My area of interest is the detection of the epileptogenic zone with the help of MEG in patients with pharmacoresistant epilepsy who are candidates for surgical treatment. I am inspired by the unique possibility of this method to differentiate the neuronal activity of the epileptogenic zone (i.e., the critical zone of initiation of the seizure) from the zones of secondary distribution of epileptic activity. MEG is especially informative immediately before the seizure onset, when the epileptogenic zone most clearly manifests itself. High sensitivity of MEG to local activity of the cerebral cortex allows us to detect high frequency activity - the most common pattern of the seizure onset according to invasive electrocorticography. Thus, the possibilities of MEG bring us closer to a diagnostic accuracy of invasive studies. Analysis of the preictal and ictal MEG is especially important for patients with multiple epileptic foci, such as in tuberous sclerosis. Detection of the leading source and its subsequent surgical removal is an effective method of epilepsy treatment in patients with this diagnosis. In the majority of cases MEG allows detection of the leading epileptic focus much more accurately than EEG, selecting it from a variety of active zones. This method can give clinicians unique information necessary for a favorable outcome of surgical treatment.