ANALYSIS OF SYNAPTIC DEPRESSION CONTRIBUTING TO HABITUATION OF GILL-WITHDRAWAL REFLEX IN APLYSIA-CALIFORNICA
ANALYSIS OF SYNAPTIC DEPRESSION CONTRIBUTING TO HABITUATION OF GILL-WITHDRAWAL REFLEX IN APLYSIA-CALIFORNICA
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DOI：
10.1152/jn.1982.48.2.431
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发表时间：
1982-01-01
影响因子：
2.5
通讯作者：
BYRNE, JH
中科院分区：
文献类型：
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作者：
BYRNE, JH
对虹吸皮肤的反复刺激会导致鳃反射收缩的短期习惯化。习惯化又与机械感觉神经元(SN)运动神经元兴奋性突触后电位(EPSP)的抑制有关。这项研究检查了突触抑制的参数特征，以深入了解递质释放减少的机制。用去极化电流脉冲重复诱发单个感觉神经元动作电位，同时监测运动神经元EPSP的幅度。突触抑制是刺激间期(ISI)的复杂函数。在ISI为1的S，抑郁是迅速的，并在对照组的36%达到平台期。在ISI100时，S的抑郁没有那么明显，表现出逐渐衰退到第10个EPSP控制组的65%。在很大范围的中等ISI(3，10和30 S)上，抑郁的时间进程或程度没有显著差异，尽管这些ISI的抑郁是介于1-100 S ISI之间的。棘波间期与2个EPSP中第2个的压低之间也存在复杂的关系。EPSP第二波或一串EPSP波的压低不是峰间期的单调函数。可能有一个轻微的潜在促进过程，具有较短的尖峰间隔。在一系列10次刺激后，突触抑制的恢复并不是一成不变的；更短的棘波间隔会产生更快的恢复。这些数据与经典的突触抑制耗竭模型不一致，表明突触抑制及其在感觉神经元突触处的恢复要么是时间和ISI的单一复杂功能，要么是多种功能的基础。
Repeated stimulation of the siphon skin results in short-term habituation of the reflex contractions of the gill. The habituation, in turn, is correlated with a depression of the excitatory postsynaptic potentials (EPSP) in motor neurons from mechanoreceptor sensory neurons (SN). This study examined the parametric features of the synaptic depression to gain insights into the mechanisms underlying the reduced transmitter release. Single sensory neuron action potentials were repeatedly elicited with depolarizing current pulses while the amplitude of the resultant EPSP in the motor neuron was monitored. Synaptic depression varies as a complex function of interstimulus interval (ISI). At an ISI of 1 s, depression is rapid and reaches a plateau at 36% of control. The depression at an ISI of 100 s is less pronounced, showing a gradual decay to 65% of control with the 10th EPSP. There are no significant differences in time course or magnitude of depression across a broad range of intermediate ISI (3, 10 and 30 s), although depression at these ISI is intermediate between the 1-100 s ISI. There is also a complex relationship between spike interval and the depression of the 2nd of 2 EPSP. Depression of the 2nd of EPSP or depression of a train of EPSP is not a monotonic function of spike interval. There may be a slight underlying facilitatory process with short spike intervals. The recovery of synaptic depression following a train of 10 stimuli is not constant; shorter spike intervals produce more rapid recovery. These data are inconsistent with a classical depletion model for synaptic depression and indicate that either a single complex function of time and ISI or multiple functions underlie synaptic depression and its recovery at the sensory neuron synapse.