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The major goal of the present functional magnetic resonance imaging study was to investigate the influence of disgust sensitivity on hemodynamic responses during disgust induction. Fifteen subjects viewed three different film excerpts (duration: 135 s each) with disgust-evoking, threatening and neutral content. The films were presented in a block design with four repetitions of each condition. Afterwards, subjects gave affective ratings for the films and answered the questionnaire for the assessment of disgust sensitivity (QADS, []). The subjects' overall disgust sensitivity was positively related to their experienced disgust, as well as to their prefrontal cortex activation during the disgust condition. Further, there was a positive correlation between subjects' scores on the QADS subscale spoilage/decay and their amygdala activation (r=0.76). This was reasonable since the disgust film clip depicted a cockroach-invasion and the subscale spoilage/decay contains, among others, an item asking for disgust towards cockroaches. The study stresses, in accordance to previous studies, the importance of considering personality traits when studying affective responses in fMRI studies.

Functional magnetic resonance imaging (fMRI) studies consistently demonstrate an enhanced activation of the visual cortex in reaction to emotionally salient visual stimuli. This increase of activation is probably modulated by top-down processes, that are initiated in emotion processing structures, specifically the amygdala and the orbitofrontal cortex. In the present fMRI study, a differential fear conditioning paradigm was applied to investigate this assumed modulation. Hemodynamic responses towards a neutral visual stimulus (CS+) predicting an electrical stimulation (UCS) were compared with responses towards a neutral and unpaired stimulus (CS-). Thereby, particularly the time courses of neural responses were considered. Skin conductance measures were concurrently recorded. Our results show that the differentiation between CS+ and CS- within the amygdala and the extended visual cortex was accomplished during a late acquisition phase. In the orbitofrontal cortex the differentiation occurred at an earlier stage and was then sustained throughout acquisition. It is suggested that these altering activation patterns are reflecting different phases of learning, integrating the analyzed regions to varying degrees. Additionally, the results indicate that statistical analyses comprising a temporal variation of hemodynamic responses are more likely to detect amygdala activation.

Global variations of BOLD-fMRI signal are often considered as nuisance effects. This unwanted source of variance is commonly eliminated using proportional global signal scaling (PGSS). However, application of PGSS relies on the assumption that global variations of BOLD signal and experimental conditions are uncorrelated. It has been shown for cognitive tasks that the unjustified application of PGSS might greatly distort statistical results. The present study examined this issue in the domain of emotion research. Specifically, fMRI data were obtained in a block-design, while 21 subjects passively viewed high and low emotionally arousing pleasant, unpleasant, and neutral pictures. Violations of the orthogonality assumption were found for analyses of emotional pictures high in arousal, causing dramatically different outcomes when compared to analyses performed without PGSS. Application of PGSS was associated with attenuated emotional activation in visual cortical areas, insensitivity to emotional activations in limbic and paralimbic regions, and widely distributed artificial deactivations. In contrast, the orthogonality assumption was not violated for low arousing emotional materials. Thus, the validity of using PGSS varied as a function of the emotional arousal of the stimuli. Taken together, the unwarranted use of PGSS might contribute to conflicting results in affective neuroscience fMRI studies, in particular with respect to limbic and paralimbic structures.

OBJECTIVES: The study aimed to clarify whether cognitive and psychomotor performance, which are important for occupational and traffic safety, are impaired by working permanent night shifts (NSs) compared with early-late two shifts (TSs) and whether age and chronobiological type influences the relationship between shift and performance. METHODS: The study included 44 male automobile workers, 20 working TSs and 24 working NSs. Chronobiological type was determined by questionnaire (D-MEQ). Each subject was tested at the beginning and end of the shift for alertness [by a visual analogue scale (VAS)]; feeling of well-being (Basler); concentration and accuracy (d2); reaction speed, orientation and reaction to stress (Vienna System). RESULTS: TS workers were more frequently morning types whereas the NS workers were more frequently evening types. In the performance tests, the TS and NS workers did not differ at shift start or shift end. Over the course of the shift, concentration and accuracy improved in both groups, as did reaction to stress. Chronobiological type alone or in combination with shift type had no effect on performance. CONCLUSIONS: The results of this study indicate that-if chosen voluntarily-working NSs has no immediate negative effects on cognitive and psychomotor performance when compared with working TSs. There was no indication of an increased risk of accidents after working NSs. The unequal distribution of the circadian types in the shift groups may indicate selection.

We examined whether males and females differ in the intensity and laterality of their hemodynamic responses towards visual disgust and fear stimuli. Forty-one female, and 51 male subjects viewed disgust-inducing, fear-inducing and neutral pictures in an fMRI block design. Self-report data indicated that the target emotions had been elicited successfully with women responding stronger than men. While viewing the fear pictures, which depicted attacks by humans or animals, men exhibited greater activation in the bilateral amygdala and the left fusiform gyrus than women. This response pattern may reflect greater attention from males to cues of aggression in their environment. Further, the lateralization of brain activation was comparable in the two genders during both aversive picture conditions.

Recent work has demonstrated the feasibility of simultaneous electroencephalography (EEG) and functional magnetic resonance imaging (fMRI). Virtually no systematic comparisons between EEG recorded inside and outside the MR scanner have been conducted, and it is unknown if different kinds of frequency mix, topography, and domain-specific processing are uniformly recordable within the scanner environment. The aim of the study was to investigate several typical EEG waveforms in the same subjects inside the magnet during fMRI and outside the MR examination room. We examined whether uniform artifact subtraction allows the extraction of these different EEG waveforms inside the scanner during EPI scanning to the same extent as outside the scanner. Three well-established experiments were conducted, eliciting steady state visual evoked potentials (SSVEP), lateralized readiness potentials (LRP), and frontal theta enhancement induced by mental addition. All waveforms could be extracted from the EEG recorded during fMRI. Substantially no differences in these waveforms of interest were found between gradient-switching and intermediate epochs during fMRI (only the SSVEP-experiment was designed for a comparison of gradient-with intermediate epochs), or between waveforms recorded inside the scanner during EPI scanning and outside the MR examination room (all experiments). However, non-specific amplitude differences were found between inside and outside recorded EEG at lateral electrodes, which were not in any interaction with the effects of interest. The source of these differences requires further exploration. The high concordance of activation patterns with published results demonstrates that EPI-images could be acquired during EEG recording without significant distortion.

PURPOSE: The relationship between auditory temporal-order perception and phoneme discrimination has been discussed for several years, based on findings, showing that patients with cerebral damage in the left hemisphere and aphasia, as well as children with specific language impairments, show deficits in temporal-processing and phoneme discrimination. Over the last years several temporal-order measurement procedures and training batteries have been developed. However, there exists no standard diagnostic tool for adults that could be applied to patients with aphasia. Therefore, our study aimed at identifying a feasible, reliable and efficient measurement procedure to test for auditory-temporal processing in healthy young and elderly adults, which in a further step can be applied to patients with aphasia. METHODS: The tasks varied according to adaptive procedures (staircase vs. maximum-likelihood), stimuli (tones vs. clicks) and stimulation modes (binaural- vs. alternating monaural) respectively. A phoneme-discrimination task was also employed to assess the relationship between temporal and language processing. RESULTS: The results show that auditory temporal-order thresholds are stimulus dependent, age related, and influenced by gender. Furthermore, the cited relationship between temporal-order threshold and phoneme discrimination can only be confirmed for measurements with pairs of tones. CONCLUSION: Our results indicate, that different norms have to be established for different gender and age groups. Furthermore, temporal-order measurements with tones seem to be more suitable for clinical intervention studies than measurements with clicks, as they show higher re-test reliabilities, and only for measurements with tones an association with phoneme-discrimination abilities was found.

In alexithymia a frontal dysfunction is supposed to be a neurobiological correlate. This study focuses on distorted patterns of neuronal activity evoked by emotional stimuli in alexithymics and controls. Out of hospitalised patients with psychosomatic diseases 8 patients with a high score (HA) and 8 with a low one (NA) on the TAS-20 were investigated with fMRI during emotional stimulation which included pictures evoking anxiety and disgust as well as neutral illustrations. As response to negative affect arousing visual stimulation HA in comparison to NA showed a lower activation in the right medial prefrontal cortex and in the right amygdala. The results were significant for the emotion disgust. The results support the existence of a complex central feedback circuit consisting of regions of the prefrontal cortex and limbic structures to process negative affects. Hypothetically a fundamental factor for the emergence of alexithymic traits is an inhibiting process between affect processing (e. g. medial prefrontal cortex, anterior cingulum) and affect generating structures (e. g. amygdala). Furthermore our findings confirm the hypothesis that alexithymia is a disorder of higher cerebral function.

We assessed the effect of size and localization of a brain lesion on patients' abilities to perceive the temporal order of two acoustic stimuli. In those patients who had performed with impaired order thresholds, local overlaps of lesions as analyzed with CT were found in specific left-hemispheric regions of the temporal and parietal lobe. However, a moderate association of lesion size and temporal-order threshold was found among all brain-injured patients (n = 30), a correlation that was most pronounced in patients with right-hemispheric lesions. This non-specific effect of lesion size has to be discussed critically with respect to behavioral findings of an association between temporal-processing abilities and language competence.

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.

Normally we experience the visual world as stable. Ambiguous figures provide a fascinating exception: On prolonged inspection, the "Necker cube" undergoes a sudden, unavoidable reversal of its perceived front-back orientation. What happens in the brain when spontaneously switching between these equally likely interpretations? Does neural processing differ between an endogenously perceived reversal of a physically unchanged ambiguous stimulus and an exogenously caused reversal of an unambiguous stimulus? A refined EEG paradigm to measure such endogenous events uncovered an early electrophysiological correlate of this spontaneous reversal, a negativity beginning at 160 ms. Comparing across nine electrode locations suggests that this component originates in early visual areas. An EEG component of similar shape and scalp distribution, but 50 ms earlier, was evoked by an external reversal of unambiguous figures. Perceptual disambiguation seems to be accomplished by the same structures that represent objects per se, and to occur early in the visual stream. This suggests that low-level mechanisms play a crucial role in resolving perceptual ambiguity.

Abnormal auditory temporal processing might be an underlying deficit in language disabilities. The auditory temporal-order threshold, one measure for temporal processing abilities, is defined as the shortest time interval between two acoustic events necessary for a person to be able to identify the correct temporal order. In our study, we examined the reliability of the auditory temporal-order threshold during a one-week period and over a time interval of four months in normally developing children aged 5 to 11 years. The results of our method show that children younger than 7 years have difficulties performing the task successfully. The reliability of the assessment of the temporal-order threshold during a period of one week is only moderate, and its stability over a time interval of four months is low. The results show that auditory-order thresholds in children have to be treated with caution. A high temporal-order threshold does not necessarily predict disabilities in temporal processing.

We investigated subjective and hemodynamic responses towards disgust-inducing, fear-inducing, and neutral pictures in a functional magnetic resonance imaging study. Within an interval of 1 week, 24 male subjects underwent the same block design twice in order to analyze possible response changes to the repeated picture presentation. The results showed that disgust-inducing and fear-inducing scenes provoked a similar activation pattern in comparison to neutral scenes. This included the thalamus, primary and secondary visual fields, the amygdala, the hippocampus, and various regions of the prefrontal cortex. During the retest, the affective ratings hardly changed. In contrast, most of the previously observed brain activations disappeared, with the exception of the temporo-occipital activation. An additional analysis, which compared the emotion-related activation patterns during the two presentations, showed that the responses to the fear-inducing pictures were more stable than the responses to the disgust-inducing ones.

The majority of neuroimaging studies on affective processing have indicated that there are specific brain structures, which are selectively responsive to fear and disgust. Whereas the amygdala is assumed to be fear-related, the insular cortex is most likely involved in disgust processing. Since these findings are mainly a result of studies focusing exclusively either on fear, or on disgust, but rarely on both emotions together, the present experiment explored the neural effects of viewing disgusting and fear-inducing pictures in contrast to neutral pictures. This was done by means of functional magnetic resonance imaging (fMRI) with 19 subjects (nine males, ten females), who also gave affective ratings for the presented pictures. The fear and the disgust pictures were able to induce the target emotions and they received comparable valence and arousal ratings. The processing of both aversive picture types was associated with an increased brain activation in the occipital-temporal lobe, in the prefrontal cortex, and in the thalamus. The amygdala was significantly activated by disgusting, but not by fear-inducing, pictures. Thus, our data are in contrast with the idea of highly emotion-specific brain structures and rather suggest the existence of a common affective circuit.

Findings from animal as well as human neuroimaging studies suggest that reward delivery is associated with the activation of subcortical limbic and prefrontal brain regions, including the thalamus, the striatum, the anterior cingulate and the prefrontal cortex. The aim of the present study was to explore if these reward-sensitive regions are also activated during the anticipation of reinforcers that vary with regard to their motivational value. A differential conditioning paradigm was performed, with the presentation of a rewarded reaction time task serving as the unconditioned stimulus (US). Depending on their reaction time, subjects were given (or not given) a monetary reward, or were presented with a verbal feedback consisting of being fast or slow. In a third control condition no task needed to be executed. Each of the three conditions was introduced by a different visual cue (CS). Brain activation of 27 subjects was recorded using event-related functional magnetic resonance imaging. The results showed significant activation of the substantia nigra, thalamic, striatal, and orbitofrontal brain regions as well as of the insula and the anterior cingulate during the presentation of a CS signalling a rewarded task. The anticipation of a monetary reward produced stronger activation in these regions than the anticipation of positive verbal feedback. The results are interpreted as reflecting the motivation-dependent reactivity of the brain reward system with highly motivating stimuli (monetary reward) leading to a stronger activation than those less motivating ones (verbal reward).

On duration judgments lasting seconds to minutes, which are thought to be cognitively mediated, women typically perceive time intervals as longer than men do. On a perceptual level in the milliseconds range, few reports indicate higher acuity of temporal processing in men than in women. In this study, sex differences in the perception of temporal order of two acoustic stimuli were identified in neurologically healthy subjects, as well as in brain-injured patients with lesions in either the left or the right hemisphere. Women needed longer interstimulus intervals than men before they were able to indicate the correct temporal order of two clicks. Neurobiological evidence and findings on cognitive strategies are discussed to explain the apparent psychophysical sex differences.

The cerebellum and the hippocampus are key structures for the acquisition of conditioned eyeblink responses. Whereas the cerebellum seems to be crucial for all types of eyeblink conditioning, the hippocampus appears to be involved only in complex types of learning. We conducted a differential conditioning study to explore the suitability of the design for magnetencephalography (MEG). In addition, we compared cerebellar and hippocampal activation during differential delay and trace conditioning. Comparable conditioning effects were seen in both conditions, but a greater resistance to extinction for trace conditioning. Brain activation differed between paradigms: delay conditioning provoked activation only in the cerebellum and trace conditioning only in the hippocampus. The results reflect differential brain activation patterns during the two types of eyeblink conditioning.

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.