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: 10.26). 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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    • "We hypothesized that, at resting state, children with ASD would exhibit increased low-and highfrequency brain activities in the frontal and sensorimotor cortices. This hypothesis is based on the observation that the brain generate signals up to 2884 Hz [17] and previous reports children with ASD have aberrant activity and abnormal development in the sensorimotor/ frontal cortices [18] [19] [20], which has been associated with sensory and motor symptoms. A previous study [2] revealed little about temporal resolution with analysis of up to 120 Hz [2]. "
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    ABSTRACT: The abnormality of intrinsic brain activity in autism spectrum disorders (ASDs) is still inconclusive. Contradictory results have been found pointing towards hyper-activity or hypo-activity in various brain regions. The present research aims to investigate the spatial and spectral signatures of aberrant brain activity in an unprecedented frequency range of 1-2884Hz at source levels in ASD using newly developed methods. Seven ASD subjects and age- and gender-matched controls were studied using a high-sampling rate magnetoencephalography (MEG) system. Brain activity in delta (1-4Hz), theta (4-8Hz), alpha (8-12Hz), beta (12-30Hz), low gamma (30-55Hz), high gamma (65-90Hz), ripples (90-200Hz), high-frequency oscillations (HFOs, 200-1000Hz), and very high-frequency oscillations (VHFOs, 1000-2884Hz) was volumetrically localized and measured using wavelet and beamforming. In comparison to controls, ASD subjects had significantly higher odds of alpha activity (8-12Hz) in the sensorimotor cortex (mu rhythm), and generally high-frequency activity (90-2884Hz) in the frontal cortex. The source power of HFOs (200-1000Hz) in the frontal cortex in ASD was significantly elevated as compared with controls. The results suggest that ASD has significantly altered intrinsic brain activity in both low- and high-frequency ranges. Increased intrinsic high-frequency activity in the frontal cortex may play a key role in ASD. Copyright © 2015 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.
    Brain and Development 04/2015; DOI:10.1016/j.braindev.2015.04.007 · 1.88 Impact Factor
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    • "Interestingly, morphometric studies in ASD draw an inconclusive picture on hippocampal volume in this disorder [9]. However, the frontal cortex, including the orbitofrontal region, has been shown to be a main target area of early brain overgrowth in ASD [10]. In addition, malformations in the frontal cortex through neuroinflammatory responses or migration defects seem to persist regardless of developmental influences [11]. "
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    ABSTRACT: Please cite this article in press as: Pehrs C, et al. The quartet theory: Implications for autism spectrum disorder. Phys Life Rev (2015), http://dx.
    Physics of Life Reviews 04/2015; DOI:10.1016/j.plrev.2015.04.025 · 7.48 Impact Factor
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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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    ABSTRACT: Atypical sensory responses are common in autism spectrum disorder (ASD). While evidence suggests impaired auditory-visual integration for verbal information, findings for nonverbal stimuli are inconsistent. We tested for sensory symptoms in children with ASD (using the Adolescent/Adult Sensory Profile) and examined unisensory and bisensory processing with a nonverbal auditory-visual paradigm, for which neurotypical adults show bisensory facilitation. ASD participants reported more atypical sensory symptoms overall, most prominently in the auditory modality. On the experimental task, reduced response times for bisensory compared to unisensory trials were seen in both ASD and control groups, but neither group showed significant race model violation (evidence of intermodal integration). Findings do not support impaired bisensory processing for simple nonverbal stimuli in high-functioning children with ASD.
    Journal of Autism and Developmental Disorders 02/2015; 5. DOI:10.1007/s10803-015-2367-z · 3.34 Impact Factor
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