Estimation of spatial distribution of the main rhythms of human brain activity using the method of functional tomography based on magnetic encephalography data

Three-dimensional structures of distribution of sources generating the main rhythms of electrical activity of the brain are found. The frequency bands of the following rhythms are considered: delta (1–4 Hz), theta (4–8 Hz), alpha (8–13 Hz), beta (13–35 Hz), and gamma (35–49 Hz). Experimental data obtained on 275-channel magnetic encephalographs at McGill University and the University of Montreal were considered. Magnetic encephalograms of spontaneous brain activity were recorded for 5 minutes in a magnetically insulated room. The spatial position of all elementary sources of brain activity was calculated by the method of functional tomography based on a detailed spectral analysis of multichannel magnetic encephalography data and on the solution of the inverse problem for localization of elementary oscillations at each frequency. Combining the data on the location and power of sources of all frequencies included in the considered rhythm generates a cloud of points, which is the source of this rhythm. For each rhythm, a cloud of points in the experimental space is shown, statistical characteristics of the distribution of sources are calculated. The proposed method can be used for a detailed quantitative study of brain activity.