This study investigates the relationship between the alpha rhythm (8-12 Hz) and brain activity using simultaneous EEG and fMRI. The researchers scanned 11 subjects at rest with their eyes closed to map regions where MRI signal changes reliably with posterior alpha activity. They found that increased alpha power was associated with decreased MRI signal in multiple regions of the occipital, superior temporal, inferior frontal, and cingulate cortices, and with increased signal in the thalamus and insula. These findings support the idea that the alpha rhythm is an index of cortical inactivity, possibly generated in part by the thalamus. The study also highlights the importance of simultaneous EEG and fMRI for understanding resting-state brain activity and the role of the thalamus in alpha rhythm generation. The method, termed simultaneous imaging for tomographic electrophysiology (SITE), combines the spatial localization power of fMRI with the electrophysiological information from EEG, offering a powerful tool for mapping EEG sources and studying other EEG spectral components.This study investigates the relationship between the alpha rhythm (8-12 Hz) and brain activity using simultaneous EEG and fMRI. The researchers scanned 11 subjects at rest with their eyes closed to map regions where MRI signal changes reliably with posterior alpha activity. They found that increased alpha power was associated with decreased MRI signal in multiple regions of the occipital, superior temporal, inferior frontal, and cingulate cortices, and with increased signal in the thalamus and insula. These findings support the idea that the alpha rhythm is an index of cortical inactivity, possibly generated in part by the thalamus. The study also highlights the importance of simultaneous EEG and fMRI for understanding resting-state brain activity and the role of the thalamus in alpha rhythm generation. The method, termed simultaneous imaging for tomographic electrophysiology (SITE), combines the spatial localization power of fMRI with the electrophysiological information from EEG, offering a powerful tool for mapping EEG sources and studying other EEG spectral components.