Boris Suchan

Structural encoding and recognition of biological motion: evidence from event-related potentials and source analysis.

In the present study, we investigated how different processing stages involved in the perceptual analysis of biological motion (BM) are reflected by modulations in event-related potentials (ERP) in order to elucidate the time course and location of neural processing of BM. Data analysis was carried out using conventional averaging techniques as well as source localization with low resolution brain electromagnetic tomography (LORETA). ERPs were recorded in response to point-light displays of a walking person, an inverted walking person and displays of scrambled motion. Analysis yielded a pronounced negativity with a peak at 180 ms after stimulus onset which was more pronounced for upright walkers than for inverted walkers and scrambled motion. A later negative component between 230 and 360 ms after stimulus onset had a larger amplitude for upright and inverted walkers as compared to scrambled walkers. In the later component, negativity was more pronounced in the right hemisphere revealing asymmetries in BM perception. LORETA analysis yielded evidence for sources specific to BM within the right fusiform gyrus and the right superior temporal gyrus for the second component, whereas sources for BM in the early component were located in areas associated with attentional aspects of visual processing. The early component might reflect the pop-out effect of a moving dot pattern representing the highly familiar form of a human figure, whereas the later component might be associated with the specific analysis of motion patterns providing biologically relevant information.

Reduction of gray matter density in the extrastriate body area in women with anorexia nervosa

Body processing has been associated functionally to the so called extrastriate body area (EBA) which is located in the lateral occipital cortex. As body image disturbance is one of the main diagnostic criteria in anorexia nervosa (AN) this study aimed at looking for alterations in gray matter density in women with (AN) especially in the EBA. High resolution T1 images from 15 women with AN and 15 age matched healthy controls women were contrasted using voxel based morphometry (VBM). Additionally functional localizer scans were used to determine functionally the EBA of each participant. In general, total gray matter volumes did differ between groups. VBM results yielded evidence for a reduction of gray matter density in the left EBA. This reduction, which resulted from whole brain analysis, was localised within the activation cluster of the EBA localizer scan. The current results provide for the first time evidence for structural alterations in the EBA in patients with AN which might suggest that body image distortion is related at least in part to structural alteration in the EBA.

Losing your head: Behavioral and electrophysiological effects of body inversion

The present study aimed to further explore the mechanisms underlying the perception of human body shapes. Behavioral and electrophysiological inversion effects were studied for human bodies with and without heads and for animal bodies (cats, dogs, and birds). Recognition of human bodies (with heads) was adversely affected by stimulus inversion, and the N170 had longer latencies and higher amplitudes for inverted compared to upright human bodies. Human body shapes presented without heads yielded the opposite result pattern. The data for animal bodies did not yield consistent effects. Taken together, the present findings suggest that human bodies might be processed by specialized cortical mechanisms which are at least partly dissociable from mechanisms involved in object or face processing.

Foreseeing the future: Occurrence probability of imagined future events modulates hippocampal activation

Episodic memory and episodic future thinking are known to share a set of brain regions. Potential differences in activation patterns associated with the two conditions are as yet inconclusive, in particular with respect to hippocampal involvement. Hippocampal activation is modulated by a range of phenomenal qualities during the imagination of both past and future events (Addis et al. ( 2004 ) Hippocampus 14:752–762; Addis and Schacter ( 2008 ) Hippocampus 18:227–237). A relevant variable in this regard is the occurrence probability of an episode, which varies for future but not past events and thus cannot be equated across conditions. Using parametric modulation analysis, we investigated the effect of occurrence probability of imagined future events on brain activation patterns, while effects of temporal distance, amount of details, and emotionality were controlled for. Activation of right anterior hippocampus increased with decreasing occurrence probability, presumably reflecting higher processing demands during binding of more disparate details for unlikely events. This finding may contribute to the understanding of previously reported inconsistent results concerning hippocampal involvement during the imagination of past and future events.

Empathy and social problem solving in alcohol dependence, mood disorders and selected personality disorders

Altered empathic responding in social interactions in concert with a reduced capacity to come up with effective solutions for interpersonal problems have been discussed as relevant factors contributing to the development and maintenance of psychiatric disorders. The aim of the current work was to review and evaluate 30 years of empirical evidence of impaired empathy and social problem solving skills in alcohol dependence, mood disorders and selected personality disorders (borderline, narcissistic, antisocial personality disorders/psychopathy), which have until now received considerably less attention than schizophrenia or autism in this realm. Overall, there is tentative evidence for dissociations of cognitive (e.g. borderline personality disorder) vs. emotional (e.g. depression, narcissism, psychopathy) empathy dysfunction in some of these disorders. However, inconsistencies in the definition of relevant concepts and their measurement, scarce neuroimaging data and rare consideration of comorbidities limit the interpretation of findings. Similarly, although impaired social problem solving appears to accompany all of these disorders, the concept has not been well integrated with empathy or other cognitive dysfunctions as yet.

When the future becomes the past: Differences in brain activation patterns for episodic memory and episodic future thinking

Episodic memory and episodic future thinking activate a network of overlapping brain regions, but little is known about the mechanism with which the brain separates the two processes. It was recently suggested that differential activity for memory and future thinking may be linked to differences in the phenomenal properties (e.g., richness of detail). Using functional magnetic resonance imaging in healthy subjects and a novel experimental design, we investigated the networks involved in the imagery of future and the recall of past events for the same target occasion, i.e. the Christmas and New Years holidays, thereby keeping temporal distance and content similar across conditions. Although ratings of phenomenal characteristics were comparable for future thoughts and memories, differential activation patterns emerged. The right posterior hippocampus exhibited stronger memory-related activity during early event recall, and stronger future thought-related activity during late event imagination. Other regions, e.g., the precuneus and lateral prefrontal cortex, showed the reverse activation pattern with early future-associated and late past-associated activation. Memories compared to future thoughts were further related to stronger activation in several visual processing regions, which accords with a reactivation of the original perceptual experience. In conclusion, the results showed for the first time unique neural signatures for both memory and future thinking even in the absence of differences in phenomenal properties and suggested different time courses of brain activation for episodic memory and future thinking.

Dissociation of grey and white matter reduction in spinocerebellar ataxia type 3 and 6: A voxel-based morphometry study

The aim of this study was to examine the different patterns of cerebellar and/or brainstem atrophy in spinocerebellar ataxia (SCA) type 3 and 6. Eighteen patients (SCA3 n=9, SCA6 n=9) and 15 healthy volunteers were studied. Voxel-based morphometry (VBM) was applied to segmented grey matter (GM) and white matter (WM) of high-resolution T1-weighted brain volumes of each group. We found reduction of grey matter in the pons as well as in the vermis in SCA3 as compared to control subjects. In SCA6 significant grey matter loss was found in hemispheric lobules bilaterally as well as in the vermis. White matter analysis revealed significant changes in SCA3, especially in the pons, in the white matter surrounding the dentate nucleus (DN) and in the cerebellar peduncles, whereas no significant white matter reduction was found in SCA6 patients. Our results demonstrate different patterns of grey and white matter affection detected by magnetic resonance imaging (MRI) in SCA3 and SCA6 patients, confirming the pathological concept of cortical cerebellar atrophy in SCA6. In contrast, SCA3 represents a form of ponto-cerebellar atrophy with predominant affection of pontine nuclei and fibre tracts.

A bilateral occipitotemporal network mediates face perception.

The aim of the present study was to further explore the neuronal mechanisms of face processing in healthy subjects which may help to understand the difficulties experienced by prosopagnosia subjects. A further goal was to compare face specific activation patterns in the right and left occipital face area (OFA) and fusiform face area (FFA) for famous faces, non-famous faces and caricatures of famous faces in four individuals suffering from developmental prosopagnosia (DP) and seven healthy controls, using functional magnetic resonance imaging and psychophysiological interaction analysis (PPI). Control subjects showed higher face related activations in the right compared to the left FFA. Caricatures of faces of famous people and photographs of non-famous faces yielded higher percent signal changes in the OFA and FFA compared to photographs of famous faces. These data support the idea that the OFA and FFA discriminate between familiar and new face representations. The activation patterns of DP subjects were heterogeneous, with none of the patients showing bilateral face related activations in both OFA and FFA. There was no evidence of a left hemispheric activation when the right homologue failed to be activated, supporting the view of a right hemispheric dominance in face perception. PPI analysis indicated a link between activation of the right FFA and the other three tested regions, the left FFA and the right and left OFA. In summary, all four face related brain regions appear to be necessary for successful face processing, and disruption of one component may lead to face recognition deficits.

Event‐related potentials reflect heterogeneity of developmental prosopagnosia

Event‐related potential (ERP) studies of developmental prosopagnosia (DP) are rare. Previous ERP investigations have reported smaller N170 amplitude differences between faces and objects in at least three prosopagnosics. The present study is based on a combination of behavioural and electrophysiological assessment of face processing. The aim was to investigate the face‐specifity of the N170 in both healthy subjects and a group of DP individuals (Nu2003=u20034), using famous and nonfamous faces, caricatures and houses as stimuli. All prosopagnosic subjects showed impairments in recognition of famous faces, memory for faces and learning new faces in behavioural assessment. In healthy subjects the largest effects were found at parieto‐occipital electrode positions (PO7 and PO8), along with a familiarity effect at these electrode positions. Thus, parieto‐occipital areas appear to play an important role in face processing. Three prosopagnosics showed reliable N170 amplitude differences between faces and nonface stimuli, whereas one DP individual showed significantly reduced amplitude differences between faces and nonface objects. The behavioural and electrophysiological data support the idea that DP reflects a heterogeneous impairment and that face processing deficits are not necessarily correlated with a lack of face‐specific N170.

Changes in neuronal correlates of body image processing by means of cognitive-behavioural body image therapy for eating disorders: a randomized controlled fMRI study

BACKGROUNDnPrevious neuroimaging studies have demonstrated abnormalities in visual body image processing in anorexia and bulimia nervosa, possibly underlying body image disturbance in these disorders. Although cognitive behavioural interventions have been shown to be successful in improving body image disturbance in eating disorders, no randomized controlled study has yet analysed treatment-induced changes in neuronal correlates of visual body image processing.nnnMETHODnAltogether, 32 females with eating disorders were randomly assigned either to a manualized cognitive behavioural body image therapy consisting of 10 group sessions, or to a waiting list control condition. Using functional magnetic resonance imaging, brain responses to viewing photographs of ones own and another females body taken from 16 standardized perspectives while participants were wearing a uniform bikini were acquired before and after the intervention and the waiting time, respectively.nnnRESULTSnData indicate a general blood oxygen level dependent signal enhancement in response to looking at photographs of ones own body from pre- to post-treatment, whereas exclusively in the control group activation decreases from pre- to post-waiting time were observed. Focused activation increases from pre- to post-treatment were found in the left middle temporal gyrus covering the coordinates of the extrastriate body area and in bilateral frontal structures including the middle frontal gyrus.nnnCONCLUSIONSnResults point to a more intense neuronal processing of ones own body after the cognitive behavioural body image therapy in cortical regions that are responsible for the visual processing of the human body and for self-awareness.