Predictive BCI Speller based on Motor Imagery

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Part 1: Project profile

Project name

BCI based on Motor Imagery

Project short description

This project is aimed is to control an external device through the analysis of brain waves measured on the human scalp.


Start date: 01/05/2008

End date:


People involved

Project head(s)
Other Politecnico di Milano people
Students currently working on the project

Laboratory work and risk analysis

Laboratory work for this project will be mainly performed at AIRLab-IIT/Lambrate. The main activity consists in the acquisition of brain signals through an EEG amplifier for on-line or off-line processing. This is a potentially risky activity since there is an electrical instrumentation that is in direct contact with the human body. It is thus important to keep the system isolated from the power line. The EEG amplifier (as all biomedical instrumentations) is certified by the vendor to be isolated and the acquired data are transferred to the PC using an optic fiber connection . Anyhow for increased safety the PC and any other electronic device connected to the system must be disconnected from the power line. Standard safety measures described in Safety norms will be followed.

Part 2: Project description

The goal of this project is to implement a BCI system supporting people with motor disabilities to communicate effectively. The main idea is to adopt the "virtual keyboard" paradigm in which a series of symbols are selected by means of a BCI interface.

This kind of communication can be included in the class of Alternative and Augmentative Communication (AAC) and the main issue with it is in the need of minimizing the number of selections required by the user while running the application. Indeed the selection process could be costly (both in terms of time and effort) for the target users of these kinds of systems.

The adoption of a BCI interface, moreover, sets also a limit to the number of alternative choices available for each selection. This limit depends on the specific BCI paradigm used and on the way the selection process is carried out. Using a scanning approach, for example, it is possible to overcome this kind of limit, but introducing the drawback of much longer selection delays.

With a direct selection, instead, it is possible to classify effectively a very limited number of states, usually 2,3 or 4 depending on the BCI paradigm adopted. The Motor Imagery paradigm is somehow different because it could be used to translate sensymotor rhythms in the continuous movement of a cursor in 2 dimensions. In this case it is possible to associate a choice with a target on the screen and perform a selection just hitting with the cursor the corresponding target. In this case the number of different choices is limited only by the precision of the cursor movement that can be achieved.

Part 3: References

  • Control of two-dimensional movement signals by a noninvasive brain-computer interface in humans, Wolpaw J.R., McFarland J., PNAS, vol. 101, no. 51, december 2004, pages 17849-17854.
  • Brain Computer interfaces for communication and control, Wolpaw J.R., Birbaumer N., McFarland D., Pfurtsheller G., Vaughan T., Clinical Neurophysiology 113, 2002, 767-791
  • EEG based communication: prospects and problems, Vaughan T., Wolpaw J.R., Donchin E., IEEE transactions on rehabilitation engineering, vol. 4, no. 4, december 1996, pages 425-430.