How to study the brain by combining electrophysiology and fMRI
Electrophysiological and hemodynamic measures are the two most prominent tools to study brain function non-invasively in humans. The two methodological approaches are thought to provide largely complementary information on how the brain functions. EEG and MEG recordings provide a direct measure of neuronal responses with millisecond resolution, but have a relatively poor spatial resolution. FMRI on the other hand can inform us about where in the brain changes in neuronal activity occur with millimeter-level precision, while covering the entire brain or a large part of the brain. Hemodynamics-based techniques like fMRI however only provide an indirect measure of neuronal activity with a temporal resolution on the order of seconds. For these techniques to be truly complimentary it is important to understand how they relate to each other. In this presentation I will give an overview of empirical studies by myself and others in that have investigated this link by combining simultaneously recorded EEG and fMRI. I will discuss how oscillations can be related to different fMRI based brain regions and networks and how oscillations can have an effect on the routing of information through the brain. At the micro-scale I will illustrate how spectral changes across a wide spectrum relate to laminar specific BOLD-signal, and show preliminary results on how EEG power changes relate to changes in fMRI based laminar connectivity between brain regions.