Ihre Suche

Priming tasks are used for investigating the deficits of selective attention in schizophrenia, which are thought to be related to the psychotic symptoms. Priming was assessed in acutely psychotic unmedicated (n = 22) and medicated (n = 36) schizophrenia patients and in control subjects (n = 42). The subjects had to indicate the location of a target stimulus in two consecutive stimulus displays (prime and probe). Each stimulus appeared together with a distractor on a screen. Negative Priming is characterized by an increase in reaction time, whenever a probe target is presented at a prime distractor location. Positive Priming is characterized by a decrease in reaction time, when the probe target is presented at the prime target location. Schizophrenia patients altogether showed no abnormalities in priming effects, neither in the acute phase of illness (medicated and unmedicated) nor in partial remission (one month later, medicated). In unmedicated patients however Negative Priming was inversely correlated with the severity of positive symptoms. This indicates a priming deficit in a small subgroup of severely ill patients. The data support the notion that automatic (implicit) mechanisms of learning are unimpaired in schizophrenia patients unless symptoms exceed a certain critical level.

Cognitive deficits affecting memory, attention and speed of information processing are common in multiple sclerosis (MS). The mechanisms of cognitive impairment remain unclear. Here, we examined the association between neuropsychological test performance and brain atrophy in a group of mildly disabled patients with relapsing-remitting MS. We applied voxel-based morphometry (SPM2) to investigate the distribution of brain atrophy in relation to cognitive performance. Patients had lower scores than control subjects on tests of memory and executive function, including the PASAT, Digit Span Backward and a test of short-term verbal memory (Memo). Among patients, but not healthy controls, performance on the PASAT, a comprehensive measure of cognitive function and reference task for the cognitive evaluation of MS-patients, correlated with global grey matter volume as well as with grey matter volume in regions associated with working memory and executive function, including bilateral prefrontal cortex, precentral gyrus and superior parietal cortex as well as right cerebellum. Compared to healthy subjects, patients showed a volume reduction in left temporal and prefrontal cortex, recently identified as areas predominantly affected by diffuse brain atrophy in MS. A comparison of low performers in the patient group with their matched control subjects showed more extensive and bilateral temporal and frontal volume reductions as well as bilateral parietal volume loss, compatible with the progression of atrophy found in more advanced MS-patients. These findings indicate that MS-related deficits in cognition are closely associated with cortical atrophy.

Findings from several functional magnetic resonance imaging (fMRI) studies implicate the existence of a distinct neural disgust substrate, whereas others support the idea of distributed and integrative brain systems involved in emotional processing. In the present fMRI experiment 12 healthy females viewed pictures from four emotion categories. Two categories were disgust-relevant and depicted contamination or mutilation. The other scenes showed attacks (fear) or were affectively neutral. The two types of disgust elicitors received comparable ratings for disgust, fear and arousal. Both were associated with activation of the occipitotemporal cortex, the amygdala, and the orbitofrontal cortex; insula activity was nonsignificant in the two disgust conditions. Mutilation scenes induced greater inferior parietal activity than contamination scenes, which might mirror their greater capacity to capture attention. Our results are in disagreement with the idea of selective disgust processing at the insula. They point to a network of brain regions involved in the decoding of stimulus salience and the regulation of attention.

Humans show large differences in the preferred timing of their sleep and activity. This so-called "chronotype" is largely regulated by the circadian clock. Both genetic variations in clock genes and environmental influences contribute to the distribution of chronotypes in a given population, ranging from extreme early types to extreme late types with the majority falling between these extremes. Social (e.g., school and work) schedules interfere considerably with individual sleep preferences in the majority of the population. Late chronotypes show the largest differences in sleep timing between work and free days leading to a considerable sleep debt on work days, for which they compensate on free days. The discrepancy between work and free days, between social and biological time, can be described as 'social jetlag.' Here, we explore how sleep quality and psychological wellbeing are associated with individual chronotype and/or social jetlag. A total of 501 volunteers filled out the Munich ChronoType Questionnaire (MCTQ) as well as additional questionnaires on: (i) sleep quality (SF-A), (ii) current psychological wellbeing (Basler Befindlichkeitsbogen), (iii) retrospective psychological wellbeing over the past week (POMS), and (iv) consumption of stimulants (e.g., caffeine, nicotine, and alcohol). Associations of chronotype, wellbeing, and stimulant consumption are strongest in teenagers and young adults up to age 25 yrs. The most striking correlation exists between chronotype and smoking, which is significantly higher in late chronotypes of all ages (except for those in retirement). We show these correlations are most probably a consequence of social jetlag, i.e., the discrepancies between social and biological timing rather than a simple association to different chronotypes. Our results strongly suggest that work (and school) schedules should be adapted to chronotype whenever possible.

The present functional magnetic resonance imaging study investigated the fear and disgust reactivity of patients suffering from spider phobia. Ten phobics and 13 control subjects were scanned while viewing alternating blocks of phobia-relevant, generally fear-inducing, disgust-inducing and affectively neutral pictures. The patient group rated the spider pictures as being more disgust and fear evoking than the control group, and showed greater activation of the visual association cortex, the amygdalae, the right dorsolateral prefrontal cortex and the right hippocampus. Specific phobia-related activation occurred in the supplementary motor area. The patients also showed greater amygdala activation during the presentation of generally disgust- and fear-inducing pictures. This points to an elevated sensitivity to repulsive and threatening stimuli in spider phobics and implicates the amygdala as a crucial neural substrate.

The aim of this fMRI study was to explore brain structures that are involved in the processing of erotic and disgust-inducing pictures. The stimuli were chosen to trigger approach and withdrawal tendencies, respectively. By adding sadomasochistic (SM) scenes to the design and examining 12 subjects with and 12 subjects without sadomasochistic preferences, we introduced a picture category that induced erotic pleasure in one sample and disgust in the other sample. Since we also presented neutral pictures, all subjects viewed pictures of four different categories: neutral, disgust-inducing, erotic, and SM erotic pictures. The analysis indicated that several brain structures are commonly involved in the processing of disgust-inducing and erotic pictures (occipital cortex, hippocampus, thalamus, and the amygdala). The ventral striatum was specifically activated when subjects saw highly sexually arousing pictures. This indicates the involvement of the human reward system during the processing of visual erotica.

Absorption represents a disposition to experience altered states of consciousness characterized by intensively focused attention. It is correlated with hypnotic susceptibility and includes phenomena ranging from vivid perceptions and imaginations to mystical experiences. Based on the assumption that drug-induced and naturally occurring mystical experiences share common neural mechanisms, we hypothesized that Absorption is influenced by the T102C polymorphism affecting the 5-HT2a receptor, which is known to be an important target site of hallucinogens like LSD. Based on the pivotal role ascribed to the prefrontal executive control network for absorbed attention and positive symptoms in schizophrenia, it was further hypothesized that Absorption is associated with the VAL158MET polymorphism of the catechol-O-methyltransferase (COMT) gene affecting the dopaminergic neurotransmitter system. The Tellegen Absorption Scale was administered to 336 subjects (95 male, 241 female). Statistical analysis revealed that the group with the T/T genotype of the T102C polymorphism, implying a stronger binding potential of the 5-HT2a receptor, indeed had significantly higher Absorption scores (F = 10.00, P = 0.002), while no main effect was found for the COMT polymorphism. However, the interaction between T102C and COMT genotypes yielded significance (F = 3.89; P = 0.049), underlining the known functional interaction between the 5-HT and the dopaminergic system. These findings point to biological foundations of the personality trait of Absorption.

The question to what extent emotion-related brain activation depends upon the presentation design (block design vs. event-related design) and the stimulus type (scene pictures vs. pictures with facial mimic) has hardly been addressed in previous functional magnetic resonance imaging (fMRI) research. In the present fMRI experiment, 40 right-handed subjects viewed pictures with fear-inducing and disgust-inducing content as well as facial expressions of fear and disgust. Pictures of neutral objects and neutral facial mimic were used as control stimuli. The pictures were presented in a block design for half of the subjects; the other half viewed the same stimuli as singular events in randomized sequence. The participants had been instructed to passively view the pictures. Disgust-evoking scenes provoked activation in the amygdala, the insula and the orbitofrontal cortex (OFC). This applied to the blocked as well as to the event-related design. Fear-relevant scenes were associated with activity in the insula, the OFC and the middle temporal gyri in the event-related design. The presentation in a block design only led to activation in the middle temporal gyri. Facial expressions of disgust and fear did not trigger significant activation neither in the blocked nor event-related design. This surprising outcome may be a result of context and task effects. The face stimuli which were presented together with the more complex scenes in a passive viewing paradigm possibly were not salient enough to trigger emotional processing.

This functional magnetic resonance imaging study investigated the disgust- and fear-reactivity of patients suffering from obsessive-compulsive disorder (OCD). Ten OCD patients were scanned while viewing blocks of pictures showing OCD triggers from their personal environment and OCD-irrelevant disgust-inducing, fear-inducing and neutral scenes. Afterwards, the patients rated the intensity of the induced disgust, fear and OCD symptoms. The responses were compared with those of 10 healthy control subjects. The disorder-relevant pictures provoked intense OCD symptoms in the clinical group associated with increased activation in the bilateral prefrontal cortex, the left insula, the right supramarginal gyrus, the left caudate nucleus and the right thalamus. The patients gave higher disgust and fear ratings than the controls for all aversive picture categories. Neural responses towards the disorder-irrelevant disgusting and fear-inducing material included more pronounced insula activation in patients than controls. Summarizing, photos of individual OCD-triggers are an effective means of symptom provocation and activation of the fronto-striato-thalamo-parietal network. The increased insular reactivity of OCD patients during all aversive picture conditions might mirror their susceptibility to experience negative somatic states.

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.

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.

We examined the influence of disgust sensitivity and trait anxiety on disgust processing via functional magnetic resonance imaging. Data of 63 healthy females were combined across four studies, where the same disgusting and affectively neutral pictures had been presented. The disgust pictures, rated as highly repulsive, provoked activation in the occipital cortex, the left prefrontal cortex and both amygdalae. Disgust sensitivity and trait anxiety were positively, and independently from each other, correlated with the activation of the right amygdala. This points to the role of the amygdala as an integrative brain structure, whose activation can be modulated by different affective styles.

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.