Experimental Protocol for On-Scalp MEG Detection of Gamma Band Neural Oscillations

Abstract

This thesis developed and validated an experimental visual stimulation protocol intended to induce gamma-band activity in the primary visual cortex. Gamma oscillations are associated with high level cognitive functions, such as sensory perception, problem solving and memory. They are therefore of interest when it comes to neuropsychiatric and neurological disorders, where disruptions in neural processing is often observed. In this context, visually induced gamma oscillations may serve as a useful biomarker to detect altered neural processing in the future. The aim of this thesis was to implement a visual stimulation paradigm capable of eliciting measurable gamma oscillations. It had to be compatible with the magnetoencephalography (MEG) environment. This included communication and synchronization with an existing acquisition software. In addition, the project involved establishing the visual presentation setup used to display the stimuli in the magnetically shielded room (MSR). The project encompassed literature studies, design of the stimulus, software development, conducting MEG-recordings and data analysis. Two types of stimulation protocols were implemented. One was based on paradigms identified in the literature, and one that explored a more novel approach to stimulus presentation. The results are promising in terms of integration and synchronization with the existing acquisition software. From the conducted MEG recordings, some indications of gamma activity were observed, although further testing and analysis are required to determine the reliability of these findings. In conclusion, the developed experimental protocol provides a functional basis for future studies investigating visually induced gamma activity.