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At least 19 recordsLinked to original sources
PubMed1978

The relationship of head size to alpha frequency with implications to a brain wave model.

Analogies between brain waves and waves in physical systems suggest that EEG frequency may be partly determined by cortical surface area. Since a number of other physiological and anatomical parameters probably influence EEG frequency, only a weak correlation is to be expected. A study was made of 159 subjects, some of whom had either very large or very small heads. A single number representing head size was determined as the cube root of three linear measurements. Several characteristic EEG frequencies were determined for each subject by means of Fourier analysis. The data indicate that alpha frequency is significantly correlated with head size: larger heads tend to produce slower alpha rhythms. It was also shown that alpha frequency tends to be lower in all subjects above roughly age 60. Subjects above produced significantly less alpha rhythm than the younger group. It is suggested that analogies between brain waves and physical waves may explain a number of phenomena which are typical of EEG.

Adolescent↗
PubMed1975

[Effect of intermittent noise on the function of concentration maintenance (TAF) and the brain waves (author's transl)].

The effect of three different kinds of noise, having equal physical energy but different psychological load, was examined by the TAF-test and the brain waves. Thirty nine healthy male subjects aging from 19 to 34 were exposed to white noise of 80 dB (C) under the following three conditions: (1) continuous noise for ten minutes, (2) regular intermittent noise, consisted of one-minute noise and one-minute rest, for 19 minutes, and (3) irregular intermittent noise, consisted of one-minute noise and irregular rest period, for 19 minutes. In each condition, the duration of noise-exposure totals ten minutes. Before, during and after the noise-exposure, the TAF-test was given to the 23 subjects out of 39, and the brain waves were recorded from the rest 16 subjects. The changes of TAF-L and alpha wave appearance were compared. The results obtained were as follows. 1. All three kinds of noise-exposure caused significant lowering of the function of concentration maintenance, especially in the latter half period of the noise administration. 2 Lowering of the function of concentration maintenance due to the irregular intermittent noise-exposure was greater than that due to the regular intermittent noise-exposure. 3. As to the continuous noise-exposure, appearance of the alpha wave decreased significantly in the 9th to 10th minute of noise administration and in the 1st min. after the exposure, while it increased in the 18th to 22nd min. after the exposure. 4. Exposure to the regular intermittent noise resulted in a significant decrease of the alpha wave appearance at the latter half of the noise administration, which continued after the exposure. 5. Exposure to the irregular intermittent noise caused a significant decrease of the alpha wave appearance after the middle period of noise administration. 6. Comparing the regular intermittent noise and irregular one, the latter brought about stronger alpha-blocking during the noise administration, but earlier restoration after the exposure. These results indicate that the influences of noise as a stressor differ not only by the amount of its physical energy but also by the condition of its generation, and that the differences of on-off effect on the brain activities based on regular or irregular intermittent noise were grasped by the changes of the function of concentration maintenance and the alpha wave appearance.

Adult↗
PubMed1976

Alpha brain wave production as an interpolated task in a Brown-Peterson paradigm.

Rehearsal, backward counting, and production of alpha brain-waves were used as interpolated tasks in a Brown-Peterson paradigm to determine their effect upon verbal retention. A within-subjects design was used in which trained subjects were told on a given trial either to produce alpha rhythm, mentally rehearse, or count backward following presentation of a CCC trigram. Results for the backward-counting condition duplicate, for the retention intervals used, the shape of the classic Peterson and Peterson forgetting curve but indicate little loss of memory in either the rehearsal or alpha conditions. No siginificant difference was found between the alpha production and rehearsal conditions.

Alpha Rhythm↗
PubMed1991

Neural mechanisms underlying brain waves: from neural membranes to networks.

In this review, a number of experimental findings and theoretical concepts that have led to new insights into the mechanisms underlying brain waves are presented. At the cellular level, the new evidence that certain types of neuron have intrinsic oscillatory properties that may underlie rhythmic EEG activities is discussed. In particular, the question of whether spindle oscillations are autonomous or input-dependent is addressed. At the neural network level, the main circuits of the thalamus and cortex that are responsible for the occurrence and modulation of spindles and alpha activity are described. In addition, the properties of rhythmic activities outside the alpha band are considered, particularly in relation to the prominent beta activity of the visual cortex. At the theoretical level, the possibility that neural networks may behave as complex dynamic systems with the properties of deterministic chaos is discussed. Finally, the fact that brain rhythms may have functional implications for the working of neural networks is examined in relation to 2 cases: the possibility that oscillations may subserve a gating function, and that oscillations may play a role in the formation of assemblies of neurons that represent given stimulus patterns.

Alpha Rhythm↗
PubMed1990

Stationarity and normality of distribution of rat cortical brain waves.

Establishing the stationarity and statistical distribution of potentials recorded from the nervous system is crucial for the application of frequency analysis. Both parameters were determined in the electrocorticograms of six adult Wistar rats during wakefulness and desynchronized sleep, during both of which desynchronization prevails. Stationarity of the signals was found to occur during at least 20 s in both states of the wakefulness-sleep cycle. A normal distribution was also found for at least 6.7 s. These findings provide strong support for the use of frequency analysis of brain waves as a reliable method to quantify neural electro-oscillograms.

Animals↗
PubMedDate not supplied

Brain waves.

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Attitude of Health Personnel↗
PubMed1991

Evidence for slow brain waves: a dynamical approach.

Various techniques of non-linear dynamics have been applied with success to EEG data and have provided a new insight into brain dynamics. Among these the 'recurrence plot' is a powerful tool for revealing the presence of drift or periodicities and is easily obtained in the framework of a non-linear dynamical analysis. When this analysis is applied to the EEG recorded from a patient suffering from Creutzfeldt-Jakob disease one observes the presence of slow periodicities of the order of 58 sec. We suggest that the recurrence plots are powerful tools for discovering hidden periodicities of EEG as well as the degree of stationarity of brain activity.

Brain↗
PubMed1976

Brain wave components of the contingent negative variation in humans.

In a contingent negative variation paradigm with two stimuli paired at an interstimulus interval of 4 seconds, two distinct waveforms having functional and topographic differences are observed. An early wave is maximal over the frontal cortex and is elicited by the warning stimulus. A later wave, maximal over the motor cortex, precedes the imperative stimulus and is identified with preparation for motor response.

Brain↗
PubMed1975

[Neurophysiology of hypnosis. The suggestive process and contributions of the learned control of brain waves].

The contribution that neurophysiological examination, subordinate to psychodynamic analysis, can bring to the investigation of facts and results in the therapeutic application of hypnosis is discussed. Phenomena with a suggestive background are analysed, particularly those of ideomotor transformation with reference to prereflective though (Polanyi & Dyer). A special case is represented by phobic-obsessive disturbances. Here analysis of the process of ideative reinforcement must take account of the untranslatability of certain linguistico-syntactic connotations at this level. The part played by sensorimotor EEG biofeedback training in practical therapeutics is also examined.

Cerebral Cortex↗