Role of the human retrosplenial cortex/parieto-occipital sulcus in perspective priming.

The ability to imagine the world from a different viewpoint is a fundamental competence for spatial reorientation and for imagining what another individual sees in the environment. Here, we investigated the neural bases of such an ability using functional magnetic resonance imaging. Healthy participants detected target displacements across consecutive views of a familiar virtual room, either from the perspective of an avatar (primed condition) or in the absence of such a prime (unprimed condition). In the primed condition, the perspective at test always corresponded to the avatar's perspective, while in the unprimed condition it was randomly chosen as 0, 45 or 135deg of viewpoint rotation. We observed a behavioral advantage in performing a perspective transformation during the primed condition as compared to an equivalent amount of unprimed perspective change. Although many cortical regions (dorsal parietal, parieto-temporo-occipital junction, precuneus and retrosplenial cortex/parieto-occipital sulcus or RSC/POS) were involved in encoding and retrieving target location from different perspectives and were modulated by the amount of viewpoint rotation, the RSC/POS was the only area showing decreased activity in the primed as compared to the unprimed condition, suggesting that this region anticipates the upcoming perspective change. The retrosplenial cortex/parieto-occipital sulcus appears to play a special role in the allocentric coding of heading directions.

Visuospatial transformations and personality: evidence of a relationship between visuospatial perspective taking and self-reported emotional empathy.

In the visuospatial domain, perspective taking is the ability to imagine how a visual scene appears from an external observer's viewpoint, and can be studied by asking subjects to encode object locations in a visual scene where another individual is present and then detecting their displacement when seeing the scene from the other's viewpoint. In the current study, we explored the relationship between visuospatial perspective taking and self-report measures of the cognitive and emotional components of empathy in young adults. To this aim, we employed a priming paradigm, in which the presence of an avatar allowed to anticipate the next perceived perspective on the visual scene. We found that the emotional dimension of empathy was positively correlated with the behavioral advantage provided by the presence of the avatar, relative to unprimed perspective changes. These data suggest a link between the tendency to vicariously experience the others' emotions and the ability to perform self-other spatial transformations.

Selective role of lingual/parahippocampal gyrus and retrosplenial complex in spatial memory across viewpoint changes relative to the environmental reference frame.

Remembering object locations across different views is a fundamental competence for keeping oriented in large-scale space. Here we investigated such ability by comparing encoding and retrieval of locations across viewpoint changes relative to different spatial frames of reference. We acquired functional magnetic resonance images while subjects detected target displacements across consecutive views of a familiar virtual room, reporting changes in the target absolute position in the room (stable environmental frame), changes in its position relative to a set of movable objects (unstable object-based frame), and changes relative to their point of view (control viewer-centered frame). Behavioral costs were higher for the stable environmental frame, and a cortical network including the lingual/parahippocampal gyrus (LPHG) and the retrosplenial complex (RSC) selectively encoded spatial locations relative to this frame. Several regions, including the dorsal fronto-parietal cortex and the LPHG, were modulated by the amount of experienced viewpoint change, but only the RSC was selectively modulated by the amount of viewpoint change relative to the environmental frame, thus showing a special role in coding one's own position and heading in familiar environments.

Imagining being somewhere else: neural basis of changing perspective in space.

The capacity to imagine being somewhere else and seeing the environment from a different point of view is crucial for spatial planning in daily life and for understanding the intentions, actions, and state of mind of other people. The neural bases of spatial updating of multiple object locations were investigated using functional magnetic resonance imaging. Healthy volunteers saw an array of objects on a table in a virtual reality environment and imagined movement of their own viewpoint or rotation of the array. Their memory for the locations of the objects was then tested with a change-detection task. Behavioral results confirmed the advantage for imagined viewpoint change compared with imagined array rotation of equivalent size. Encoding of object locations was associated with a network of areas, including bilateral superior and inferior parietal cortices. The precuneus was additionally activated by the demands of both viewpoint- and array rotation. The parieto-occipital sulcus/retrosplenial cortex and hippocampus were additionally activated by the demands of viewpoint rotation, while array rotation was associated with activation of the right intraparietal sulcus. These findings support a computational model of spatial memory in which parieto-occipital sulcus/retrosplenial cortex mediates spatial updating as part of a process of translation between "egocentric" and "allocentric" reference frames.

Is there a place for fear of blushing in social anxiety spectrum?

BACKGROUND: Fear of blushing (FB) in front of other people is a frequent and potentially incapacitating problem, but is not yet described as a specific diagnosis in psychiatric classifications. This can be explained by a lack of comparative studies with other forms of social anxiety disorder (SAD). Our aim was thus to explore the specificity of FB in patients with SAD. METHODS: SAD patients with FB but without other social threat (n = 142), the majority of whom were referred by a department of surgery after an initial request of sympathetic block for facial blushing, were compared to SAD patients with FB and other associated social fears (n = 97), and to SAD patients without FB (n = 190). They were assessed and compared with a structured diagnostic interview for DSM-IV and various scales measuring social anxiety, other anxiety and depressive symptoms, impairment and personality traits. RESULTS: The group with pure FB showed specific profiles when compared with the two other groups: later age of onset, less comorbidity, lower behavioral and temperamental inhibition, and higher self-esteem. However, their levels of social anxiety and impairment were high. No important differences appeared between the two other groups. CONCLUSION: The specificity of FB should be considered in the social anxiety spectrum, and could be viewed either as a SAD subtype or as SAD form secondary to facial blushing. Further epidemiological and therapeutic studies on this disorder are necessary.

Therapeutic drug monitoring of clomipramine and amitriptyline in a depressed patient with upper digestive tract resection.

We describe a 55-year-old woman with extensive digestive resection and recurrent depressive disorder resistant to oral clomipramine tablets but not to an oral solution of amitriptyline. In the light of this case report, the potential mechanisms of drug resistance after digestive resection are discussed, including the importance of drug monitoring.

Retrospective review of clozapine in the treatment of patients with autism spectrum disorder and severe disruptive behaviors.

Autism spectrum disorder (ASD) is a serious childhood-onset disorder in which social and language development are primarily affected, with associated repetitive behavior and, in some patients, behavioral symptoms including aggression and self-injury. In ASD, risperidone and aripiprazole are the only second-generation antipsychotic drugs that have shown to decrease disruptive behaviors in large-scale, controlled, double-blind studies. However, in some patients, these medications are not effective. Clozapine, a second-generation antipsychotic drug known to be effective in the treatment of aggression associated with schizophrenia, has received little attention in ASD.We conducted a retrospective analysis of the changes in disruptive behaviors for all patients with ASD treated with clozapine from 2002 to 2010. Disruptive behaviors were monitored during the 4 to 6 months before and after the initiation of clozapine. Long-term tolerance (10 months to 7 years) was also assessed. The relationship between disruptive behaviors and period of treatment (before and after clozapine) was studied with a generalized linear marginal model. Clozapine resulted in a significant 2-fold decrease in the number of the days with aggression, a decrease in the number of psychotropic drugs, and a decrease in the dose of the antipsychotic drugs. The long-term tolerance of clozapine (white blood cell count and extrapyramidal effects) was good, with the exception of significant weight gain (14.3 ± 10.9 kg), the occurrence of metabolic syndrome in 1 patient, and tachycardia in another patient.These results suggest that clozapine should be considered for the management of disruptive behaviors in patients with ASD not improved by first-line antipsychotic drugs.

Gender differences in the use of external landmarks versus spatial representations updated by self-motion.

Numerous data in the literature provide evidence for gender differences in spatial orientation. In particular, it has been suggested that spatial representations of large-scale environments are more accurate in terms of metric information in men than in women but are richer in landmark information in women than in men. One explanatory hypothesis is that men and women differ in terms of navigational processes they used in daily life. The present study investigated this hypothesis by distinguishing two navigational processes: spatial updating by self-motion and landmark-based orientation. Subjects were asked to perform a pointing task in three experimental conditions, which differed in terms of reliability of the external landmarks that could be used. Two groups of subjects were distinguished, a mobile group and an immobile group, in which spatial updating of environmental locations did not have the same degree of importance for the correct performance of the pointing task. We found that men readily relied on an internal egocentric representation of where landmarks were expected to be in order to perform the pointing task, a representation that could be updated during self-motion (spatial updating). In contrast, women seemed to take their bearings more readily on the basis of the stable landmarks of the external world. We suggest that this gender difference in spatial orientation is not due to differences in information processing abilities but rather due to the differences in higher level strategies.

Combination of conflicting visual and non-visual information for estimating actively performed body turns in virtual reality.

Whereas constant-weight linear models suffice for understanding many phenomena in the domain of perception and action, how the weights given to each sensory input are determined remains an open question. Notably, it has been suggested that weighting depends on the sensory context (e.g. the inconsistency between sensory signals) as well as on the subject. In the present study, the problem of non-linearity in multisensory interaction for estimating actively performed body turns was addressed at the level of group and individual data. Standing subjects viewed a virtual corridor in which forward movements were simulated at a constant linear velocity, and rotations were actually performed. Subjects were asked to learn the trajectory and then reproduce it from memory in total darkness. In the baseline condition, the relative amplitudes of visual and non-visual information for the performed rotations were the same, but were systematically manipulated in six 'sensory conflict' conditions. The subjects performed the task in these seven conditions 10 times (10 sessions), with a delay of at least 2 days between sessions. Five subjects placed more weight on visual than on non-visual information. The other 5 subjects placed more weight on non-visual than on visual information. Interestingly, the difference between 'visual' and 'non-visual' subjects in their use of conflicting information seemed to be accentuated by the fact of becoming aware of the sensory conflict. In all subjects, conflicting sensory inputs were combined in a linear way in order to estimate the angular displacements. However, signatures of non-linearity were detected when the data corresponding to the day on which subjects became aware of the conflict were considered in isolation. The present findings support the hypothesis that subjects used conflicting visual and non-visual information differently according to individual 'perceptive styles' (bottom-up processes) and that these 'perceptive styles' were made more observable by the subjects changing their perceptive strategy, i.e. re-weighting (top-down processes).

Influence of a sensorimotor conflict on the memorization of a path traveled in virtual reality.

Studies of visual-vestibular and vestibular-proprioceptive interactions suggest that prolonged exposure to sensory conflicts induces a modification of the relation between sensory modalities for self-motion perception. With most models conflicts are solved by a weighting process. However, the brain could also switch between conflicting cues. The present study focused on the effect of mismatched visual and non-visual information on the reproduction of actively performed turns. Standing subjects viewed a virtual corridor in which forward movements were simulated at a constant linear velocity, and rotations were actually performed. They were asked to learn the trajectory and then to reproduce it from memory in total darkness. In the baseline condition, the relative amplitudes of visual and non-visual information for the rotations performed were the same, but were manipulated in the two 'sensory conflict' conditions. The results show that even when subjects did not notice the sensory conflict, the discrepancy between visual and non-visual information affected their ability to reproduce the angular displacements. In one conflict condition, subjects relied on visual information when asked to draw the trajectory traveled, yet reproduced rotations on the basis of non-visual information during active blindfolded movements. This dissociation suggests that for mental simulation of the same path, there are at least two cognitive strategies of memory storage and retrieval, using either visual or non-visual information, according to the task and the sensory context.