Otmakhov N, Shirke A M, Malinow R
Department of Physiology and Biophysics, University of Iowa, Iowa City 52242.
Neuron. 1993 Jun;10(6):1101-11. doi: 10.1016/0896-6273(93)90058-y.
We have investigated the impact of stochastic transmission on the input-output relations of neurons in hippocampal slices. A synaptic input that fires a cell has a significant trial-to-trial variability in amplitude, reflecting the probabilistic release of transmitter. By measuring miniature excitatory postsynaptic currents, we estimate that synchronous release of a few vesicles can fire a CA1 cell. The firing threshold and variability can be physiologically modulated. Different cell types have distinct firing thresholds and variabilities. Long-term potentiation (LTP) decreases trial-to-trial variability. If after LTP, the stimulus is reduced to produce a threshold response, the variability returns to that observed before LTP. Thus, for a threshold input, the trial-to-trial variability is maintained with LTP. This may be important for the proper functioning of a plastic nervous system.
我们研究了随机传递对海马切片中神经元输入-输出关系的影响。激发细胞的突触输入在幅度上具有显著的逐次试验变异性，这反映了递质的概率性释放。通过测量微小兴奋性突触后电流，我们估计少数囊泡的同步释放就能激发一个CA1细胞。激发阈值和变异性可在生理上进行调节。不同细胞类型具有不同的激发阈值和变异性。长时程增强（LTP）可降低逐次试验变异性。如果在LTP之后，将刺激强度降低以产生阈值反应，变异性会恢复到LTP之前观察到的水平。因此，对于阈值输入，LTP可维持逐次试验变异性。这对于可塑性神经系统的正常功能可能很重要。
