Thesis defense Koen Koenraadt (Donders Series 153)

27 March 2014

Promotors: Prof.dr. J. Duysens, Prof.dr. P.W.M. Desain

Copromotor: dr. N.L. Keijsers

Shedding light on cortical control of movement

A brain-computer interface (BCI) allows the use of own brain activity to control external devices. In the current thesis the potentials are explored of functional near-infrared spectroscopy (fNIRS), a relatively new neuroimaging technique. This technique uses optodes consisting of glass fibers, which are positioned on the scalp. fNIRS measures changes in oxygenated (HbO) and deoxygenated blood (HbR) in the superficial layers of the brain.

The first part of the thesis focuses on the methodology of fNIRS by aiming to improve the optode positioning procedure and the signal strength. An attempt to locate the optimal position with transcranial magneto-stimulation revealed no improvements compared to the conventional positioning procedure. A center-of-gravity based on the HbR signals of multiple channels showed the possibility to distinguish between hand and foot movements. In the second part of the thesis the feasibility of fNIRS in motor control studies was explored. fNIRS demonstrated to be useful in fundamental motor control studies and even showed the possibility to be used during complex walking on a treadmill. In the last part of the thesis, the use of fNIRS in a BCI setting was investigated. First, we introduced attempted foot movements by spinal cord injury patients as a potential paradigm for future BCI. Finally, SCI patients successfully used this paradigm to control an avatar on the computer screen. This paves the way for using fNIRS in future BCI studies and applications.