PubMed Health⌕ Search

Biomedical subjects

W Scheuler

Publications and source records attributed to W Scheuler.

27 records · Page 2Linked to original sources
PubMed1979

[A contribution to the psychophysiology of infantile dysmegalopsy (author's transl)].

A 9 year old boy was able to evoke microptic experiences voluntarily. Clinical and historical signs of minimal brain dysfunction were present. An epileptic etiology could neither be proven nor ruled out. Synchronized EEG- and Video recording allowed us to analyze the EEG and the corresponding behavior by using sequential spectral analysis of the EEG data. Coinciding with a progressive increase in rhythmic 6-7 cps. activity we observed a behavior which appeared to correspond to a state of narrowed attention. He signalized the onset of a micropsy a few seconds after the transition from this pattern into one which showed a relative voltage decrease and the reappearance of some alpha-activity. The end was signalized by him coinciding with the recurrence of normal waking activity. Our findings--like those of others--suggest that the gradual development of hypnagogic phenomena is bound to a state of lowered vigilance. The reappearance of alpha activity and the voltage decrease seem to represent an unstable intermediary state with partial arousal preceding the restitution of normal wakefulness. Since the onset of the micropsy was signalized only after manifestation of the intermediary EEG-state, we conclude that partial arousal is a prerequisite for giving an indication of hypnagogic experiences in a quasi retrospective manner.

Arousal↗
PubMed1978

[On the effect of the antidepressant viloxazin on EEG and optimization of the system driver-vehicle-road (author's transl)].

The effects of a single dose of 100 mg 2-[(o-ethoxyphenoxy)-methyl]-morpholine hydrochloride (viloxazin) on EEG and optimizing control behaviour of drivers were investigated under double-blind conditions in 5 male subjects with many years' driving experience. The study was carried out on a special test course using a car equipped with measuring devices. The following signals were recorded: EEG and EOG, driving speed, steering torque, steering angle and angle rate, longitudinal and lateral acceleration, and yaw rate. As evaluated by means of spectral analysis with a subsequent principal component analysis the EEG showed an increase of the power in alpha- and beta-frequencies indicating a drug induced decrease of EEG vigilance. In correspondence the optimization of the system driver-vehicle-road was reduced indicating an impairment of the driver's control behaviour.

Adult↗
PubMed1976

[Psychophysiological studies of EEG, operational performance and the dynamics of vigilance regulation. I. The EEG during performance of Brickenkamp's attention-concentration test (test d 2) (author's transl)].

During the performance of the d 2 test developed by Brickenkamp (standardized test of attention and concentration), occipital EEG activity was registered telemetrically in 10 male students aged 25 to 32 years. Simultaneously, the pencil markings performed by the subjects, indicating the time course of their pattern recognition and discrimination, were recorded by means of a piezo-electrical transducer. The EEG behavior during test performance was evaluated by serial spectral analysis. The analysis of the EEG parameters derived from it (total power, absolute and relative alpha-power) showed that there is a relationship between these EEG measures reflecting the regulation of cortical vigilance and the error rate in the concentration test. While subjects with low error rate present a heightening of cortical arousal focused in the right occipital area, subjects with higher error rate tend to have a higher degree of general cortical activation.

Adult↗
PubMed1976

[Psychophysiological studies of EEG, operational performance and the dynamics of vigilance regulation. II. EEG activity and reactivity during tracking performance in a control loop with varying degrees of difficulty (author's transl)].

In ten male students the EEG occipital activity was recorded during a visuo-motor task consisting of pursuit-tracking. The degree of task difficulty varied systematically depending on the modification of the transfer function of control element dynamics. The EEG data were evaluated by serial spectral analysis. The distribution functions of the total power estimates and their minima and maxima reflect the dynamics of the regulation of cortical vigilance and permit to differentiate the degree of effort which corresponds to the varying degree of task difficulty. The study of task-irrelevant acoustically evoked potentials showed that with increasing cortical activation the amplitudes of N1-P2 and P2-N2 are diminished. These results might suggest that evoked potentials induced by task-irrelevant stimuli can serve as indicators of the neuronal capacity available for information processing that is not task-oriented.

Adult↗
PubMed1976

[Signal analysis of EEG-changes induced by nomifensin - a new antidepressant (author's transl)].

Ten healthy volunteers received a single oral dose of 100 mg nomifensive, a new antidepressant (tetragtdriusiqyubikube deruvatuve; Hoe 36-984). The drug-induced effects on the EEG were compared with those of placebo. The statistically proved results show that nomifensine causes a distinct shift in vigilance with two different partial processes. After an initially occurring stabilization of the dominant alpha-frequency there appears a polyrhythmic disintegration of the alpha-rhythm with increase of slower and faster frequencies. At the same time a shifting takes place within the beta-range with increasing of 23.5-32.0 Hz-components. Accordingly it is evident that nomifensine results in a typical pharmaco-electroencephalographic profile.

Alpha Rhythm↗
PubMed1975

[Influence of repetition rate and pause upon the cortical potential evoked by various acoustic stimulation in man (author's transl)].

In agreement with earlier experiments an increase of amplitude of the medium components (80-250 ms: Non-Pon) with decreasing repetition rate or increasing interval between the stimuli (sinusoidal tones, white noise, craftsman noise) is observed. There is no influence of the variable intervals upon the off-effect, if sinusoidal tones and white noise are used. A small increase of the amplitude difference Noff-Poff results if bursts of craftsman noise are used for stimulation. The amplitude of a peak in the range 300-400 ms which can be regarded approximatively as the peak of the long lasting dc-component, related to the positive peak (Pon) around 200 ms shows also an increasing tendency if the interval between stimuli is enlarged. Pon itself is augmented if related to the preceding section before stimulus on-set. Therefore the increase of the slow component expresses only an increase of the positive component Pon or is based upon a dc-shift which is added to the preceding section as well as to the range of the dc-component beginning around 300 ms after stimulus on-set. Using only sinusoidal tones a reduction takes place of the amplitude of the potential evoked by a tone of constant duration if the silent pauses are smaller than 2500 ms. If the pause preceding a tone of constant duration is reduced down to 300 ms the decrease of the amplitude is around 50-60%. The amplitude of the off-effect however is not affected. Only if related on the positive component Pon the slow component shows a small decrease. If related on the preceding section there is no change caused by different pauses preceding a tone of constant duration. Both, the latency of on- and off-components is also not influenced by the variable pause. Only the peak of the slow component shows a shift in the way that there is a maximum if the duration of the pause corresponds to half of the interval. In this case there is also a clear maximum of the amplitude of the potential evoked by the tone of variable duration. The results throw some light upon the different origin of the components of the evoked response and the overlapping of dc-shifts.

Acoustic Stimulation↗
PubMedDate not supplied

EEG sleep activities react topographically different to GABAergic sleep modulation by flunitrazepam: relationship to regional distribution of benzodiazepine receptor subtypes?

Spectral analysis was performed to study the response of various EEG sleep activities to a modification of GABAergic sleep regulation by flunitrazepam. We observed sleep stage- and sleep cycle-dependent differences in the topographic distribution of the reactions. An increase in power density was found in the frontal regions for the alpha 2 and sigma 1 frequency band whereas a decrease in power density was emphasized in the posterior regions for the delta and alpha 1 frequency band. These topographic differences might be related to the regional distribution of benzodiazepine receptor subtypes.

Adult↗