditional EEG is not appealing
to patients because of the electrodes and the cables; conductive paste that tends to dry
up in a few hours, thus needing replacement; and caps required for electrode placement.
The possible use of dry EEG electrodes and wireless technology (Popescu et al. 2007;
Gargiulo et al. 2010; Grozea et al. 2011) will probably improve the usability and therefore
the acceptance of BCIs.
Moreover, it is still necessary to improve the software to simplify operations. Although
several open-source platforms exist, handling communication still requires an external
operator. An alternative technical solution could be the hybrid BCI designed by Pfurtscheller
and colleagues (2010). A BCI usually relies on a single brain signal. A hybrid BCI could
consist instead of two or more different signals (such as EEG and GSR) and use one of them
as a “brain switch” or as a “selector” to detect a brain state that functions as a command.
To assess, it is necessary to identify the right tools for this process, and most of the
classical psychological questionnaires and physiological measures cannot be applied to
paralyzed persons (Birbaumer 2006). Parallel to the development of the BCI technology,
tools for evaluation should become available for those who will perform the assessment
process to match the technology with the users.
17.8 Conclusions
Beginning in the 1970s, the idea of communicating directly through brain activity shifted
from science fiction to actual applications. The increase of studies, funding, and papers
during the 1990s lead a large BCI community, documented in the First International
Meeting on Brain-Computer Interface Technology in 1999, to establish a shared definition:
A BCI is a psychophysiological system that does not depend on the brain's normal output
pathways of peripheral nerves and muscles.
Two different methods of electrophysiological recordings are normally used: invasive
and noninvasive. The invasive electrocorticography, which is characterized by intracranial
recordings of electrical activity with macroscopic electrodes or microelectrodes, records
directly from single neurons. The noninvasive method uses electroencephalography,
magnetoencephalography, functional magnetic resonance imaging, and near-infrared
spectroscopy to allow for control of a personal computer or a peripheral device. BCI
