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At least 19 recordsLinked to original sources
PubMed1975

Ongoing occipital rhythms and the VER. I. Stimulation at peaks of the alpha-rhythm.

As a first step toward determining the source of variability in the visually evoked response (VER) between subjects, we have examined the relationships between the VER and the alpha-rhythm. This was done by comparing the VER's to photic stimuli delivered at positive and negative peaks of the alpha-rhythm (alpha-synchronized stimuli) with VER's to flashes delivered at a fixed interval, unsynchronized with the alpha-rhythm. Average VER's for the three classes of stimuli were calcuated for each of ten subjects. In addition, a grand average VER (GVVER) WAS CALCULATED FOR EACH STIMULUS CLASS BY AVERAGING THE INDIVIDUAL AVERAGE VER's. Quantitative comparisons between GVER's were made using cross- correlograms. Cross-correlograms were calculated between each of the GVER's, and between the GVER's to alpha-synchronized stimulation and their controls. These data show that the first 120 msec. poststimulus interval of the Gver's to alpha-synchronized stimulation are highly correlated with the prestimulus alpha- rhythm. The data also show a component occurring in al GVER's which is independent of the alpha-rhythm. This component begins 120 msec. After stimulation, reaches peak amplitude at 200 msec, and decays to baseline at 240 msec. Thses findings suggest that much of the variability in VER recordings may be due to alpha-activity which has been insufficiently attenuated by averaging.

Adult↗
PubMed1979

Personality and male-female influences on the EEG alpha rhythm.

The amplitude and frequency of the alpha rhythm was measured in electroencephalic recordings from 45 male and 46 female university students. The mean alpha frequency of the female group was significantly greater than the male group. There was no significant difference in alpha frequency between females in the first half of the menstrual cycle and those in the second half. The relationship between questionnaire measures of psychoticism, extraversion and neuroticism, and the alpha rhythm was investigated using analysis of variance, correlation analysis and factor analysis. Alpha amplitude was significantly greater in extraverted subjects, alpha amplitude and extraversion scores were significantly correlated and both had high loadings on a single factor. No relationship between psychoticism or neuroticism and alpha frequency or amplitude was observed.

Adult↗
PubMed1979

[Adaptive regulation of cerebral biopotentials (alpha-rhythm) in neurotic patients].

With the aid of a feedback towards an increase in the EEG intensity, adaptive regulation of brain biopotentials (alpha-rhythm) was conducted in 22 patients with different forms of neurosis. It was established that in patients with an initial low level of alpha-rhythm its regulation was more significant, while in patients with an initially middle level of alpha-rhythms in the EEG, its regulation was less expressed. The clinical effect of regulation in all cases was positive. The study also demonstrated a crosscorrelation of connections in the process of regulation between such functions as alpha-rhythm-EMG, alpha-rhythm-SGR, etc. It is suggested that, regulation of alpha-rhythms can be accepted as a therapeutic approach in the treatment of patients with neuroses.

Adult↗
PubMed1978

Thalamic control of spontaneous alpha-rhythm and evoked responses.

EEG, depth recordings from the thalamus, visual-evoked potentials, and readiness motor potentials were analyzed with a computer in 40 patients with involuntary movements and intractable pain who underwent stereotactic thalamotomy. It was demonstrated that there were significant correlations in alpha-rhythms between the ventrolateral (VL) nucleus and the frontocentral cortex, and also between the centromedian nucleus and the centroparietal cortex, with the phase difference of the cortex lagging behind the thalamus. Relationships between the thalamic VL nucleus and the frontocentral cortex were significant not only in alpha-rhythms, but also in evoked responses following photic stimulations, voluntary movements, and electrical thalamic stimulation. Thalamotomy produced a bilaterally decreased synchronization of the cortical alpha-rhythms, which recovered within 6 months.

Alpha Rhythm↗
PubMedDate not supplied

[Directed regulation of human alpha-rhythm using feedback].

Directed control of intensity of the alpha-rhythm in the somatosensory cortical regions was examined in 20 healthy subjects in conditions of combined (visual and auditory) feedback connection. An attempt has been made to single out by means of control experiments, the factors influencing in such conditions of external stimulation the brain bioelectrical activity. A study was made of the changes in effectiveness of biocontrol in multiple (five) sessions of training. Data are given on the dynamics of some vegetative functions in controlling brain biopotentials.

Adolescent↗
PubMed1979

Feedback control of human alpha rhythm from the central area.

Twenty subjects, aged 17 to 25, were given from 5 to 10 sessions of training in controlling alpha. They were divided into three groups, respectively reinforced for increasing alpha from the central area, reinforced for decreasing alpha from the central area, and given noncontingent reinforcement. Compared with the initial baseline, the alpha of the noncontingent subjects did not change, while those reinforced for increases were reliably higher and those reinforced for decreases reliably lower than the noncontingent group. A slight trend toward improvement during successive sessions was not reliable. Since the experiment was conducted in the Soviet Union, the subjects had no expectations of an "alpha experience." Although tests showed a slight elevation in mood at the end of the sessions, there were no differences among the groups. There was an increase in reports of fatigue after the training sessions. There were no reports of using visual or somatomotor maneuvers as a means of controlling alpha. Furthermore, alpha rhythm control was not found to be consistently correlated with changes in heart rate, respiration, or mood, as determined by cross-correlation analysis.

Adolescent↗
PubMed1978

[Statistical spectral study of alpha rhythms: modifications due to the tardive action of a hypnotic (author's transl)].

In a simple blind study to evaluate electroencephalographic criteria objectively, and to continue characterization of psychotropic compounds, 5 mg of nitrazepam, a hypnotic derivative, was given to seven subjects the night before the recording. We noted that in most subjects there was a reduction in the spectral intensity of the alpha rhythm, associated with a greater frequency instability, several hours after the absorption of nitrazepam. This corresponds to the tardive hypnotic action of the psychotrope, the importance of which is wellknown at the present time. In the same way as the increase in rapid rhythms, the slipping of 0.5 c/s of the dominant alpha frequency to the top could be characteristic of the action of nitrazepam.

Adult↗
PubMed1978

The alpha rhythm.

Explore the source record for details and available documents.

Alpha Rhythm↗
PubMedDate not supplied

[Voluntary synchronization and desynchronization of alpha rhythm by retroaction of EEG rhythms. Preliminary study (author's transl)].

Research was carried out on twenty subjects on the volontary control of alpha rythm by retroaction. Retroaction was provided in real time as a sound indicating the presence of alpha bursts or the intervals between bursts when reaching a pre-selected amplitude threshold, in such a way as to ensure that the alpha Index of the control situation (LB) reached about 50% of its total length. There are five situations per session: the initial state or base line (LB), relaxation with eyes closed (DF) and eyes open (DO), concentration with eyes closed (CF)and eyes open (CO), each situation being subdivided into 4 one-minute sequences. Subjects are informed about the alpha Index achieved at the end of each sequence, thus creating a periodic reinforcement. From the outset, three subjects showed an evident ability to increase or decrease at will the alpha occurrence rate, which gradually improved as the sequences progressed. Three other subjects showed that the same ability but to a lesser extent. Subjects confirmed that the feedback signal helped them to determine the most effective strategy for voluntary control, thus indicating that training is possible and that it is greatly facilitated by feedback, at least in the early stages. A detailed analysis of the recordings has made it possible for us to formulate hypotheses about the most important aspects of this control.

Alpha Rhythm↗
PubMed1978

Spectral analysis of alpha rhythm during Schultz's autogenic training. A tentative approach to rapid visualization.

The records from experimental sessions including autogenic standard exercises and other conscious states, in two long-term trainees, were treated by using a frequency analysis programme. Starting from a synoptic reduced representation of the data and selecting sequences for the building of histograms of averaged energy levels in limited frequency bands, the authors describe the progressive spread of a dominant alpha band all over the scalp during autogenic training.

Adult↗