AN EVALUATION OF CAUSES FOR UNRELIABILITY OF SYNAPTIC TRANSMISSION
AN EVALUATION OF CAUSES FOR UNRELIABILITY OF SYNAPTIC TRANSMISSION
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DOI：
10.1073/pnas.91.22.10380
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发表时间：
1994-10-25
影响因子：
11.1
通讯作者：
STEVENS, CF
中科院分区：
文献类型：
--
作者：
ALLEN, C;STEVENS, CF
发现在CA1海马锥体神经元上的单个突触接触处的传播非常不可靠，超过一半到达的突触前神经冲动未能引起突触后反应。使用最小化Schaffer侧支和海马切片中整个细胞记录的方法得出了这一结论。在最小的刺激下，仅在目标神经元上激活一个或几个突触，并检查单个突触的行为tan。已经研究了突触传播不可靠性的四个来源：（i）刺激部位的轴突阈值波动，导致在适当的Schaffer侧支中产生神经冲动，（ii）神经冲动的失败在由于轴突分支点的传导失败而到达突触的位点，（iii）由于执行而导致的人为突触不可靠在温度下的体外实验远低于正常的哺乳动物体温，并且（iv）由于突触的概率释放机制而导致的（iv）传播失败，其释放发射器的能力非常低。我们消除了前三个原因，这是重大贡献，并得出结论，拖曳能力突触的概率释放机制是突触传播不可靠的主要原因。
Transmission at individual synaptic contacts on CA1 hippocampal pyramidal neurons has been found to be very unreliable, with greater than half of the arriving presynaptic nerve impulses failing to evoke a postsynaptic response. This conclusion has been reached using the method of minimal stimulation of Schaffer collaterals and whole cell recording in hippocampal slices; with minimal stimulation only one or a few synapses are activated on the target neuron and the behavior of individual synapses tan be examined. Four sources for the unreliability of synaptic transmission have been investigated: (i) the fluctuation of axon thresholds at the site of stimulation causing the failure to generate a nerve impulse in the appropriate Schaffer collaterals, (ii) the failure of nerve impulses generated at the site of stimulation to arrive at the synapse because of conduction failures at axon branch points, (iii) an artifactual synaptic unreliability due to performing experiments in vitro at temperatures well below the normal mammalian body temperature, and (iv) transmission failures due to probabilistic release mechanisms at synapses with a very low capacity to release transmitter. We eliminate the first three causes as significant contributions and conclude that probabilistic release mechanisms at tow capacity synapses are the main cause of unreliability of synaptic transmission.