Ihre Suche

The perception of posture in man is made possible by the information of the vestibular organs, the visual system, the proprioception and the blood volume distribution. The present study examined the cerebral blood flow velocity (CBFV) and the fluid volume of the thoracic cavity under different pressure conditions and their effects on the perception of posture. Changes in blood flow velocity were measured by transcranial Doppler sonography (TCD), and changes in the blood volume distribution of the upper torso were registered by impedance plethysmography. The results indicated that the cerebral blood flow volume and the thoracic blood volume changed in the same manner. Lower Body Positive Pressure (+30 mmHg) led to an increase in central volume and CBFV. During the Lower Body Negative Pressure Treatment (-30 mmHg), the central blood volume and the cerebral blood flow velocity decreased while venous pooling occurred. Additionally, the changes in both parameters were associated with an altered posture perception. The correlations between the SHP and the two physiological parameters cerebral blood flow velocity and fluid shift in the upper thorax indicate that the fluid shift in the thoracic cavity was more closely related to the SHP than to the changes in cerebral blood volume.

Sferics are weak, naturally occurring electromagnetic fields related to specific weather conditions. There are some hints that these signals might be responsible for certain complaints that are often described as "weather sensitivity syndrome." The study's purpose was to find out whether humans, when exposed to simulated sferics, can consciously perceive any kind of psychophysiological changes. 63 subjects were trained within a simple learning paradigm to discriminate between phases where simulated sferics were present or absent. They were reinforced for each correct decision out of 80 judgements by means of acoustic signals. A reward of 100 German marks was pledged to the participant who would achieve the best result of the total sample. The total number of correct judgements did not differ from a random run and no learning occurred. Subjects who reported fewer bodily complaints in their recent past had higher scores in the discrimination task.

Many headache patients believe that weather changes act as pain triggers. Therefore, the present study investigated the psychophysiological influence of an indicator of atmospheric instability, Very Low Frequency (VLF)-sferics, on 32 subjectively weather-sensitive women suffering from migraine attacks and/or tension-type headaches. It was analyzed if sferics exposure is able to induce electrocortical changes as well as headache symptoms. The subjects, who had been divided into two groups, participated in a sferics simulation study. The experimental group (n = 16) underwent a ten-minute exposure to 10kHz-sferics impulses followed by 20 minutes without treatment in order to examine possible prolonged sferics effects. The control group (n = 16) received no treatment. As dependent measures, EEG spectral power was compared between the two groups at six electrode sites (F3/F4; P3/P4; O1/O2). Sferics exposure provoked increases in absolute alpha and beta power during the treatment. The alpha power enhancement was still present at parietal sites at the end of registration (20 minutes after the end of exposure). The stimulation did not induce headache symptoms.

22 believers and 20 skeptics of extrasensory perception (ESP) participated in a telepathy experiment. Subjects were asked to judge the covariation between transmitted symbols and the corresponding feedback given by a receiver. Believers overestimated the number of successful transmissions ('hits'). Skeptics were characterized by accurate hit judgments. For believers, positive correlations between hit-responses, their heart rates, and their experienced arousal were found. In addition, subjective arousal was positively associated with the hit estimates given at the end of the experiment. This response pattern was absent in the group of skeptics. It is concluded that covariation bias as a psychophysiological concept plays an important role in the maintenance of paranormal belief.

A previously recorded electromagnetic impulse of natural origin, a 10 kHz-sferic, was simulated and presented to 20 subjects. The magnetic component of the signal with a maximum field amplitude of 50 nT and a duration of 500 microseconds was applied over a duration of 10 minutes with a pulse repetition rate that varied statistically between 7 and 20 Hz. After sferics exposure, an additional 20 minutes without treatment were recorded in order to examine possible prolonged effects of sferics stimulation. The control group (n = 20) received no treatment. As a dependent measure, electrocortical changes throughout the course of the experiment were determined by means of EEG spectral analysis and compared between the two groups. Sferics exposure provoked increases in alpha and beta power. The effect was present during stimulation and continued for 10 minutes after the end of treatment. A longer lasting influence of sferics exposure was displayed by subjects with a high degree in weather sensitivity, somatic complaints, and neuroticism, who continued to stay on an enhanced alpha power level until the end of registration (20 minutes after the end of exposure). With these results a general electrocortical sensitivity towards sferics as well as individual differences in sferics reactivity could be demonstrated.

The present study investigated psychophysiological responses to paced respiration of different frequencies. Twenty men and 20 women (mean age: 24.3 years) underwent five breathing conditions (paced with 0.15 Hz, 0.20 Hz, 0.25 Hz, 0.30 Hz, and unpaced), each lasting 5 min. As dependent physiological measures heart period, and different heart period variability (HPV) parameters were assessed. Psychological variables consisted of mood estimates as well as rated accuracy and effort to follow the pacing rhythm. HPV decreased with higher breathing frequencies, under paced and unpaced conditions, whereas mood ratings did not change. Subjects indicated more effort and less accuracy in following the pacing signal, the more its frequency differed from their spontaneous breathing frequency. The comparison of a spontaneous breathing condition with a frequency-matched paced condition revealed that pacing per se provoked a reduction in heart period. Because this decrease was not accompanied by changes in any of the HPV frequency components, their validity as measures of autonomic control needs to be questioned.

The present study was carried out to determine the inhibitory cortical processes induced by changes in hemodynamics. Previous experiments in humans conducted in our laboratory have shown that there is a close relationship between posture and delta and theta EEG activity. The most pronounced effects were obtained during the 6 degrees head-down tilt (HDT) position. In space medicine the HDT procedure is very frequently employed to simulate micro-gravity and to determine the neurohormonal counter-regulations evoked by the expansion of central volume. Twenty male subjects spent 23 h in bed in 6 degrees HDT and 23 h in 6 degrees HUT (head-up tilt) positions during which EEG (frontal, central, parietal, occipital), startle responses, and reaction-times were measured every 2 h (from 10:00 h till 20:00 h). The effects of cardiovascular deconditioning (CD) regularly occurring after HDT were assessed by examining orthostatic tolerance and the physical work capacity (bicycle ergometry). As expected, 23 h HDT led to more pronounced CD than HUT. Spectral power analyses of EEG revealed increases in delta and theta frequency hands similar to those found during HDT in previous EEG studies. In addition, subjects responded more slowly (S1-S2 reaction-time task) during HDT as compared with HUT bedrest. The influence of HDT on startle response, however, was not in keeping with the initial hypothesis (i.e. dampening of reflex activity). The EEG data and the sensorimotor performance indicated that the body fluid shift towards the thoracic cavity induced by HDT resulted in signs of cortical inhibition. In addition to neural mechanisms, other processes must be postulated which are closely related to the counter-regulation evoked by the varying body positions.

Sferics are electromagnetic impulses generated by electrical discharges during thunderstorms (lightning). One category is comprised of very low frequency electromagnetic waves, traveling over distances up to a thousand kilometers. Sferics have been shown to affect biological responses such as pain syndromes, reaction times, and power in the alpha band of the EEG. In the present study, in which 100 subjects took part, sferics have been studied in their relation to performance on a forced-choice extrasensory perception (ESP) task and to several secondary variables. The general finding is a negative correlation between ESP performance and sferics activity around the time of the session, most notably 24-48 hours prior to the session. Secondary variables appear to modulate this correlation, as has been found in previous research on sferics: the correlation tended to be stronger for persons who scored lower on Neuroticism and higher on the Openness scale of a Five-Factor Personality Questionnaire.

In a previous study a negative correlation was found between the natural sferics activity and scores on an ESP task. We attempted a replication in three studies with 37, 100, and 68 participants. In these studies ESP scores and the level of sferics activity were not significantly correlated. The result for all combined data is significant but with a quite low effect size. Other trends in the data could not be confirmed.

Many patients with migraine believe weather is a trigger for their headaches. The objective of this study was to determine if very low frequency sferics, pulse-shaped electromagnetic fields originating from atmospheric discharges (lightning), are precipitating factors. The occurrence of sferics impulses is characterized by a daily, as well as an annual, periodicity and is thought to be associated with various pathological processes. The diaries of 37 women suffering from migraine and tension-type headaches were analyzed over a period of 6 months and correlated with daily sferics activity and other weather phenomena in the area of Giessen, Germany. From October through December (autumn), sferics activity was correlated with the occurrence of migraine (r = 0.33, P<.01); however, there was no correlation in July and August (summer), when the thunderstorm activity had been very intense. In summer, tension-type headaches were associated with other weather parameters such as temperature (r = 0.36, P<.01) and vapor pressure (r = 0.27, P<.05).

Although it is known that there are fundamental personality differences in the behavioral responses to emotional stimuli, traits have scarcely been investigated in this context by means of functional imaging studies. To maximize the variance with respect to personality, the authors tested 12 control subjects and 12 subjects who had sadomasochistic experiences with respect to the relationship between J. A. Gray's (1970) personality dimensions, the behavioral approach system (BAS) and the behavioral inhibition system (BIS), and brain activity in regions of interest. The BIS was associated with activity in numerous brain areas in response to fear, disgust, and erotic visual stimuli, whereas few associations could he detected between the BAS and brain activity in response to disgust and erotic stimuli.

Latent inhibition (LI) is an important model for understanding cognitive deficits in schizophrenia. Disruption of LI is thought to result from an inability to ignore irrelevant stimuli. The study investigated LI in schizophrenic patients by using Pavlovian conditioning of electrodermal responses in a complete within-subject design. Thirty-two schizophrenic patients (16 acute, unmedicated and 16 medicated patients) and 16 healthy control subjects (matched with respect to age and gender) participated in the study. The experiment consisted of two stages: preexposure and conditioning. During preexposure two visual stimuli were presented. one of which served as the to-be-conditioned stimulus (CSp + ) and the other one was the not-to-be-conditioned stimulus (CSp - ) during the following conditioning ( = acquisition). During acquisition, two novel visual stimuli(CSn + and CSn - ) were introduced. A reaction time task was used as the unconditioned stimulus (US). LI was defined as the difference in response differentiation observed between preexposed and non-preexposed sets of CS + and CS - . During preexposure, the schizophrenic patients did not differ in electrodermal responding from the control subjects, neither concerning the extent of orienting nor the course of habituation. The exposure to novel stimuli at the beginning of the acquisition elicited reduced orienting responses in unmedicated patients compared to medicated patients and control subjects. LI was observed in medicated schizophrenic patients and healthy controls, but not in acute unmedicated patients. Furthermore LI was found to be correlated with the duration of illness: it was attenuated in patients who had suffered their first psychotic episode.

fMRI studies have shown that the perception of facial disgust expressions specifically activates the insula. The present fMRI study investigated whether this structure is also involved in the processing of visual stimuli depicting non-mimic disgust elicitors compared to fear-inducing and neutral scenes. Twelve female subjects were scanned while viewing alternating blocks of 40 disgust-inducing, 40 fear-inducing and 40 affectively neutral pictures, shown for 1.5 s each. Afterwards, affective ratings were assessed. The disgust pictures, rated as highly repulsive, induced activation in the insula, the amygdala, the orbitofrontal and occipito-temporal cortex. Since during the fear condition the insula was also involved, our findings do not fit the idea of the insula as a specific disgust processor.

fMRI studies have shown that the perception of facial disgust expressions specifically activates the insula. The present fMRI study investigated whether this structure is also involved in the processing of visual stimuli depicting non-mimic disgust elicitors compared to fear-inducing and neutral scenes. Twelve female subjects were scanned while viewing alternating blocks of 40 disgust-inducing, 40 fear-inducing and 40 affectively neutral pictures, shown for 1.5 s each. Afterwards, affective ratings were assessed. The disgust pictures, rated as highly repulsive, induced activation in the insula, the amygdala, the orbitofrontal and occipito-temporal cortex. Since during the fear condition the insula was also involved, our findings do not fit the idea of the insula as a specific disgust processor.

The understanding of individual differences in responses to disgusting stimuli is important to gain more insight into the development of certain psychiatric disorders. The aim of this study was to investigate conditioned disgust responses, its potential overlap with conditioned fear responses (CRs) and the influence of disgust sensitivity on blood oxygen level-dependent responses. Yet even though current studies report evidence that disgust sensitivity is a vulnerability factor, the knowledge about the underlying neural mechanisms remains very limited. Two groups were exposed either to a disgust- or a fear-conditioning paradigm. Using functional magnetic resonance imaging, we identified a conjoint activated network including the cingulate cortex, the nucleus accumbens, the orbitofrontal cortex, and the occipital cortex within the disgust- and the fear-conditioning group. Moreover, we report evidence of increased insula activation in the disgust-conditioning group. In addition, functional connectivity analysis revealed increased interconnections, most pronounced within the insula in the high disgust sensitivity group compared with the low disgust sensitivity group. The conjunction results suggest that the conditioned responses in disgust and fear conditioning recruit the same neural network, implicating that different conditioned responses of aversive learning depend on a common neural network. Increased insula activation within the disgust-conditioning group might be attributable to heightened interoceptive processes, which might be more pronounced in disgust. Finally, the findings regarding disgust sensitivity are discussed with respect to vulnerability factors for certain psychiatric disorders.