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PubMedDate not supplied

[The dynamics of the dominant alpha-rhythm frequency in the perception and reproduction of time intervals].

Dependence of the dominant alpha frequency on the processes of perception and subsequent reproduction of time intervals by rhythmic hand pressing was analysed. Two groups of subjects were separated, which demonstrated either an increase (I) or a decrease (II) in the dominant alpha frequency after the transition from perception to reproduction. In the I group 83% of the subjects reproduced time intervals with a delay. In the II group reproduction in advance was observed in 75% of the subjects. The dynamics of the dominant alpha frequency probably reflects formation of the optimal functional state underlying the individual level of activation and properties of the higher nervous activity in the subjects from both groups.

Acoustic Stimulation↗
PubMedDate not supplied

[Alpha-rhythm of the EEG in directed attention].

Degree of manifestation and synchronization of rhythmic alpha-range components in various cortical areas was studied in healthy adult subjects in conditions of controlled computer experiment by spectral-correlation method of EEG analysis during directed attention previous to discrimination of tactile, auditory and visual stimuli. The obtained results show that in preparation for discrimination of heteromodal stimuli, specific reconstructions take place of alpha-range electrical activity determined by signal modality. These changes are expressed in a local increase of the degree of synchronization of alpha oscillations in those projection and associative brain areas which are connected with the analysis of the given stimuli. Functional significance of these reconstructions is seen in the fact that they are significantly more expressed at correct recognition. A hypothesis is suggested about participation of the alpha-range in neurophysiological mechanisms of directed attention.

Adult↗
PubMed1981

[Characterization of genetic EEG-variations with the amplitude-interval-analysis. I. Variations of alpha-activity; flat-EEG; borderline flat EEG, occipital slow beta-waves; monotonous alpha-rhythm (author's transl)].

In 121 healthy adult male probands with different variants of alpha-activity (monotonous alpha-waves; low voltage EEG, borderline low voltage EEG; occipital slow beta-waves) a quantitative description of unipolar leads was carried out using a program for amplitude-interval (time-domain) analysis. Statistically significant differences between means of the examined parameters were discovered between the various EEG variants. No single parameter, however, separates these variants reliably. For such a separation, methods of multivariate statistics will have to be used. Significant differences between right and left hemispheres (primarily lower alpha-activity together with higher beta-activity on the left hemisphere) were found in all EEG types examined except the variant with monotonous alpha-waves.

Alpha Rhythm↗
PubMed2004

Visually evoked phase synchronisation changes of alpha rhythm in migraine. Correlations with clinical features.

We investigate phase synchronisation in EEG recordings from migraine patients. We use the analytic signal technique, based on the Hilbert transform, and find that migraine brains are characterised by enhanced alpha band phase synchronisation in the presence of visual stimuli. In migraine, the brain synchronises to the idling rhythm of the visual areas under certain photic stimulations; hypersynchronisation of the alpha rhythm may suggest a state of cortical hypoexcitability during the interictal phase of migraine.

Adult↗
PubMed1985

Mu and alpha rhythm in comatose children.

Three anoxic comatose children had EEG alpha-like activity and in two of them mu rhythm was recorded. The paradoxical appearance of these electrical activities in comatose children seems to indicate a grave prognosis. A possible role for barbiturate treatment in this phenomenon is not excluded.

Alpha Rhythm↗