Brain activity elicited by viewing pictures of the own virtually amputated body predicts xenomelia.

BACKGROUND: Xenomelia is a rare condition characterized by the persistent desire for the amputation of physically healthy limbs. Prior studies highlighted the importance of superior and inferior parietal lobuli (SPL/IPL) and other sensorimotor regions as key brain structures associated with xenomelia. We expected activity differences in these areas in response to pictures showing the desired body state, i.e. that of an amputee in xenomelia. METHODS: Functional magnetic resonance images were acquired in 12 xenomelia individuals and 11 controls while they viewed pictures of their own real and virtually amputated body. Pictures were rated on several dimensions. Multivariate statistics using machine learning was performed on imaging data. RESULTS: Brain activity when viewing pictures of one's own virtually amputated body predicted group membership accurately with a balanced accuracy of 82.58% (p = 0.002), sensitivity of 83.33% (p = 0.018), specificity of 81.82% (p = 0.015) and an area under the ROC curve of 0.77. Among the highest predictive brain regions were bilateral SPL, IPL, and caudate nucleus, other limb representing areas, but also occipital regions. Pleasantness and attractiveness ratings were higher for amputated bodies in xenomelia. CONCLUSIONS: Findings show that neuronal processing in response to pictures of one's own desired body state is different in xenomelia compared with controls and might represent a neuronal substrate of the xenomelia complaints that become behaviourally relevant, at least when rating the pleasantness and attractiveness of one's own body. Our findings converge with structural peculiarities reported in xenomelia and partially overlap in task and results with that of anorexia and transgender research.

Temporal Instabilities in Amblyopic Perception: A Quantitative Approach.

The purpose of this study is to quantify the temporal characteristics of spatial misperceptions in human amblyopia. Twenty-two adult participants with strabismus, strabismic, anisometropic, or mixed amblyopia were asked to describe their subjective percept of static geometrical patterns with different spatial frequencies and shapes, as seen with their non-dominant eye. We generated digital reconstructions of their perception (static images or movies) that were subsequently validated by the subjects using consecutive matching sessions. We calculated the Shannon entropy variation in time for each recorded movie, as a measure of temporal instability. Nineteen of the 22 subjects perceived temporal instabilities that can be broadly classified in two categories. We found that the average frequency of the perceived temporal instabilities is ∼1 Hz. The stimuli with higher spatial frequencies yielded more often temporally unstable perceptions with higher frequencies. We suggest that type and amount of temporal instabilities in amblyopic vision are correlated with the etiology and spatial frequency of the stimulus.

[Body integrity identity disorder--first success in long-term psychotherapy]. / Body Integrity Identity Disorder: Erste Erfolge in der Langzeitpsychotherapie.

OBJECTIVE: The Body Integrity Identity Disorder (BIID) is a fairly unknown and unexplored psychic illness. Very little cases underwent a psychotherapeutic treatment. METHODS: We report on the two-and-a-half year psychotherapy with a 37 years old man, who wants an amputation of his two legs. RESULTS: Origin and meaning of the amputation desire were uncovered in psychotherapy. CONCLUSIONS: The psychodynamic oriented therapy with cognitive-behavioral elements can be used to develop further treatment approaches.

Strabismic amblyopes show a bilateral rightward bias in a line bisection task: evidence for a visual attention deficit.

Neurologically normal observers show a consistent leftward bias when asked to bisect a horizontal line ("pseudoneglect"). In this study, we found that subjects with strabismic and strabismic-anisometropic amblyopia show a consistent rightward bias ("minineglect") in a line bisection task. The bias was seen in both eyes, but affected more strongly the amblyopic eye. Purely anisometropic amblyopes show a similar bias, affecting only the amblyopic eye. The group of strabismics with alternating fixation did not differ significantly from normal observers. These errors are reminiscent of the attentional neglect of the left extrapersonal space, shown by subjects with lesions in the right posterior parietal cortex. We suggest that an early strabismus might lead to a functional deficit of the dorsal cortical pathway, in addition to the well-known impairments on the ventral visual pathway. We conclude that strabismic amblyopes might show subtle attentional deficits, in addition to their unilateral vision loss.

Impaired serial visual search in children with developmental dyslexia.

In order to test the hypothesis of attentional deficits in dyslexia, we investigated the performance of children with developmental dyslexia on a number of visual search tasks. When tested with conjunction tasks for orientation and form using complex, letter-like material, dyslexic children showed an increased number of errors accompanied by faster reaction times in comparison to control children matched to the dyslexics on age, gender, and intelligence. On conjunction tasks for orientation and color, dyslexic children were also less accurate, but showed slower reaction times than the age-matched control children. These differences between the two groups decreased with increasing age. In contrast to these differences, the performance of dyslexic children in feature search tasks was similar to that of control children. These results suggest that children with developmental dyslexia present selective deficits in complex serial visual search tasks, implying impairment in goal-directed, sustained visual attention.

Patterns of spatial distortions in human amblyopia are invariant to stimulus duration and instruction modality.

We investigated the patterns of two-dimensional spatial distortions in human amblyopia, using three different psychophysical mapping procedures. Strabismic and strabismic-anisometropic amblyopes showed consistent distortions, consisting in enlargement, shrinkage, or torsion of portions of the tested visual field. Purely anisometropic amblyopes and strabismics with alternating fixation showed increased spatial uncertainty, but no consistent distortions. For all groups of subjects, there was a very good correspondence between the patterns of distortion obtained with the three methods. We conclude that the spatial distortions are robust across different procedures. They might reflect a genuine rearrangement of the cortical topography as a result of strabismus.