Introduction: Simultaneous EEG-fMRI registration is rapidly evolving and has received substantial attention. This technique provides precise information in both spatial and temporal domain. The biological basis of the EEG and fMRI signal is different which, on the one hand makes results interpretation more difficult but, on the other hand, gives more convincing arguments on the neural correlates of sensory and cognitive processes. In this paper we present an example of implementation of simultaneous EEG-fMRI registration for alpha rhythm source mapping.
Material and methods: 60 young males took part in this study. For the group analysis we selected 33 individuals to obtain homogenous group. Siemens Magnetom Trio 3T and 64-electrode SynAmp2 Neuroscan EEG system was applied. Participants took part in fMRI imaging which adapted arrest reaction study.
Results: Averaged spectra amplitude distribution of alpha rhythm (8-13Hz) showed high activation in the occipito-parietal region and smaller but noticeable activity in the frontal area. FMRI results revealed activity in bilateral occipital lobe. Additional regions included the posterior cingulate gyrus, middle and superior frontal gyrus. Statistically significant areas with BOLD signal decrease were located in the temporal lobe and anterior cingulate gyrus.
Conclusion: The obtained results indicate overlapping regions of the presented EEG outcomes and fMRI maps for alpha rhythm study. Simultaneous EEG-fMRI technique allows for registration of spontaneous EEG activity with both high temporal and spatial resolution. The alpha rhythm might reflect the extensive brain process involving the thalamo-occipito-frontal connections.