Analysis of oscillations in the brain during sensory stimulation: Cross-frequency relations

Oscillations are necessary for the execution of many cognitive functions. Little attention has been given to the problem of how various types of oscillations are synchronized during information processing. We analyzed the power and correlation characteristics of rhythmic activities in theta, alpha, and gamma ranges when animals were in two behavioral states: quiet wakefulness and the processing of sensory signals. Eight brain areas (cortical and subcortical) were examined. During sensory stimulation, a strengthening of oscillations of all ranges was revealed in many structures. The main result of this study is that cross-frequency relations in all oscillatory bands in cortical and subcortical structures sharply increased during the processing of sensory information.