11月8日,美國研究人員公布了一項小型研究結(jié)果顯示,，與普通兒童相比,，自閉癥患兒大腦前額葉皮層的神經(jīng)元數(shù)量過多,。這項發(fā)現(xiàn)有助理解自閉癥的病因,。
前額葉皮層是大腦中最重要的區(qū)域之一，參與人體的語言,、交流,、社會行為、情緒以及注意力等高級功能,。自閉癥患兒的這些高級功能通常有所欠缺,。
美國加利福尼亞州圣迭戈大學(xué)的研究人員對7名自閉癥患兒及6名普通男孩的前額葉皮層進(jìn)行了檢查,，這些男孩的年齡在2至16歲之間。結(jié)果發(fā)現(xiàn),，自閉癥患兒前額葉的神經(jīng)元數(shù)量比普通兒童多67%,，其平均腦重量也更重。
這項研究成果9日將發(fā)表在新一期《美國醫(yī)學(xué)會雜志》上,。研究人員表示,，由于皮層神經(jīng)元在患兒出生前而不是出生后產(chǎn)生，這表明自閉癥的出現(xiàn)可能與患兒胎兒期的神經(jīng)細(xì)胞生長或維持出現(xiàn)錯誤有關(guān),，另一個導(dǎo)致患兒神經(jīng)元過多的可能因素是其細(xì)胞凋亡機(jī)制出現(xiàn)紊亂,。（生物谷 Bioon.com)
doi:10.1001/jama.2011.1638
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Neuron Number and Size in Prefrontal Cortex of Children With Autism
Courchesne, Eric; Mouton, Peter R.; Calhoun, Michael E.; Semendeferi, Katerina; Ahrens-Barbeau, Clelia; Hallet, Melodie J.; Barnes, Cynthia Carter; Pierce, Karen
Context Autism often involves early brain overgrowth, including the prefrontal cortex (PFC). Although prefrontal abnormality has been theorized to underlie some autistic symptoms, the cellular defects that cause abnormal overgrowth remain unknown.
Objective To investigate whether early brain overgrowth in children with autism involves excess neuron numbers in the PFC.
Design, Setting, and Cases Postmortem prefrontal tissue from 7 autistic and 6 control male children aged 2 to 16 years was examined by expert anatomists who were blinded to diagnostic status. Number and size of neurons were quantified using stereological methods within the dorsolateral (DL-PFC) and mesial (M-PFC) subdivisions of the PFC. Cases were from the eastern and southeastern United States and died between 2000 and 2006.
Main Outcome Measures Mean neuron number and size in the DL-PFC and M-PFC were compared between autistic and control postmortem cases. Correlations of neuron number with deviation in brain weight from normative values for age were also performed.
Results Children with autism had 67% more neurons in the PFC (mean, 1.94 billion; 95% CI, 1.57-2.31) compared with control children (1.16 billion; 95% CI, 0.90-1.42; P = .002), including 79% more in DL-PFC (1.57 billion; 95% CI, 1.20-1.94 in autism cases vs 0.88 billion; 95% CI, 0.66-1.10 in controls; P = .003) and 29% more in M-PFC (0.36 billion; 95% CI, 0.33-0.40 in autism cases vs 0.28 billion; 95% CI, 0.23-0.34 in controls; P = .009). Brain weight in the autistic cases differed from normative mean weight for age by a mean of 17.6% (95% CI, 10.2%-25.0%; P = .001), while brains in controls differed by a mean of 0.2% (95% CI, −8.7% to 9.1%; P = .96). Plots of counts by weight showed autistic children had both greater total prefrontal neuron counts and brain weight for age than control children.
Conclusion In this small preliminary study, brain overgrowth in males with autism involved an abnormal excess number of neurons in the PFC.
