D2.1 Requirements and Specification - CORBYS

D2.1 Requirements and Specification
Figure 42: Example EEG artefacts
15.4 The Role of EEG Artefacts in Non­Invasive BCIs
One of the most important aspects in biomedical signal processing is to acquire knowledge about noise and
artefacts in order to minimise them. Artefacts are undesirable signals that can occur in the signal acquisition
process and interfere with neurological phenomena. They may change the characteristics of EEG signal,
limiting the accurate evaluation of the running brain processes, and be even incorrectly used as the source
control in BCI systems (Fatourechi et al, 2007). This is the reason why it is of upmost importance to develop
automatic computer based methods that handle with artefacts, and this technology is a fundamental
requirement for a BCI system (Srnmo & Laguna, 2005). In EEG recordings (and as a consequence in EEG-
BCI systems) a wide range of artefacts can occur. While some of these artefacts can be easily identified, there
are others that may have similar characteristics to the neural activity and result extremely difficult to
recognise. One possible categorisation of artefacts is based on their origin: technical (originated from outside
the human body, such as the 50/60 Hz power-line noise, changes in electrode impedances, etc); and
physiological (arising from a variety of bodily activities, such as potentials introduced by eye or body
movements, muscular activity, cardiac activity, etc. Below (figure 4) some examples of artefacts are shown.
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