Article

Localized enlargement of the frontal lobe in autism. Biological Psychiatry, 57, 126-133

Center for Autism Research, Children's Hospital Research Center, and Neurosciences Department, University of California at San Diego, San Diego, California, USA.
Biological Psychiatry (Impact Factor: 10.25). 02/2005; 57(2):126-33. DOI: 10.1016/j.biopsych.2004.11.005
Source: PubMed

ABSTRACT Evidence from behavioral, imaging, and postmortem studies indicates that the frontal lobe, as well as other brain regions such as the cerebellum and limbic system, develops abnormally in children with autism. It is not yet clear to what extent the frontal lobe is affected; that is, whether all regions of frontal cortex show the same signs of structural maldevelopment.
In the present study, we measured cortical volume in four subregions of the frontal cortex in 2-year-old to 9-year-old boys with autism and normal control boys.
The dorsolateral region showed a reduced age effect in patients when compared with control subjects, with a predicted 10% increase in volume from 2 years of age to 9 years of age compared with a predicted 48% increase for control subjects. In a separate analysis, dorsolateral and medial frontal regions were significantly enlarged in patients aged 2 to 5 years compared with control subjects of the same age, but the precentral gyrus and orbital cortex were not.
These data indicate regional variation in the degree of frontocortical overgrowth with a possible bias toward later developing or association areas. Possible mechanisms for these regional differences are discussed.

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    • "However, a recent meta-analysis of functional neuroimaging evidence has been interpreted as indicating potential sparing of the visual domain in ASD (Samson et al. 2012; see also reviews by Milne et al. 2009, and Simmons et al. 2009). In addition, neuroanatomical studies suggest that visual regions in the occipital lobe may be spared with respect to early brain overgrowth and cytoachitectonic abnormalities observed in other forebrain lobes (Carper and Courchesne 2005; Palmen et al. 2004). Although expected atypical sensory behaviors were detected in the ASD group, our findings of sensory symptoms from the AASP were not as robust as reported in previous studies including younger children (Kientz and Dunn 1997; Tomchek and Dunn 2007). "
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