Traditional Buddhist meditations reduce mismatch negativity in experienced monk- practitioners.

Thousand-year-old Buddhist traditions have developed a wide range of methods for the subjective exploration of consciousness through meditation. Combining their subjective research with the possibilities of modern neuroscience can help us better understand the physiological mechanisms of consciousness. Therefore, we have been guided by specifically Buddhist explanations when studying the physiological mechanisms of altered states of consciousness during Buddhist meditations. In Buddhism, meditations are generally divided into two large categories: (1) one-pointed concentration and (2) analytical meditation. Maintaining both one-pointed concentration and analytical meditation on 'bodhicitta' ("the thought of awakening") and 'emptiness' is a necessary condition for transitioning into tantric practices. Tantric practices involve sophisticated visualizations of Buddhist deities, the 'energy structure' of the human body, and the visualization of the stage-by-stage process of dying accompanied with the dissolution of body elements. According to Buddhism, these meditations are characterized by the gradual withdrawal from "gross levels" of consciousness associated with the five senses. From a psychophysiological perspective, this withdrawal of sensory consciousness can be considered as the decrease of sensory stimuli recognition and attentional disengagement from the external world. We concentrated on how considered meditations affect sensory and cognitive processing of external stimuli. Auditory event-related potentials (ERPs) in the passive oddball paradigm were studied both during meditations and in a controlled state of relaxed wakefulness. It was shown with a group of 115 Buddhist monks that during meditation, mismatch negativity amplitudes, amplitudes of N1 and P2 components of ERPs to deviant stimuli, and the amplitudes of the P3a component to novel stimuli all decrease. These outcomes suggest that the considered Buddhist meditations, compared to the control state of relaxed wakefulness, are accompanied by a decrease in physiological processes responsible for maintaining attention on the outside world and recognizing changes in the stream of sensory stimuli.

[EEG Beta and Gamma Powers When Comparing Certain Psychophysiological States with Normal and Weakened Electromyogram of Facial Muscles.]

The aim of the present study was to investigate EMG contamination on high-frequency scalp electroencephalogram (EEG) during comparisons of certain cognitive tasks performance. 19 healthy women who performed similar test tasks before and after cosmetic injections of Dysport in various face regions for reduction of facial muscles activity took part in the study. The test tasks were focused on induction of emotional states with different valences, on memory storing and extraction of verbal information. Default state of rest was uncluded too. During performance of the tasks, parallel registrations of EEG from a scalp surface(19 channels) and EMG from several facial muscles (6 channels) were carried out. Changes of spectral power in ß2 and low γ frequency ranges (18-40 Hz) in EEG- and EMG-derivations after Dysport injections were analyzed. Changes of spectral power in the same derivations during comparisons of the different test tasks were analyzed before and after Dysport injections separately. It was demonstrated that Dysport injections lead to reduction of EMG power in regions of injections and to reduction of EEG power in frontal and temporal derivations. However, the EEG-correlates revealed when comparing different test tasks remain qualitatively invariable both after, and before Disports injections. These facts confirmed that EMG makes a noticeable contribution to the electric activity registered from a scalp in the frequency ranges more than 18-Hz. At the same time, it was shown that in certain experimental situations influence of EMG not necessarily interferes with identification of EEG-correlates of mental activity during EEG registration from a head surface in ß2 and low γ frequency ranges.