Rhythmic alpha-activity generators in the human EEG.

This study was designed to locate the neuronal mechanisms of rhythmic activity in the human brain in the alpha-rhythm range using an equivalent dipole model. The experiments approach used here is based on using the "imposed rhythm" phenomenon, whereby a light stimulus flashing with a frequency close to the frequency of the individual alpha rhythm increases its power in the EEG spectrum. The results obtained showed that the activity of the structures generating the alpha rhythm could be differentiated by using a specific photostimulation frequency and were located by constructing a dipole model. Two sources of alpha-rhythm generation were found, located in the thalamic structures of the brain and operating over a narrow-band frequency range with maximum response resonance frequencies of 10.1 and 10.5 Hz.