Synaptic Plasticity at the Mammalian Neuromuscular Junction

在正常的出生后发育过程中，哺乳动物骨骼肌经历了一个有序的突触消除过程，即每条肌肉纤维开始时处于多神经支配状态，但最终失去了除一条输入外的所有输入。Van Essen博士将研究兔比目鱼肌突触消除和连接可塑性的几个方面。在一系列项目中，范·埃森博士和他的同事将研究神经和肌肉活动在突触消除过程中的作用。先前的研究表明，活动的增加加速了突触消除的总体速度，而竞争突触之间的不同活动则赋予了不那么活跃的输入优势。Van Essen博士感兴趣的是阐明活动产生这些双重影响的机制，以及确定自然活动模式是否有助于塑造成人运动单元大小的分布。另一组项目旨在了解纤维类型特异性的基础，即快速和缓慢收缩的肌肉纤维选择性地由快速和慢速运动神经元支配。在过去的十年里，Van Essen博士在这一领域做出了许多重要的贡献。这些新研究的结果肯定会为突触消除这一重要的发育现象提供基础信息。

During normal postnatal development, mammalian skeletal muscles undergo an orderly process of synapse elimination, whereby each muscle fiber begins in a state of polyinnervation but eventually loses all except one of its inputs. Dr. Van Essen will study several aspects of synapse elimination and plasticity of connections in the soleus muscle of the rabbit. In one set of projects, Dr. Van Essen and his colleagues will examine the role of nerve and muscle activity in this process of synapse elimination. Previous studies have shown that increased activity accelerates the overall rate of synapse elimination, while differential activity among competing synapses confers an advantage to the less active inputs. Dr. Van Essen is interested in clarifying the mechanisms whereby activity exerts these dual influences and also in ascertaining whether natural activity patterns contribute to sculpting of the distribution of motor unit sizes in the adult. Another set of projects is aimed at understanding the basis of fiber-type specificity, whereby fast- and slow-contracting muscle fibers are selectively innervated by fast and slow motor neurons. Dr. Van Essen has made a number of important contributions to this field over the past ten years. The results of these new studies will certainly add fundamental information about the important developmental phenomenon of synapse elimination.