Study of the Role of Resonance Phenomena in Brain Responses to Rhythmic Photostimulation with Linearly Increasing Frequency

The issue of the mechanisms underlying brain responses to rhythmic photostimulation generates contradictory opinions. To identify the mechanisms of rhythmic photostimulation, it is necessary to analyze individual spectra using the most detailed set of stimulation frequencies. In this paper, in order to assess the role of resonance phenomena in the effects of rhythmic photostimulation, an analysis of the fine structure of individual EEG spectra was performed during rhythmic photostimulation, the frequency of which smoothly increases linearly from 1 to 20 Hz. It was found that within each of the main EEG frequency ranges (delta, theta, alpha, and beta), discrete sections of the individual EEG spectrum are detected that are resonantly activated in the subject when the stimulation frequency or its harmonics coincide with their natural frequency. The basic role of resonance mechanisms is demonstrated when considering the advantages of resonance scanning, a promising version of rhythmic photostimulation, in which the stimulation parameters are set programmatically with a step-by-step increase in frequency.