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R Weitkunat

Publications and source records attributed to R Weitkunat.

8 recordsLinked to original sources
PubMed1991

Individual differences in cortical evoked potentials as a function of heartbeat detection ability.

Much work has been done to assess individual differences in the ability to detect visceral activity, and most of this work has focused on heartbeat detection ability. This experiment attempted to determine if some underlying cortical event is associated with heartbeat detection ability, and further, to assess whether this cortical event is lateralized to the right hemisphere. Event-related cortical potentials, time-locked to the EKG R-wave and averaged over 400 samples, were studied at Fz, Cz, F7, and F8 in 12 subjects. The primary dependent measure of heartbeat detection accuracy was the standard deviation of the mean temporal latency, measured from peak EKG R-waves to the subjects' report of physical sensation of heartbeats. A significant relationship was found between the amplitudes of event related potentials (ERPs) in the right hemisphere and heartbeat detection accuracy.

Adolescent↗
PubMed1990

Cortical initiation of phasic electrodermal activity.

In order to investigate the role of the cerebral cortex in elicitation of spontaneous electrodermal responses (EDRs), electrocortical activity (EEG) preceding peripheral fluctuations was investigated. During one 30-min session, subjects imagined arousing situations. EEG and EDR average waveforms were computed with respect to the EDR maxima. In Grand Average EEG waveforms, transient activity preceding EDR onset at about 2.3 seconds, lasting for about 1 s, was observed. The main power of this phasic event was in the alpha frequency band. Digital filtering of EEG waveforms supported the assumption of a visceral control process at cortical level, responsible for triggering peripheral EDRs. Whereas the phenomenon occurred slightly earlier frontally than centrally, it was strongest at the vertex. The possible interpretation of this electrocortical phenomenon, related to the evocation of electrodermal responses, as a final common pathway of different EDR generating systems is discussed.

Adult↗
PubMed1990

Enhancement of heartbeat-related brain potentials through cardiac awareness training.

Heartbeat synchronous potentials were found to be sensitive to differences in perceptual accuracy. Since heartbeat perception can be improved using appropriate training procedures, increased ability to perceive cardiac performance should also influence heartbeat-related potentials. In the present study, subjects in either of two groups had to press a button immediately after the occurrence of a heartbeat-feedback tone. Whereas the first group was given acoustical heartbeat-feedback throughout the entire training, the second group was provided with tone signals that became fainter during the course of the training phases. The better posttraining performance in heartbeat perception of the group receiving full-intensity feedback was also reflected in the evoked potentials. They differed markedly before and after training, especially between 250 to 400 ms (after the EKG-R-wave), the biggest effect being at Fz and F7. The findings are interpreted as the brain electrical reflection of an increased perception susceptibility to a cardiovascular signal occurring at about 200 ms after the R-wave.

Adult↗
PubMed1990

[Cardiodynamic determinants of heart perception].

Subjective perception of one's heartbeat is augmented by psychological factors (stress, fear) as well as by physiological influences (e.g., physical work). It is still unclear on which cardiac or circulatory parameters the "signal" for cardiac perception is based. In this study, the relation between cardiac performance and the ability to perceive one's heartbeat was investigated. Sixteen healthy subjects (8 female, 8 male, aged from 21 to 31 years) participated. Cardiac activity was varied by a combination of passive tilt and physical work on a bicycle ergometer. Subjects had to perform physical work (0, 25, 50, 75, 100 W) on the bicycle at seven different angles (90 degrees, 75 degrees, 60 degrees, 45 degrees, 30 degrees, 15 degrees, 0 degrees). A cardiac perception test was carried out after each load. The following cardiodynamic parameters were measured: stroke volume, contractility, and heart rate. The mean correlation coefficient between cardioceptive performance and cardiodynamic parameters was .62 for stroke volume, .45 for contractility, and .12 for heart rate. Obviously, a remarkable relation exists between the mass and--to a lesser degree--the velocity of ejected blood and cardiac perception. From this we infer, tentatively, that the subjectively perceivable heartbeat stimulus is generated by mechanical events that occur close to the left ventricle.

Adult↗
PubMed1989

[Changes in the cardiac dynamics in passive tile to the supine position--impedance cardiography measurements].

Passive tilt is an effective means to manipulate cardiodynamic processes. While there is a large amount of literature available concerning cardiac function with upright tilt, passive tilt into the supine position is poorly investigated. There is evidence that adapting processes to the new position do not show analogy in both conditions. In this study we investigated cardiodynamic changes occurring with passive-graded tilt from the upright position to 20 degrees headdown tilt. Twenty healthy students of both sexes participated in the study. Using impedance cardiography combined with phonocardiography it was possible to acquire stroke volume, heart rate, Heather index, and systolic time intervals. The whole procedure was repeated to test the reliability of impedance data. There was no steady augmentation of stroke volume. Between 90 degrees and 60 degrees stroke volume remained stable and showed only little change between 60 degrees and 30 degrees. Between 30 degrees and the supine position there was a steep increase of stroke volume. Tilting into the upright position apparently has a different effect. The onset of heart rate decline preceded the increase of stroke volume. It is concluded that only little changes of stroke volume/preload are necessary to induce vagal response. In the 30 degrees position both cardiac output and Heather index were minimal; this may be due to decreased sympathetic output. Systolic time intervals showed volume dependancy. Correlations between the first and second part of the study were high for all variables.

Adult↗
PubMed1986

From the heart to the brain: a study of heartbeat contingent scalp potentials.

Heartbeat perception has become the most widely studied example of visceral perception. In the present study scalp potentials contingent to the visceral event "heartbeat" were investigated. Scalp potentials, averaged time-locked to the EKG-R-wave, were studied at Fz, Cz, and Pz under four conditions: resting (baseline), heartbeat discrimination task, signal detection task, and heartbeat discrimination task after physical exercise. 22 subjects were assigned to the two groups "good" and "poor" perceivers, according to their performance in an initial heartbeat perception test. Event related potentials (ERPs) of "good" perceivers were more stable across conditions than those of "poor" perceivers. Peak latency within the range of 200 to 300 ms differed significantly between conditions. A principal component analysis performed on the ERP averages extracted five components. Subsequent ANOVAs across factor scores yielded significant main effects for the "groups" factor, experimental conditions and electrode sites. The strongest effects occurred over the frontal region in the latency range of 250-400 ms (following the EKG-R-wave). These were found to be not due to artifactual EKG influences.

Adult↗