Wilfried Scharmüller

Appetite regulation during food cue exposure: a comparison of normal-weight and obese women.

Obese individuals react to cues of high caloric food with enhanced craving and brain reward system activation. In the present study, we analyzed neural correlates of craving regulation and expected a regulatory deficit in obesity. We conducted an event-related functional magnetic resonance imaging study, where 12 obese women and 14 normal-weight women were exposed to pictures depicting high-caloric food and non-food items. The participants were instructed to either passively look at the pictures, or to regulate (increase, decrease) their appetite. During the passive viewing of food cues, the obese participants showed greater insula activation than the lean participants. Moreover, the obese group displayed stronger dorsolateral prefrontal cortex involvement when attempting to attenuate food-elicited craving. Our data point to an enhanced food cue reactivity and a more effortful strategy for appetite control in obese individuals.

Source localization of late electrocortical positivity during symptom provocation in spider phobia: an sLORETA study.

This symptom provocation study on spider phobia investigated sources of late event-related potentials (ERPs) using sLORETA (standardized low resolution brain electromagnetic tomography). Twenty-five phobic female patients and 20 non-phobic controls were confronted with phobia-relevant, generally fear-inducing, disgust-inducing and affectively neutral pictures while an electroencephalogram was recorded. Mean amplitudes of ERPs were extracted in the time windows 340–500 ms (P300) and 550–770 ms (late positive potential, LPP). Phobics showed enhanced P300 and LPP amplitudes in response to spider pictures relative to controls. Sources were mainly located in areas engaged in visuo-attentional processing (occipital and parietal regions, ventral visual pathway). Moreover, there were sources in areas which are crucial for emotional processing and the representations of aversive bodily states (cingulate cortex, insula). Further sources were located in premotor areas reflecting the priming of flight behaviour. Our findings are in good accordance with existing brain imaging studies and underline that source localization is a useful alternative for identifying phobia-relevant cortical regions.

Psychophysiology of spider phobia in 8- to 12-year-old girls

The present investigation focused on late event-related potentials (ERPs) and facial electromyographic (EMG) activity in response to symptom provocation in 8- to 12-year-old spider phobic girls and compared results to those in non-fearful controls. Fourteen patients and 14 controls were presented with phobia-relevant, generally fear-inducing, disgust-inducing and affectively neutral pictures in an EEG/EMG session. ERPs were extracted in the time-windows 340-500ms (P300) and 550-770ms (late positive potential, LPP). Relative to controls, phobics showed enhanced amplitudes of P300 and LPP in response to spider pictures. This result is interpreted to reflect motivated attention to emotionally salient stimuli. Moreover, phobics showed enhanced average facial EMG activity of the levator labii and the corrugator supercilii in response to spider pictures, reflecting the negative valence and disgust relevance of spiders. Additionally, spider phobic girls relative to controls showed higher overall disgust proneness and heightened average facial EMG activity in both muscle regions in response to disgust stimuli, possibly revealing a disgust-based origin of spider phobia in children. These aspects should be considered in psychotherapeutic treatment of childhood spider phobia.

Sex differences in the functional and structural neuroanatomy of dental phobia

Although dental phobia is a common mental disorder, which afflicts both men and women, little is known about sex differences at the neural level. Patients suffering from dental phobia (20 men, 25 women) and healthy controls (18 men, 23 women) participated in a functional magnetic resonance imaging (fMRI) experiment. They were shown pictures depicting dental treatment, generally fear-eliciting, disgust-eliciting and neutral contents. After the fMRI experiment, the participants rated the affective value of the pictures. Additionally, grey matter volume (GMV) was compared between patients and controls, as well as between the sexes. Male and female patients responded differently to the phobogenic pictures. Women showed greater activation of the caudate nucleus, whereas men exhibited enhanced dorsolateral prefrontal cortex (DLPFC) involvement. Their DLPFC activation was negatively correlated with experienced arousal. Dentophobic females were characterized by a greater caudate volume relative to phobic males. The GMV of this structure was positively correlated with experienced arousal during exposure and symptom severity, only in female patients. This study provides first evidence of sex-specific brain activation and structure in patients suffering from dental phobia. The neural pattern during symptom provocation as well as the brain structural specificity might mirror different attention and self-control strategies of both sexes. The consideration of such differences could contribute to greater effectiveness in treating dental phobia.

Disgust regulation via placebo: an fMRI study

The present fMRI study investigated whether placebo treatment can change disgust feelings. Disgust-prone women underwent a retest design where they were presented with disgusting, fear-eliciting and neutral pictures once with and once without a placebo (inert pill presented with the suggestion that it can reduce disgust symptoms). The placebo provoked a strong decrease of experienced disgust, which was accompanied by reduced insula activation. Exploratory psychophysiological interaction analyses revealed decreased connectivity in a network consisting of the insula, the amygdala, the anterior cingulate cortex and the orbitofrontal cortex. Moreover, the placebo increased amygdala-DMPFC coactivation. Our findings suggest that placebo use can modulate a specific affective state and might be an option as a first therapy step for clinical samples characterized by excessive and difficult-to-control disgust feelings.

Cerebellar activity and connectivity during the experience of disgust and happiness

Previous research indicates that distinct subregions of the cerebellum are involved in the processing of different primary emotions. How this is achieved in terms of connectional specificity with other brain areas still needs to be elucidated. We employed functional magnetic resonance imaging in order to investigate cerebellar activation and connectivity relevant for the processing of two basic emotions. Thirty-four healthy women were presented with pictures that specifically elicited happiness and disgust with the instruction to rate the intensity of the experienced feelings. The contrasting of both affective conditions showed that disgust evoked activation of the vermis and the cerebellar hemispheres, whereas happiness-associated activation was restricted to the posterior cerebellum. Both emotions provoked increased connectivity of the cerebellum with limbic regions. The observed extended connectivity patterns can explain why cerebellar lesions are able to produce pronounced changes of affective experience in the afflicted patients.

Affective perception and imagery: A NIRS study.

The activation of cortical attention networks during affective picture processing has been extensively studied, whereas little is known about affective imagery. It is still unclear whether differences in emotional stimulus content are able to modulate visual cortex activation during imagery. Moreover, individual differences in emotional reactivity and imagery ability have not been investigated. The aim of this experiment was to examine these processes by means of near-infrared spectroscopy (NIRS). Thirty-five healthy adults were instructed to look at affective (disgust and happy) and neutral pictures and afterwards visualize them during multi-channel NIRS recording. Our main results indicated a differential involvement of parietal and occipital areas in the perception and imagery of affective pictures. In general, picture perception provoked increased oxygenated hemoglobin in occipital regions, whereas imagery was associated with an increase in parietal areas. Emotional content modulated activation of the left occipital cortex during both picture perception and imagery. Affective pictures (disgust and happy) provoked greater activation compared to neutral ones. Additionally, the self-rated imagery ability of the participants was positively correlated with their occipital activation during affective imagery. Thus, occipital activation might be crucial for the quality of imagery. In contrast, all correlations with emotional traits (e.g. trait disgust) and oxygenation were nonsignificant, which might be due to the fact that those personality factors predominantly modulate the activation of subcortical limbic structures which are not accessible with NIRS.

Placebo treatment can alter primary visual cortex activity and connectivity.

Placebo treatment can alter brain activation in regions implicated in affective processing and cognitive control of emotions. This functional magnetic resonance imaging (fMRI) study investigated whether a placebo can additionally modulate visual cortex activity and connectivity during affective picture perception. The participants underwent a retest design where they were presented with disgusting, fear-eliciting and neutral pictures both with, and without a placebo (inert pill presented with the suggestion that it can reduce disgust symptoms). The placebo provoked a strong decrease in experienced disgust. This was accompanied by a reduced activation of the primary visual cortex, which showed reduced interaction with the amygdala and the insula. Accordingly, placebos are able to affect basic perceptive processes.

Individual differences in cognitive reappraisal usage modulate the time course of brain activation during symptom provocation in specific phobia

BackgroundExtinction learning is proposed to be one key mechanism of action underlying exposure-based cognitive-behavioral therapy (CBT) in specific phobia. Beyond that, cognitive reappraisal, one important strategy to regulate negative emotions, is a crucial component of CBT interventions, but has been disregarded in previous studies investigating neural change processes in specific phobia. The aim of this study was to investigate the association of individual differences in habitual/dispositional cognitive reappraisal usage and the time course of brain activation during phobic stimulation in specific phobia.MethodsDental phobic patients and healthy control subjects participated in a functional magnetic resonance imaging (fMRI) study whilst being confronted with phobic, disgust, fear and neutral pictures. Individual differences in cognitive reappraisal usage were assessed via a self-report questionnaire and correlated with activation decreases over the course of time.ResultsPhobic individuals with higher dispositional cognitive reappraisal scores showed a more pronounced activation decline in the right dorsomedial prefrontal cortex (dmPFC) which might be associated with a diminution of explicit cognitive emotion regulation over the course of time. Less decrease of activation in the right ventromedial prefrontal cortex (vmPFC) and the lateral orbitofrontal cortex (lOFC) over time in subjects with higher cognitive reappraisal scores might be related to a stronger automatic regulation of emotions or even emotional relearning. Additionally, phobic subjects compared with healthy controls showed a stronger habituation of the left dmPFC over the course of symptom provocation.ConclusionsThe results of this study show for the first time that individual differences in cognitive reappraisal usage are associated with the time course of brain activation during symptom provocation in specific phobia. Additionally, the present study gives first indications for the importance of considering individual differences in cognitive reappraisal usage in the treatment of specific phobia.

Altered cerebellar-amygdala connectivity in violent offenders: A resting-state fMRI study.

It has repeatedly been reported, that there are differences in grey matter volume (GMV) between violent offenders and non-violent controls. However, it remains unclear, if structural brain abnormalities influence resting-state functional connectivity (RS-fc) between brain regions. Therefore, in the present investigation, 31 male high-risk violent prisoners were compared to 30 non-criminal controls with respect to RS-fc between brain areas. Seed regions for resting-state analysis were selected based on GMV differences between the two groups. Overall, inmates had more GMV in the cerebellum than controls and revealed higher RS-fc between the cerebellum and the amygdala. In contrast, controls relative to prisoners showed higher RS-fc between the cerebellum and the orbitofrontal cortex (OFC). In addition, controls showed more GMV in the dorsolateral prefrontal cortex (DLPFC). Inmates relative to controls had higher RS-fc within the DLPFC. Results are discussed with respect to cerebellar contributions to a brain network underlying moral behavior and violence. Enhanced cerebellar-amygdala connectivity in violent offenders might reflect alterations in the processing of moral emotions. Heightened functional connectivity between cerebellar hemispheres and the OFC in controls could be a correlate of enhanced emotion regulation capacities. Higher functional intra-DLPFC connectivity in violent offenders might represent an effort to regulate emotions.