Thesis defense Saskia Haegens (Donders Series 77)

30 March 2012

Promotor: Prof.dr. D.G. Norris, copromotor: Dr. O. Jensen

On the functional role of oscillatory neuronal activity in the somatosensory system

This thesis examines the functional role of oscillatory brain activity within the context of somatosensory discrimination performance. Using both working memory and attention paradigms, it examines how oscillations serve to shape the functional architecture of the brain. Taking a network perspective, including task-relevant and task-irrelevant regions, is important to address this question. Oscillatory activity as measured with MEG and LFP recordings was studied in relation to both neuronal processing (in terms of single neuron spikes) and the subsequent behavioral performance of the subject, thereby covering the full range from single cells to the systems level.

As a general rule, beta and gamma band activity were found to be reflective of engaged regions, whereas alpha activity was reflective of functionally disengaged regions. In addition, the studies in this thesis show that oscillations do not just correlate with function, but have a profound influence on actual neuronal processing and subsequent behavior. Importantly, this thesis demonstrates that alpha activity reflects a general mechanism for functional inhibition, modulating spike firing in a phasic manner, and subsequently influencing behavioral performance.