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1 Institute of Theoretical and Experimental Biophysics, Russian Academy of Sciences, Pushchino, Moscow District, Russia [email protected], [email protected] 2 Institute of Cell Biophysics, Russian Academy of Sciences, Puchshino, Moscow District, Russia [email protected] Pushchino State Institute of Life Sciences, Pushchino, Moscow District, Russia

Abstract. 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. Keywords: Waking guinea pigs
Cortical and subcortical structures
Oscillations
Cross-frequency analysis
Sensory stimulation
Cross-correlation

1 Introduction Brain processes depend on interactions between neuronal groups. Oscillations providing the synchronization and dynamic coordination of functionally linked neurons create favorable conditions for cognition [7, 27]. They are necessary for the execution of many cognitive functions, such as space orientation, selective attention, decision-making, and memory [2, 3, 13, 24–26]. Low-frequency (delta, theta, alpha) and high-frequency oscillations (gamma and ripples) have been intensively studied (reviewed in [1, 2]), and recently it has been specified that these different rhythmic activities participate in cognition [20, 25]. One of important oscillations in the brain is the theta rhythm: it correlates with learning and memory processes, especially in human [4, 9, 11, 14, 23]. The alpha rhythm (10–12 Hz) is associated with the ability to perceive external incentives and to react to them: dependence of reaction time and perception of signals on its phase was found in a number of works [6, 11, 15]. The gamma rhythm is often considered as a physiological © Springer International Publishing Switzerland 2016 L. Cheng et al. (Eds.): ISNN 2016, LNCS 9719, pp. 673–680, 2016. DOI: 10.1007/978-3-319-40663-3_77

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fingerprint of attention [8, 12]. There is also evidence that, whereas fast gamma oscillations are involved in the maintenance of relevant information, the slow alpha rhythm is implicated in suppressing irrelevant information in memory [10, 16, 19] and attention tasks [18, 22]. Despite increasing interest in rhythmic processes, the problems of how different types of oscillations can be synchronized during the processing of sensory signals and how changes in the expression of rhythmic activity affect the correlati