脑部磁场揭露孤独症患者语言障碍
Faint magnetic signals from brain activity in children with autism show that those children process sound and language differently from non-autistic children. Identifying and classifying these brain response patterns may allow researchers to more accurately diagnose autism and possibly aid in developing more effective treatments for the developmental disorder.
Timing appears to be crucial. "Children with autism respond a fraction of a second more slowly than healthy children to vowel sounds and tones," said study leader Timothy Roberts, Ph.D., vice chair of radiology research and holder of the Oberkircher Family Endowed Chair in Pediatric Radiology at The Children's Hospital of Philadelphia. Roberts used a technology called magnetoencephalography (MEG), which detects magnetic fields in the brain, just as electroencephalography (EEG) detects electrical fields.
Roberts presented his findings today at the annual meeting of the Radiological Society of North America in Chicago. "The brain's electrical signals generate tiny magnetic fields, which change with each sensation, and with communication among different locations in the brain," he added.
Roberts is working to develop "neural signatures" that can link recorded brain activity to particular behaviors in children with autistic spectrum disorders (ASDs), which are characterized by impaired development in communications and social functioning. "Our hypothesis is that speech and other sounds come in too fast for children with ASDs, and their difficulties in processing sound may impair their language and communication skills," said Roberts.
Physicians already use MEG to map the locations of abnormal brain activity in epilepsy, but the technology Roberts used is one of the few MEG machines available in a dedicated pediatric facility. In the current study, the researchers evaluated 64 children aged six to 15 at The Children's Hospital of Philadelphia. Thirty children had ASDs, the rest were age-matched, typically developing control subjects.
The MEG machine has a helmet that surrounds the child's head. The researchers presented a series of recorded beeps, vowels and sentences. As the child's brain responded to each sound, noninvasive magnetic detectors in the machine analyzed the brain's changing magnetic fields.
When sounds were presented, the MEG recorded a delay of 20 milliseconds (1/50 of a second) in the brain's response for children with ASDs, when compared with healthy control subjects. "This delay indicates that auditory processing is abnormal in children with autism, and may lead to a cascade of delay and overload in further processing of sound and speech," said Roberts. "Further research may shed light on how this delay in processing sounds may be related to interconnections among parts of the brain." Other testing, measuring a response to mismatched or changed sounds, found longer delays, up to 50 milliseconds (1/20 of a second).
Because autism disorders range across a spectrum of functional abilities, explained Roberts, neural signatures based on brain responses may allow clinicians to more accurately diagnose which subtype of ASD an individual patient has. Such diagnoses may be possible at an earlier age if future studies show that such signatures are detectable in infancy—at younger ages than in the children involved in the current study. "Earlier diagnosis of ASDs may allow clinicians to intervene earlier with possible treatments," said Roberts.
Furthermore, added Roberts, if a patient's neural signature overlaps with that found in another neurological condition, such as epilepsy or attention-deficit hyperactivity disorder, for which a treatment exists, that patient may benefit from such a treatment.
The National Institutes of Health, the Nancy Lurie Marks Family Foundation, and the Jeffrey and Christina Lurie Family Foundation provided funding support for the study. Co-authors with Roberts were J. Christopher Edgar, Ph.D.; Deborah M. Zarnow, M.D.; and Susan E. Levy, M.D.; all of Children's Hospital.
从患孤独症的儿童采集的脑部活动微弱的核磁共振信号显示他们比正常儿童有着不同的声音和语言加工能力。确认和分类这些脑的反映模式能帮助研究者更准确地诊断孤独症，同时也能帮助找到更有效的治疗发育紊乱的手段。时机最重要，放射学研究副主席、Oberkircher家族资助的费城儿童医院儿科放射学的的负责人、学科带头人Timothy Roberts博士说，“孤独症的小孩对元音和声调的反应要比正常小孩慢不到一秒钟，他利用了一个叫作脑磁波描记术的技术，该技术能扫描脑的磁场，就象脑电描记法扫描电场一样。
今天他在芝加哥召开的每年一届的北美放射学大会上陈述了自己的发现，“脑的电信号能产生微弱的场，伴随每一次感觉冲动和不同的脑区交互作用它就会有改变，Roberts正在开发“神经元信号”，用它可以将脑的活动记录与泛自闭症障碍症（特征是一种发育性交流和社交功能障碍）儿童的特定行为联系起来，他说“我们的假设是，语言和其他声音对该疾病儿童太快了，他们对声音处理的困难能损害他们自己的语言与沟通能力。”
医生们已经利用脑磁波描记术去定位癫痫病人异常的脑活动，但是Roberts用的是儿科专用的其中一台。在该研究中，研究人员评价了64位6到15岁的费城儿童医院的儿童，他们中有30位患有孤独症，其余的是年龄相仿的、有代表性的发育正常儿童。该机器有一个头盔戴在小孩子的头上，研究人员发出一系列嘟嘟声、元音与整个句子，当测试者对每个声音做出反应时，这种非侵入式的机器就能分析脑中磁场的改变。当声音发出的时候，机器能记录相对于正常儿童有20毫秒的时间延迟的患孤独症儿童的脑反应。“这种延迟提示了患病儿童听觉加工方面的异常，可能导致了一系列延迟和随后的声音和语言的加工过载”，Roberts说，“进一步研究可能揭示这种声音加工的延迟与各脑区的交互连接之间是怎样联系的。”别的测试，包括检测对错误搭配和声音改变的反应，找到更长的延迟，直到50毫秒的时间。
Roberts 解释道，因为孤独症的范围包括一系列功能活动，依据脑反应的神经元信号可能使临床人员更准确地诊断某个病人是什么类型的孤独症。如果将来可以在婴儿期就能检测到这样的信号，就可以在更早的时期诊断该疾病的发生，比现在儿童确诊的年龄还要小。“早期诊断能使医生尽可能多的手段的干预该疾病。”而且，如果病人的神经信号与其他神经功能信号重叠，如癫痫或者注意缺陷障碍，而且他们又处在治疗干预中，他们就能从这些干预中获益。美国国立卫生研究院、Nancy Lurie Marks家族基金会与Jeffrey、Christina Lurie 家族基金会为该项研究提供支持，Roberts的共同作者是J. Christopher Edgar博士、Deborah M. Zarnow博士和Susan E. Levy博士，他们都来自费城儿童医院。
