Hsia A Y, Malenka R C, Nicoll R A
Neuroscience Graduate Program, University of California, San Francisco, San Francisco, California 94143, USA.
J Neurophysiol. 1998 Apr;79(4):2013-24. doi: 10.1152/jn.1998.79.4.2013.
Assessing the development of local circuitry in the hippocampus has relied primarily on anatomic studies. Here we take a physiological approach, to directly evaluate the means by which the mature state of connectivity between CA3 and CA1 hippocampal pyramidal cells is established. Using a technique of comparing miniature excitatory postsynaptic currents (mEPSCs) to EPSCs in response to spontaneously occurring action potentials in CA3 cells, we found that from neonatal to adult ages, functional synapses are created and serve to increase the degree of connectivity between CA3-CA1 cell pairs. Neither the probability of release nor mean quantal size was found to change significantly with age. However, the variability of quantal events decreases substantially as synapses mature. Thus in the hippocampus the developmental strategy for enhancing excitatory synaptic transmission does not appear to involve an increase in the efficacy at individual synapses, but rather an increase in the connectivity between cell pairs.
评估海马体中局部神经回路的发育主要依赖于解剖学研究。在此，我们采用生理学方法，直接评估建立海马体CA3和CA1锥体细胞之间成熟连接状态的方式。通过比较微型兴奋性突触后电流（mEPSCs）与CA3细胞中自发动作电位引发的兴奋性突触后电流（EPSCs）的技术，我们发现从新生期到成年期，功能性突触不断形成，并有助于增加CA3-CA1细胞对之间的连接程度。释放概率和平均量子大小均未发现随年龄有显著变化。然而，随着突触成熟，量子事件的变异性大幅降低。因此，在海马体中，增强兴奋性突触传递的发育策略似乎并不涉及单个突触效能的增加，而是细胞对之间连接性的增加。
