Brief Report: Postural Reactivity to Fast Visual Motion Differentiates Autistic from Children with Asperger Syndrome

Journal of Autism and Developmental Disorders. Jun, 2002  |  Pubmed ID: 12108625

The aim of the present study was to search for a sensorimotor marker (i.e., visuopostural tuning) that could be correlated with the severity of motor impairments in children with autistic spectrum disorders. Given that autistic children were previously reported to be posturally hyporeactive to visually perceived environmental motion in comparison with normal control children (Gepner et al., 1995), we sought to determine whether children with Asperger syndrome (AS) would share the same postural hyporeactivity to visual motion. Three autistic children with mild to severe motor impairments, three AS children with soft motor signs, and nine normal control children were tested for overall postural instability and postural reactivity to environmental motion. Results indicate, first, that overall postural instability is significantly reduced in autistic children compared with both AS and normal children. Second, although postural oscillations in the fore-aft axis become more attuned to the oscillation frequency of an immersive dynamic visual display as visual speed is increased, in both control and AS subjects, this is not the case in autistic children. Despite the small number of subjects tested in this study, our data confirm the existence of a visuopostural detuning in autistic children. Third, they argue for a correlation between visuopostural tuning and severity of motor signs in children with autistic spectrum disorders. Finally, they suggest a differentiation between children with autism and children with AS with regard to postural reactivity to fast visual motion. Neurophysiological implications of these results are discussed. In particular, a visuocerebellar pathway deficit hypothesis in autism is proposed.

Rapid Visual-motion Integration Deficit in Autism

Trends in Cognitive Sciences. Nov, 2002  |  Pubmed ID: 12457894

Inner and Outer Face Perception in Children with Autism

Child Neuropsychology : a Journal on Normal and Abnormal Development in Childhood and Adolescence. Dec, 2003  |  Pubmed ID: 14972707

Possible peculiarities in face perception in the autistic population were explored through two experiments. Fourteen autistic children (mean age=10 years 1 month) were individually matched to verbal mental age (VMA) and chronological age (CA) subjects. In a first experiment, subjects were to match faces on the basis of either their outer (hair, chin, ears) or their inner (eyes, nose, mouth) aspects. Autistic children performed equally well in both conditions, while VMA-matched children performed better in the outer than the inner part condition. In a second experiment, chimeric faces consisting of the outer part of an individual's face and the inner part of another individual's face were presented to the subjects. None of the groups showed a preference for neither the outer nor the inner part of the face in this condition. Results were discussed in terms of the existence of a local visual processing strategy in this population.

Spatial Frequency and Face Processing in Children with Autism and Asperger Syndrome

Journal of Autism and Developmental Disorders. Apr, 2004  |  Pubmed ID: 15162938

Two experiments were designed to investigate possible abnormal face processing strategies in children with autistic spectrum disorders. A group of 11 children with autism was compared to two groups of normally developing children matched on verbal mental age and on chronological age. In the first experiment, participants had to recognize faces on the basis of identity, emotion, gaze direction, gender, and lip reading. All aspects of face processing, except for identity matching, were deficient in the autistic population compared with controls. In the second study, children had to match faces on either high-(i.e., local facial features) or low-spatial frequency information (i.e., global configuration of faces). Contrary to the control subjects, children with autism showed better performance when using high rather than low spatial frequency, confirming face-processing peculiarities in this population.

Autism, Movement, and Facial Processing

The American Journal of Psychiatry. Sep, 2004  |  Pubmed ID: 15337675

Slowing Down Presentation of Facial Movements and Vocal Sounds Enhances Facial Expression Recognition and Induces Facial-vocal Imitation in Children with Autism

Journal of Autism and Developmental Disorders. Sep, 2007  |  Pubmed ID: 17029018

This study examined the effects of slowing down presentation of facial expressions and their corresponding vocal sounds on facial expression recognition and facial and/or vocal imitation in children with autism. Twelve autistic children and twenty-four normal control children were presented with emotional and non-emotional facial expressions on CD-Rom, under audio or silent conditions, and under dynamic visual conditions (slowly, very slowly, at normal speed) plus a static control. Overall, children with autism showed lower performance in expression recognition and more induced facial-vocal imitation than controls. In the autistic group, facial expression recognition and induced facial-vocal imitation were significantly enhanced in slow conditions. Findings may give new perspectives for understanding and intervention for verbal and emotional perceptive and communicative impairments in autistic populations.

Abnormal Cerebral Effective Connectivity During Explicit Emotional Processing in Adults with Autism Spectrum Disorder

Social Cognitive and Affective Neuroscience. Jun, 2008  |  Pubmed ID: 19015104

Several recent studies suggest that autism may result from abnormal communication between brain regions. We directly assessed this hypothesis by testing the presence of abnormalities in a model of the functional cerebral network engaged during explicit emotion processing in adults with high functioning autism or Asperger syndrome. Comparison of structural equation models revealed abnormal patterns of effective connectivity, with the prefrontal cortex as a key site of dysfunction. These findings provide evidence that abnormal long-range connectivity between structures of the 'social brain' could explain the socio-emotional troubles that characterize the autistic pathology.

Autism: a World Changing Too Fast for a Mis-wired Brain?

Neuroscience and Biobehavioral Reviews. Sep, 2009  |  Pubmed ID: 19559043

Disorders in verbal and emotional communication and imitation, social reciprocity and higher order cognition observed in individuals with autism spectrum disorders (ASD) are presented here as phenotypic expressions of temporo-spatial processing disorders (TSPDs). TSPDs include various degrees of disability in (i) processing multi-sensory dynamic stimuli online, (ii) associating them into meaningful and coherent patterns and (iii) producing real-time sensory-motor adjustments and motor outputs. In line with this theory, we found that slowing down the speed of facial and vocal events enhanced imitative, verbal and cognitive abilities in some ASD children, particularly those with low functioning autism. We then argue that TSPDs may result from Multi-system Brain Disconnectivity-Dissynchrony (MBD), defined as an increase or decrease in functional connectivity and neuronal synchronization within/between multiple neurofunctional territories and pathways. Recent functional magnetic resonance imaging (fMRI) and electrophysiological studies supporting MBD are outlined. Finally, we review the suspected underlying neurobiological mechanisms of MBD as evidenced in neuroimaging, genetic, environmental and epigenetic studies. Overall, our TSPD/MBD approach to ASD may open new promising avenues for a better understanding of neuro-physio-psychopathology of ASD and clinical rehabilitation of people affected by these syndromes.

Slowing Down the Presentation of Facial and Body Movements Enhances Imitation Performance in Children with Severe Autism

Journal of Autism and Developmental Disorders. Aug, 2011  |  Pubmed ID: 20960040

Imitation deficits observed among individuals with autism could be partly explained by the excessive speed of biological movements to be perceived and then reproduced. Along with this assumption, slowing down the speed of presentation of these movements might improve their imitative performances. To test this hypothesis, 19 children with autism, 37 typically-developing children and 17 children with Down syndrome were asked to reproduce facial and body movements presented on a computer at a normal/ecological and two slowed down speeds. Our main result showed that a subgroup of individuals with severe autism better reproduced the movements when presented slowly than at the ecological speed. This finding opens a new window for comprehension and rehabilitation of perceptual and imitative deficits in autism.