Alpha rhythm operational architectonics in the continuum of normal and pathological brain states: current state of research.

In the present study, we explore the operational architectonics of alpha activity in different normal and pathological brain states. Aggregated analysis of a set of diverse previously conducted EEG/MEG experimental studies was performed within the same methodological and conceptual framework. It was shown that the characteristics of short alpha activity periods (segments), as well as the spatial structural synchrony of alpha activity, changed considerably in accordance with the type of brain functional state, stimulation, cognitive task, pharmacological influence, and the type of pathology. The results of this study suggest that particular neurophysiological pattern(s) of cortex alpha activity indicates a resting state network, which is characterized by well-defined structure in both the temporal as well as the spatial domain. The optimal functional state of the brain depends upon a delicate metastable balance between local specialized processes and their global integration. Excess or lack of either component would be a deviation from the optimal condition and can lead to pathology. The fact that all observed results were significantly different from surrogate EEG data reflects a non-occasional nature of spatio-temporal dynamics in the operational architectonics of alpha activity. Better understanding of the specific ways in which disrupted dynamics of different characteristics of alpha-generating neuronal assemblies (and their functional connectivity) may underlie neuro/psychopathology might suggest new targets for therapeutic agents.