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Biomedical subjects

P Ullsperger

Publications and source records attributed to P Ullsperger.

At least 55 records · Page 3Linked to original sources
PubMed1986

Effect of whole-body vibration with different frequencies and intensities on auditory evoked potentials and heart rate in man.

Auditory evoked brain potentials (AEP) and electrocardiogram (ECG) were recorded from 9 healthy male subjects during sinusoidal whole-body vibration exposure (WBV) in the longitudinal (+/- az) direction with four frequencies (1 Hz, 2 Hz, 4 Hz, and 8 Hz) and two intensities as well as under non-WBV conditions. The sequences of the different experimental conditions were arranged according to a 9 X 9 Latin Square design. The sound of the electrohydraulic vibrator was masked by a constant noise level. A subtraction technique was used to eliminate vibration-synchronous activity contaminating the electroencephalogram. The AEP amplitude N1-P2 revealed systematic effects of different WBV frequencies and intensities. The amplitude decreased along with an increase in intensity (16 dB) by about 10 per cent. It diminished increasingly with a monotonic trend in the order non-WBV, WBV 8 Hz, WBV 4 Hz, WBV 2 Hz, and WBV 1 Hz. The interbeat-interval histograms computed from the ECG exhibited the highest mean values at MBV of 1 Hz, high intensity, and the lowest ones at WBV of 4 Hz, high intensity. The AEPs are reaffirmed as an informative measure for studying the WBV effect on central nervous information processing, although the modes of action are not yet fully known. Efferent influences on the acoustic input, cross-modality interaction, sensory mismatch, and changes of central nervous activation level are discussed as potential mechanisms.

Adolescent↗
PubMed1985

[The P300 component of the event-related brain potential as an indicator in the study of information processing].

Event-related bioelectrical brain activity plays an important role in psychophysiological investigations of mental processes. One of the so-called endogenous components of ERP, the P300, occurring in the time range from 300 ms to 800 ms after stimulus presentation accompanies the selective call on cognitive processing of stimulus information. An overview of some influencing factors and of hypotheses according functional significance of P300 is given. Although functional significance of P300 is only partly known there are interesting possibilities of application, e.g. in Neurology, Psychiatry and Occupational medicine.

Arousal↗
PubMed1983

Changes in EEG power density spectrum during static muscle work.

Changes in parameters of the EEG power density spectrum were demonstrated in four healthy male subjects during fatiguing static muscle contractions (M. biceps brachii dexter). For the following EEG frequency bands (delta 1-4 Hz, theta 4-8 Hz, alpha 8-13 Hz, beta 13-20 Hz), the relative power and the peak frequencies were determined. A significant increase in the alpha peak frequency was observed during muscle work. This trend was evident in both the central leads (C3-A1, C4-A1) and the occipital (O1-A1), particularly when the subjects had their eyes closed. These changes in peak frequency might be connected with an increase in central nervous activation.

Adult↗
PubMed1983

Hemispheric differences in VEP elicited by mental arithmetic and tachistoscopically presented spatial transformation tasks.

Recent studies have furnished evidence of hemispheric asymmetry in the EEG and event-related potentials in man. Face-validated tasks as verbal and nonverbal ones (A: mental arithmetic; B: detection of a target in the hand of a manikin in different positions) were tachistoscopically presented to check side differences of VEP parameters in 5 healthy right-handed subjects. The EEG was recorded from C3, C4, P3 and P4 referenced to linked ears. The mean peak latencies of averaged VEPs were P1: 107 ms, N1: 142 ms, P2: 203 ms, N2: 265 ms, P3: 357 ms. No consistent treatment effects were obtained for peak latencies. Regardless of side differences, the attention related VEP amplitudes P1-N1 and N1-P2 were higher in A. Rightleft differences were found to be higher for visual-spatial transformation, except P2-N2 amplitude. The asymmetry of amplitudes suggests a higher activity of the right hemisphere in B. A possible description of dynamic variations due to learning and changes of strategy during repetitive mental activity by means of changes in EP asymmetry will be of interest for further investigations.

Adult↗
PubMed1981

Polarity histogram - a supplementary method for evoked potentials analysis.

The aim of this study was to evaluate how far the variations in the P300 amplitude of the event-related potentials (ERP) are related to the changes in the frequency of P300 occurrence from the polarity histogram. ERP from Cz (10/20 system) in a task of counting one of two different stimuli ("soft" and "loud" tones) presented in a Bernoulli sequence were recorded. A control situation, i. e. stimuli presentation while the subject is reading a book, was also included. For each subject the two situations were presented according to a completely balanced orthogonal experimental design. The analysis of variance showed statistically significant effect of the task, as well as of the experimental period of the P300 amplitude. For each subject the differences in the P300 amplitudes and the corresponding frequencies of occurrence between the two situations were assessed. The results obtained showed that the changes in the frequency of occurrence are mostly associated with the mere presence of absence of P300. Therefore the polarity histogram provides information particularly valuable for the endogenous ERP components and permits quick identification of these components.

Adult↗
PubMed1980

On auditory evoked potentials and heart rate in man during whole-body vibration.

Auditory evoked brain potentials and heart rate were recorded from three healthy male subjects during sinusoidal whole-body vibration exposure in the longitudinal (+/- aZ) direction (two intensities: I1 = 0.57 ms-2 r.m.s., I2 = 3.2 ms-2 r.m.s., frequency: 4 HZ) and under no-vibration control conditions according to a change-over design. All conditions were performed at a constant noise level. The part of vibration-synchronous activity contaminating the averaged evoked potentials (AEP) was eliminated by means of a subtraction technique. The AEP amplitude N1--P2 showed a significant decrease during vibration exposure; this decrease was slightly greater during I2 than during I1. Except for a shortening of P2 due to vibration of I1, the peak latencies did not change significantly. The heart rate increased when subjects were exposed to vibration at I1; there were interindividually opposite significant changes under I2 exposure. Time effects and subject effects were also proved. The AEPs are considered to be an informative measure for studying the effect of vibration on central nervous information processing.

Acoustic Stimulation↗
PubMed1977

[Influence of static muscle tension on acoustically evoked brain potentials, changes in skin resistance and bioelectric muscle activity].

Auditory evoked brain potentials (AEP), galvanic skin responses (GSR) and auditory evoked bioelectrical muscular responses were recorded in 16 male human subjects during voluntary isometric contraction of m. triceps brachii dexter. The electromygraphically controlled strength of muscular innervation corresponded to 20, 30, 40 and 50% of the maximal voluntary contraction. The trials were organized according to a change-over design. The following results could be obtained: The stepwise increase of the strength of muscular innervation effected an increase of the mean amplitude of auditory evoked EMG responses. The N1-P2 amplitudes of the AEP decreased with increasing strength of muscular innervation. The mean amplitude of the auditory evoked galvanic skin response was not changed significantly by the strength of muscular innervation, however, the spontaneous changes in galvanic skin resistance increased monotonously. Habituation effects were evident regarding amplitudes of AEP and GSR. The results indicate that muscular activity affects sensory information processing.

Acoustic Stimulation↗
PubMed1976

[Activation-dependent characteristics of the electroencephalogram during visual information--processing: Results of an automatic interval analysis (author's transl)].

EEG signal from fronto-occipital derivation was recorded in 16 Ss during a mental performance test (modified "Konzentrations-Leistungs-Test" including four levels of performance). A balanced changer-over design was used. Interval histograms in four frequency bands (theta, alpha, beta-1 and beta-2 bands) were determined on the basis of peak detection. A total of 44 characteristics were derived and tested (multi-factor analyses of variance, multiple mean comparison and rank tests). Twenty eight of these characteristics were proved to be dependent on activation. In the visual information-processing performances chosen, it could be demonstrated that the intraindividual changes of the spontaneous EEG activity were related predominantly to the perceptual components of the performance. On the other hand, the influence of the performance rate and of the mental-arithmetic itself was of minor relevance. During higher activation an increase in the relative abudance of the theta-band activity was also observed.

Adult↗