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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.

This article examines the relation between the perception of one's own body position and the distribution of fluid along the subject's spinal (z-) axis. Two experiments are reported. The first one is a replication of the Vaitl et al. study [J. Psychophysiol. 27 (1997) 99] which has shown that changes in shifts of blood volume into or out of the thoracic cavity induced by lower body positive pressure (LBPP: +30 mmHg) or lower body negative pressure (LBNP: -30 mmHg) exerted on the lower body led subjects to feel tilted head-up or head-down, respectively. The second experiment was designed to differentiate between the influence of the otoliths and of the changes in fluid distribution on the perception of body position by means of a sled centrifuge in combination with LBPP and LBNP. In both experiments, changes in blood distribution within the thoracic cavity were measured by impedance plethysmography. Forty healthy volunteers (17 females) participated in experiment 1. They were positioned on the side (right-ear-down head position) on a tiltable board which the subject and the experimenter could tilt via remote control around the subjects' z-axis. Subjects were asked to rotate the board until they felt they were in a horizontal posture. The results clearly show that the perception of posture is influenced by the shift in blood distribution. During LBNP subjects perceived being tilted head-up, whereas LBPP led them feel tilted head-down. Thus, the results obtained in the 1997 study were replicated. Fourteen males volunteered in experiment 2. They were positioned on the sled on a centrifuge in the same manner as in experiment 1. The sled could be moved via remote control by both the subject and the experimenter. While the centrifuge rotated (omega=2 pi times 0.6 rotations per second) the subjects were asked to move the sled until they felt they were in a horizontal position. As in experiment 1, shifts in blood volume were induced by LBPP and LBNP. The distance between the binaural axis (position of the otoliths) and the centrifuge axis served as dependent measure indicating the subjective horizontal position. Due to the additional centrifugal forces exerted on the body the shifts in blood volume were more pronounced than in experiment 1 where only gravitational forces were produced. The changes in the perception of posture were influenced by both the otoliths and the fluid distribution in such a way that both interact in a compensatory manner. These results again corroborate the evidence that afferent inputs from the cardiovascular system play a major role in the perception of the body posture. This phenomenon of graviception needs to be further elucidated with respect to the origins of the afferent inputs and the site and type of graviceptors (mechanoreceptors) involved.

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.

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).

Very-low-frequency (VLF) atmospherics or sferics are pulse-shaped alternating electric and magnetic fields which originate from atmospheric discharges (lightning). The objective of the study was threefold: (i) to analyse numerous parameters characterizing the sferics activity with regard to their suitability for field studies, (ii) to identify meteorological processes related to the sferics activity and (iii) to investigate the possible association of sferics with pain processes in patients suffering from migraine- and tension-type headaches. Over a period of 6 months (July through December) the sferics activity in the area of Giessen (Germany) was recorded. Three sferics parameters were chosen. The number of sferics impulses per day, the variability of the impulse rate during a day and the variability in comparison to the preceding day were correlated with weather processes (thunderstorm, temperature, vapour pressure, barometric pressure, humidity, wind velocity, warm sector). Significant correlations were obtained during the summer months (July, August) but not during the autumn months (October, November, December). During autumn, however, the sferics activity was correlated with the occurrence of migraine-type headaches (r=0.33, P<0.01) recorded by 37 women who had filled out a headache diary over a period of 6 months (July–December). While the thunderstorm activity was very intense during July and August, no relationship between sferics and migraine was found. In summer, tension-type headaches were associated with meteorological parameters such as temperature (r=0.42, P<0.01) and vapour pressure (r=0.28, P<0.05). Although the sferics activity can explain a small percentage of the variation in migraine occurrence, a direct influence was more likely exerted by visible or otherwise perceptible weather conditions (thunderstorms, humidity, vapour pressure, warm sector, etc.) than by the sferics activity itself.

The magnitude of the startle eyeblink response is diminished when the startle-eliciting probe is shortly preceded by another stimulus. This so called prepulse inhibition is interpreted as an automatic sensorimotor gating mechanism. There is substantial support for prepulse inhibition deficits in subjects suffering from schizophrenia spectrum disorders and in psychosis-prone normals as well. Thus, prepulse inhibition deficits may reflect vulnerability on the hypothesized psychopathological continuum from “normal” to “schizophrenia.” The present experiment investigated the amount of prepulse inhibition in a sample selected for “belief in extraordinary phenomena,” an attitude related to measures of psychosis-proneness. Believers and skeptics were tested in an acoustic prepulse-inhibition paradigm. As expected, presentation of prepulses clearly diminished magnitude of startle response, with greatest inhibition effects gained by lead intervals of 60 and 120 msec. Patterns of response were identical for believers and skeptics, i.e., attitude towards extraordinary phenomena did not seem to be related to functional information-processing deficits as has been observed in psychosis-prone normals.

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.

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.

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.

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.

Neuropsychological research on temporal constraints of perception and motor performance can add important information to research on human behavior. Without considering temporal mechanisms of perceiving, generating, and updating information, brain mechanisms can never be fully understood. In this study temporal aspects of performance in psychophysical experiments on three different temporal levels (around 30 ms, 300 ms, and 3000 ms) were investigated in patients with acquired brain lesions and a control group without neurological deficits. The patients had acquired focal brain lesions in: anterior (pre-central) regions of the left hemisphere (with non-fluent aphasia), posterior (post-central) regions of the left hemisphere (with fluent aphasia), the left hemipshere in predominantly subcortical regions (without aphasia), or anterior (pre-central) or posterior (post-central) regions of the right hemipshere. Perception of temporal order (20 to 60 ms) was impaired in patients with left-hemispheric post-central lesions; repetitive voluntary action (300 to 500 ms) was affected mostly in patients with left hemi-spheric lesions, both pre-central and post-central; and a deficit in integrating (2000 ms to 3000 ms) information was most pronounced in patients with left and right pre-central lesions. These findings provide insight into the associations between different levels of temporal organisation and circumscribed regions of the neocortex.

OBJECTIVE: Comparison of low back pain (LBP) patients with and without fibromyalgia syndrome (FMS) with regard to affective distress. METHODS: Patients with LBP who had been admitted to various clinics in Germany were examined upon admission. Comparisons were done by dividing the patients into groups with and without signs of FMS. Additionally, both groups were compared after being matched according to sex, age, and pain severity. RESULTS: 15 out of 135 LBP patients met the American College of Rheumatology criteria for fibromyalgia. Patients with FMS showed remarkably higher levels of pain severity and affective distress. After controlling for different levels of pain severity, these pronounced differences disappeared. CONCLUSION: Affective distress is not a unique feature of FMS, but seem to be caused entirely by higher levels of pain severity.

Recent experiments have shown that somatic graviceptors exist in humans. Traditionally, extravestibular gravity information has been thought to originate from mechanoreceptors in the joints, muscles and skin. Experiments with normal, paraplegic and nephrectomized subjects revealed that the kidneys and the cardiovascular system are involved in providing truncal gravity information. The present study intends to determine the influence of shifts in body fluid, especially of the distribution of blood along the subjects' spinal (Z-) axis, on the perception of posture. To this end, the distribution of body fluids was altered by means of the technique of lower body negative and positive pressure (LBNP and LBPP). LBNP leads to venous pooling of blood in the legs, whereas LBPP prevents venous blood from pooling, increasing central volume. Changes in blood distribution were measured by segmental impedance cardiography for four body segments: the upper torso (thoracic cavity), lower torso (abdominal and pelvic region), thigh and calf. Seventeen healthy subjects (mean age: 27.3 years) participated in the experiment. They were positioned on the side (right-ear-down head position) on a tilt table which the subjects and the experimenter could tilt via remote control around an axis parallel to the subjects' visual (X-) axis. The experimenter set the initial tilt in total darkness to arbitrary angles while strictly alternating between head-up and head-down tilts. Subjects were then asked to rotate the board until they felt they were in a horizontal posture. Means and variances of eight pairs of settings were taken as a measure of the subjective horizontal posture (SHP). During LBNP (-30 mmHg), subjects perceived being tilted head-up, whereas LBPP (+30 mmHg) led them to feel tilted head-down. The results corroborate the hypothesis of an effect of the blood's mass on graviception and also indicate supplementary contributions of other visceral afferences.

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 was designed to examine the pattern of startle reflex modulation and autonomic responses for individuals high in animal or blood-injury fear when viewing pictures of their feared objects. Sixteen individuals in each fear group and 16 low-fear control individuals viewed 32 color slides depicting fear-relevant, unpleasant but fear-unrelated, neutral, and pleasant scenes. Free viewing times were assessed in a second phase of the procedure as an index of avoidance behavior. Exposure to pictures of feared objects resulted in a consistent startle reflex potentiation and behavioral avoidance in both fear groups. This activation of the basic aversive system was independent of the autonomic pattern of the fear responses, which differed for the high-fear groups. These results suggest that the probe startle response indexes the organism's basic motivational disposition and add new information to the assessment of fear.