新研究找到孤独症儿童学新动作困难的原因
肯尼迪·克里格研究所（Kennedy Krieger Institute）和约翰·霍普金斯大学（Johns Hopkins University）医学院的研究人员在一项合作的研究项目中，对于孤独症的神经学基础有了重要的新发现。发表在《自然神经科学》杂志上的这项最新研究，分析了孤独症儿童和发育正常的儿童在学习使用一个新工具时肢体的运动模式。研究结果显示，孤独症儿童学习新动作的方式与正常儿童不同。与正常儿童相比，他们更多地依赖于内在的对肢体位置的感觉（本体觉），而较少依赖于外在的视觉信息。研究人员还发现，一个孩子对本体觉的依赖性越强，他在社交技能、运动技能、和模仿能力上的缺陷就越严重。
从过去的研究中，研究人员已经知道孤独症儿童在肢体运动方面有困难，而且这可能与大脑里学习肢体运动的功能异常有关。为了了解孤独症儿童学习新动作时大脑的工作模式，研究人员让14个孤独症儿童和13个发育正常的儿童学习使用一个新的工具，并对他们泛化所学技能的模式做了测量。然后，他们就孩子们的泛化能力从两个方面作出了分析：一是他们在多大程度上依赖于视觉信息，一是他们在多大程度上依赖于本体觉信息。
“我们的发现可能会对孤独症的治疗产生重要的影响。如果将这些知识付诸实用，就可以设计出有针对性的干预方法，帮助孤独症儿童在学习新技能时强化视觉和动作之间的联系。”肯尼迪·克里格研究所发育认知神经学系的儿童神经病专家和论文执笔Stewart H. Mostofsky博士说。“如果尽早干预，孤独症儿童的运动和社交能力的发展就可能得到改善。不仅如此，他们对社交意图的理解力也会增强，因为大脑里对建立动作的内在模型起关键作用的那部分系统，也对理解这些动作起关键的作用。”
曾经有一些研究认为，孤独症可能与大脑内部的连接异常有关。具体地说，就是连接相邻脑区域的脑白质过多，而连接相隔较远的脑区域的脑白质过少。而这项新的研究对此提供了支持。它的发现刚好与这种异常的连接模式相符，因为与本体觉有关的脑区域与动作区相距很近，而视觉-动作的信息处理则依赖于长距离的连接。
“这些发现不仅告诉我们为什么孤独症儿童学习运动技能有困难，而且揭示了这些孩子与环境互动困难的深层因素。”约翰·霍普金斯大学医学院的生物医学工程和神经科学教授、高级论文执笔Reza Shadmehr博士说。“如果他们大脑的连接方式使他们无法像正常儿童那样依赖外来的视觉信号控制自己的动作，他们就很难学习与别人互动，也很难明白别人的行为是什么意思。”
下一步的工作，可能包括利用神经成像技术来研究这种本体强于视觉的反馈方式是否确实与孤独症儿童大脑的结构和功能上的连接异常有关。另一个可能性，是研究通过改变动作的学习方式来增强大脑某些区域之间的视觉连接。研究人员正在考虑是否可以通过刺激大脑皮层、使用生物反馈疗法、行为疗法等干预手段，改善孤独症儿童用视觉信息来学习各种动作的能力。（英文版请看下一页）#p#分页标题#e#
New Study Pinpoints Difference in the Way Children with Autism Learn New Behaviors
Researchers from the Kennedy Krieger Institute and Johns Hopkins University School of Medicine have collaborated to uncover important new insights into the neurological basis of autism. Their new study, published in the journal Nature Neuroscience, examined patterns of movement as children with autism and typically developing children learned to control a novel tool. The findings suggest that children with autism appear to learn new actions differently than do typically developing children. As compared to their typically developing peers, children with autism relied much more on their own internal sense of body position (proprioception), rather than visual information coming from the external world to learn new patterns of movement. Furthermore, researchers found that the greater the reliance on proprioception, the greater the child’s impairment in social skills, motor skills and imitation.
Previous research has shown that children with autism have difficulty with motor skills, which appears to be associated with abnormalities in how the brain learns motor actions. To study the models formed in the brain when children with autism learn a new movement, researchers measured patterns of generalization as 14 children with autism and 13 typically developing children learned to reach using a novel tool. They then examined how well children were able to generalize what they learned in two separate ways – one that detected how much they relied on visual information to guide learning and one that detected how much they relied on proprioceptive information to guide learning.
“These findings can lead to important advances in methods for treating autism. Applying the knowledge gained in the current study, targeted interventions can be developed that enhance visuo-motor associations in children with autism as they learn new skills,” said Dr. Stewart H. Mostofsky, study author and a pediatric neurologist in the Department of Developmental Cognitive Neurology at the Kennedy Krieger Institute. “If done early enough, this could help to improve development of motor, social and communicative skills in children with autism. Further, it could also improve their ability to understand social cues because the brain systems critical to forming internal models of behavior that guide our actions are also critical to developing an understanding of the meaning of those actions.”
The study findings also provide support for observations from previous studies suggesting that autism may be associated with abnormalities in the wiring of the brain; specifically, with overdevelopment of short range white matter connections between neighboring brain regions and underdevelopment of longer distance connections between distant brain regions. The findings from this study are consistent with this pattern of abnormal connectivity, as the brain regions involved in proprioception are closely linked to motor areas, while visual-motor processing depends on more distant connections.
“These findings not only demonstrate why children with autism have difficulty learning motor skills, but also provide real insight into why these children have difficulty learning to interact with the world around them,” said Dr. Reza Shadmehr, senior study author and Professor of Biomedical Engineering and Neuroscience at the John Hopkins University School of Medicine. “If the way their brain is wired is not allowing them to rely as much as typically developing children on external visual cues to guide behavior, they may have difficulty learning how to interact with other people and interpret the nature of other people’s actions.”
Potential next steps include the use of neuroimaging to investigate whether or not proprioceptive versus visual feedback is actually associated with abnormal patterns of structural and functional connectivity in the brain of children with autism. Additionally, researchers may study if patterns of motor learning can be altered to increase visual connections in specific regions of the brain. Through interventions such as cortical stimulation, biofeedback and behavioral approaches, researchers are looking to investigate if there is an improvement in children with autism’s ability to rely on visual input to guide how they learn a range of behavioral skills.
