Early infantile autism.

Children's Neurology Service, Massachusetts General Hospital, Boston 02114, USA.
International Review of Neurobiology (Impact Factor: 2.46). 02/1997; 41:367-86.
Source: PubMed
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    ABSTRACT: This project assessed dyspraxia in high-functioning school aged children with autism with a focus on Ideational Praxis. We examined the association of specific underlying motor function including eye movement with ideational dyspraxia (sequences of skilled movements) as well as the possible role of visual-motor integration in dyspraxia. We found that compared to IQ-, sex- and age-matched typically developing children, the children with autism performed significantly worse on: Ideational and Buccofacial praxis; a broad range of motor tests, including measures of simple motor skill, timing and accuracy of saccadic eye movements and motor coordination; and tests of visual-motor integration. Impairments in individual children with autism were heterogeneous in nature, although when we examined the praxis data as a function of a qualitative measure representing motor timing, we found that children with poor motor timing performed worse on all praxis categories and had slower and less accurate eye movements while those with regular timing performed as well as typical children on those same tasks. Our data provide evidence that both motor function and visual-motor integration contribute to dyspraxia. We suggest that dyspraxia in autism involves cerebellar mechanisms of movement control and the integration of these mechanisms with cortical networks implicated in praxis.
    Behavioural brain research 04/2014; DOI:10.1016/j.bbr.2014.04.011 · 3.39 Impact Factor
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    ABSTRACT: Autism is unique among other disorders in that acquisition of conditioned eyeblink responses is enhanced in children, occurring in a fraction of the trials required for control participants. The timing of learned responses is, however, atypical. Two animal models of autism display a similar phenotype. Researchers have hypothesized that these differences in conditioning reflect cerebellar abnormalities. The present study used computer simulations of the cerebellar cortex, including inhibition by the molecular layer interneurons, to more closely examine whether atypical cerebellar processing can account for faster conditioning in individuals with autism. In particular, the effects of inhibitory levels on delay eyeblink conditioning were simulated, as were the effects of learning-related synaptic changes at either parallel fibers or ascending branch synapses from granule cells to Purkinje cells. Results from these simulations predict that whether molecular layer inhibition results in an enhancement or an impairment of acquisition, or changes in timing, may depend on (1) the sources of inhibition, (2) the levels of inhibition, and (3) the locations of learning-related changes (parallel vs. ascending branch synapses). Overall, the simulations predict that a disruption in the balance or an overall increase of inhibition within the cerebellar cortex may contribute to atypical eyeblink conditioning in children with autism and in animal models of autism.
    Cognitive Affective & Behavioral Neuroscience 03/2014; DOI:10.3758/s13415-014-0263-1 · 3.21 Impact Factor
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    ABSTRACT: Autism is characterized by behavioral impairments in three main domains: social interaction; language, communication and imaginative play; and the range of interests and activities. However, neuronal processing studies have suggested that hyper-perception, hyper-attention, and enhanced memory, which may lie at the heart of most autistic symptoms. Pregnant Wistar rats were administered by either Valproic Acid (VPA, 500mg/kg) or Phosphate Buffer Saline (PBS) during fetal neural tube development on embryonic day 12.5. All offspring were subjected to various tests. The present study examined social interaction, repetitive behaviors, nociception and tactile threshold, anxiety as well as spatial memory. Histological analyses of cells in five regions of the hippocampus were done to determine neuronal density in both groups. A single intra-peritoneal injection of VPA to pregnant rats produced severe autistic-like symptoms in the offspring. The results showed significant behavioral impairments such as a lower tendency to initiate social interactions, enhanced stereotyped, repetitive behaviors, increased nociception threshold and anxiety at postnatal day (PND) 30 and PND 60. The Morris water maze learning paradigm revealed enhanced spatial memory at PND 60. Furthermore, histological analysis showed that the neuronal density in five separate regions of hippocampus (CA1, CA2, CA3, Dentate gyrus and Subiculum) were increased at PND 67. This work suggests that early embryonic exposure to VPA in rats provides a good model for several specific aspects of autism and should help to continue to explore pathophysiological and neuroanatomical hypotheses. This study provides further evidence to support the notion that spatial memory and hippocampal cell density are increased in this animal model of autism.
    Brain research 06/2013; DOI:10.1016/j.brainres.2013.06.024 · 2.83 Impact Factor