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Mirror neuron system (MNS) dysfunctions might underlie deficits in autism spectrum disorders (ASD). Diffusion tensor imaging based probabilistic tractography was conducted in 15 adult ASD patients and 13 matched, healthy controls. Fractional anisotropy (FA) was quantified to assess group differences in tract-related white matter microstructure of both the classical MNS route (mediating "emulation") and the alternative temporo-frontal route (mediating "mimicry"). Multiple linear regression was used to investigate structure-function relationships between MNS connections and ASD symptom severity. There were no significant group differences in tract-related FA indicating an intact classical MNS in ASD. Direct temporo-frontal connections could not be reconstructed challengeing the concept of multiple routes for imitation. Tract-related FA of right-hemispheric parieto-frontal connections was negatively related to autism symptom severity.

Altered sensory perception has been found in patients with autism spectrum disorders (ASD) and might be related to aberrant sensory perception thresholds. We used the well-established, standardized Quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain to investigate 13 somatosensory parameters including thermal and tactile detection and pain thresholds in 13 ASD adults and 13 matched healthy controls with normal IQ values. There were no group differences between somatosensory detection and pain thresholds. Two ASD patients showed paradoxical heat sensations and another two ASD subjects presented dynamic mechanical allodynia; somatosensory features that were absent in controls. These findings suggest that central mechanisms during complex stimulus integration rather than peripheral dysfunctions probably determine somatosensory alterations in ASD.

Dysfunctions of the human mirror neuron system have been postulated to underlie some deficits in autism spectrum disorders including poor imitative performance and impaired social skills. Using three reaction time experiments addressing mirror neuron system functions under simple and complex conditions, we examined 20 adult autism spectrum disorder participants and 20 healthy controls matched for age, gender and education. Participants performed simple finger-lifting movements in response to (1) biological finger and non-biological dot movement stimuli, (2) acoustic stimuli and (3) combined visual-acoustic stimuli with different contextual (compatible/incompatible) and temporal (simultaneous/asynchronous) relation. Mixed model analyses revealed slower reaction times in autism spectrum disorder. Both groups responded faster to biological compared to non-biological stimuli (Experiment 1) implying intact processing advantage for biological stimuli in autism spectrum disorder. In Experiment 3, both groups had similar "interference effects" when stimuli were presented simultaneously. However, autism spectrum disorder participants had abnormally slow responses particularly when incompatible stimuli were presented consecutively. Our results suggest imitative control deficits rather than global imitative system impairments.

Altered sensory perception has been found in patients with autism spectrum disorders (ASD) and might be related to aberrant sensory perception thresholds. We used the well-established, standardized Quantitative sensory testing (QST) protocol of the German Research Network on Neuropathic Pain to investigate 13 somatosensory parameters including thermal and tactile detection and pain thresholds in 13 ASD adults and 13 matched healthy controls with normal IQ values. There were no group differences between somatosensory detection and pain thresholds. Two ASD patients showed paradoxical heat sensations and another two ASD subjects presented dynamic mechanical allodynia; somatosensory features that were absent in controls. These findings suggest that central mechanisms during complex stimulus integration rather than peripheral dysfunctions probably determine somatosensory alterations in ASD., Author(s): Odette Fründt [sup.1] , Wiebke Grashorn [sup.1] , Daniel Schöttle [sup.2] , Ina Peiker [sup.3] [sup.4] , Nicole David [sup.4] , Andreas K. Engel [sup.4] , Katarina Forkmann [sup.1] [...]

Individuals with an autism spectrum disorder (ASD) show hallmark deficits in social perception. These difficulties might also reflect fundamental deficits in integrating visual signals. We contrasted predictions of a social perception and a spatial-temporal integration deficit account. Participants with ASD and matched controls performed two tasks: the first required spatiotemporal integration of global motion signals without social meaning, the second required processing of socially relevant local motion. The ASD group only showed differences to controls in social motion evaluation. In addition, gray matter volume in the temporal-parietal junction correlated positively with accuracy in social motion perception in the ASD group. Our findings suggest that social-perceptual difficulties in ASD cannot be reduced to deficits in spatial-temporal integration.

Mentalizing refers to making inferences about other people's mental states, whereas visuospatial perspective taking refers to inferring other people's viewpoints. Both abilities seem vital for social functioning; yet, their exact relationship is unclear. We directly compared mentalizing and visuospatial perspective taking in nineteen adults with Asperger syndrome (AS) and fifteen control participants with the same stimulus material. Stimuli depicted virtual characters surrounded by two different objects. Virtual characters expressed a preference for one of the objects indicated by facial expression, gestures or head/body orientation. Compared to controls, participants with AS showed significantly increased reaction times and decreased accuracy for mentalizing (i.e., when inferring the virtual character's preference from the character's nonverbal bodily cues). By contrast, there were no significant group differences in perspective taking (i.e., by mental own-body transformations). These findings demonstrate, first, specific deficits in AS when mental states have to be inferred from nonverbal social cues. Second, visuospatial perspective taking may not necessarily be related to social impairments occurring in autism spectrum disorders.

Deficits in social cognition and interaction, such as in mentalizing and imitation behavior, are hallmark features of autism spectrum disorders. Both imitation and mentalizing are at the core of the sense of agency, the awareness that we are the initiators of our own behavior. Little evidence exists regarding the sense of agency in autism. Thus, we compared high-functioning adults with autism to healthy control subjects using an action monitoring and attribution task. Subjects with autism did not show deficits in this task, yet they showed significant mentalizing deficits. Our findings indicate a dissociation between the sense of agency and ascription of mental states in autism. We propose that social-cognitive deficits in autism may arise on a higher level than that of action monitoring and awareness.

Individuals with an autism spectrum disorder (ASD) show hallmark deficits in social perception. These difficulties might also reflect fundamental deficits in integrating visual signals. We contrasted predictions of a social perception and a spatial-temporal integration deficit account. Participants with ASD and matched controls performed two tasks: the first required spatiotemporal integration of global motion signals without social meaning, the second required processing of socially relevant local motion. The ASD group only showed differences to controls in social motion evaluation. In addition, gray matter volume in the temporal-parietal junction correlated positively with accuracy in social motion perception in the ASD group. Our findings suggest that social-perceptual difficulties in ASD cannot be reduced to deficits in spatial-temporal integration. Keywords Autism * Asperger syndrome * Motion coherence * Animacy * Social perception * Voxel-based morphometry, Introduction Autism spectrum disorders (ASD) are characterized by pervasive deficits in the social domain, including lack of understanding others' mental states ('theory of mind'), reduced social interests and impaired social-emotional [...]

Individuals with autism often show a fragmented way of perceiving their environment, suggesting a disorder of information integration, possibly due to disrupted communication between brain areas. We investigated thirteen individuals with high-functioning autism (HFA) and thirteen healthy controls using the metastable motion quartet, a stimulus consisting of two dots alternately presented at four locations of a hypothetical square, thereby inducing an apparent motion percept. This percept is vertical or horizontal, the latter requiring binding of motion signals across cerebral hemispheres. Decreasing the horizontal distance between dots could facilitate horizontal percepts. We found evidence for altered horizontal binding in HFA: Individuals with HFA needed stronger facilitation to experience horizontal motion. These data are interpreted in light of reduced cross-hemispheric communication. (Contains 1 figure.)

Individuals with autism often show a fragmented way of perceiving their environment, suggesting a disorder of information integration, possibly due to disrupted communication between brain areas. We investigated thirteen individuals with high-functioning autism (HFA) and thirteen healthy controls using the metastable motion quartet, a stimulus consisting of two dots alternately presented at four locations of a hypothetical square, thereby inducing an apparent motion percept. This percept is vertical or horizontal, the latter requiring binding of motion signals across cerebral hemispheres. Decreasing the horizontal distance between dots could facilitate horizontal percepts. We found evidence for altered horizontal binding in HFA: Individuals with HFA needed stronger facilitation to experience horizontal motion. These data are interpreted in light of reduced cross-hemispheric communication. Keywords Apparent motion * Bistable perception * Binding * Interhemispheric communication * High-functioning autism, Introduction Although not part of diagnostic criteria, individuals with autism spectrum disorders (ASD) often report a fragmented way of perceiving or attending to the world (Frith 2003). They may show [...]