Scientists have known that abnormal brain growth is associated with autism spectrum1 disorder2. However, the relationship between the two has not been well understood. Now, scientists from the Florida campus of The Scripps Research Institute have shown that mutations in a specific gene3 that is disrupted in some individuals with autism results in too much growth throughout the brain, and yet surprisingly specific problems in social interactions, at least in mouse models that mimic4 this risk factor in humans. What was striking is that these were basically normal animals in terms of behavior, but there were consistent deficits5 in tests of social interaction and recognition -- which approximate a major symptom of autism, said Damon Page, a TSRI biologist who led the study. This suggests that when most parts of the brain are overgrown, the brain somehow adapts to it with minimal6 effects on behavior in general. However, brain circuits relevant to social behavior are more vulnerable or less able to tolerate this overgrowth.The study, which focuses on the gene phosphatase（磷酸酶） and tensin homolog , was recently published online ahead of print by the journal Human Molecular7 Genetics.Autism spectrum disorder is a neurodevelopmental disorder involving a range of symptoms and disabilities involving social deficits and communication difficulties, repetitive behaviors and interests, and sometimes cognitive8 delays. The disorder affects in approximately one percent of the population; some 80 percent of those diagnosed are male.In a previous study, Page and colleagues found that mutations in Pten causes increased brain size and social deficits, with both symptoms being exacerbated9 by a second hit to a gene that regulates levels of the neurotransmitter serotonin（血清素） in the brain. In the new study, the TSRI team set out to explore whether mutations in Pten result in widespread or localized overgrowth within the brain, and whether changes in brain growth are associated with broad or selective deficits in tests of autism-relevant behaviors in genetically10 altered mice. The team tested mice for autism spectrum disorder-related behaviors including mood, anxiety, intellectual, and circadian rhythm and/or sleep abnormalities.The researchers found that Pten mutant mice showed altered social behavior, but few other changes -- a more subtle change than would have been predicted given broad expression and critical cellular11 function of the gene.Intriguingly12, some of the more subtle impairments were sex-specific. In addition to social impairments, males with the mutated gene showed abnormalities related to repetitive behavior and mood/anxiety, while females exhibited additional circadian activity and emotional learning problems.The results raise the question of how mutations in PTEN, a general regulator of growth, can have relatively13 selective effects on behavior and cognitive development. One idea is that PTEN mutations may desynchronize the normal pattern of growth in key cell types -- the study points to dopamine neurons -- that are relevant for social behavior.Timing14 is everything, Page said. Connections have to form in the right place at the right time for circuits to develop normally. Circuitry involved in social behavior may turn out to be particularly vulnerable to the effects of poorly coordinated15 growth.
点击收听单词发音
1 spectrum n.谱，光谱，频谱；范围，幅度，系列 参考例句： This is a kind of atomic spectrum.这是一种原子光谱。 We have known much of the constitution of the solar spectrum.关于太阳光谱的构成，大家已知道不少。
相关文章推荐
