Development of Selective Connectivity in a Simple Nervous System

神经细胞或神经元在称为突触的特殊连接处相互交流。在化学突触中，活跃的神经元从末端的突触前一侧释放一种特殊的化学神经递质化合物，穿过微小的突触间隙，与突触后细胞上的受体分子结合。神经递质的结合导致称为突触后电位的电生理变化。电生理记录可以测量递质释放的两个敏感指标是促进，这是一种增加的突触后反应，以及抑制，这是一种减少的突触后反应。在昆虫中，一些已确定的单细胞可以在突触后细胞上形成两种不同的突触，在一种细胞上促进而在另一种细胞上抑制。突触易化的出现被发现是由突触后细胞调节的，所以目标细胞对它接收到的输入有影响。这项工作将利用电生理学和药理学来研究这种递质释放的逆行调节，利用无脊椎动物神经系统具有特定可识别突触的优势。这可能是一种共同递质的持续释放差异调节突触前末端的特性，或者是突触后神经元释放一种调节突触前末端功能的物质。这项工作的结果对于理解突触活动是如何调节的重要问题将是重要的，这些结果可能在神经生理学和发育神经科学中都有广泛的影响。

Murphey 9514701 Nerve cells, or neurons, communicate with each other at specialized junctions called synapses. At chemical synapses, an active neuron releases a particular chemical neurotransmitter compound from the presynaptic side of the terminal to cross the tiny synaptic gap and bind to receptor molecules on the postsynaptic cell. Binding of the neurotransmitter leads to an electrophysiological change called the postsynaptic potential. Two sensitive indicators of transmitter release that can be measured by electrophysiological recordings are facilitation, which is an increased postsynaptic response, and depression, which is a decreased postsynaptic response. Some identified single cells in insects can make two different kinds of synapse on postsynaptic cells, facilitating at one cell and depressing at the other. The emergence of facilitation at a synapse has been found to be regulated by the postsynaptic cell, so the target cell has an effect on the input it receives. This work will use electrophysiology and pharmacology to examine this retrograde regulation of transmitter release, using the advantages of invertebrate nervous systems in having particular identifiable synapses. It may be that a continuous release of a co-transmitter differentially adjusts the properties of the presynaptic terminal, or instead that the postsynaptic neurons release a substance that regulates the function of the presynaptic terminal. Results from this work will be important to understanding the important issue of how synaptic activity is regulated, and these results are likely to have a broad impact in both neurophysiology and developmental neuroscience.