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首页> 外文期刊>The European Journal of Neuroscience >Modulation of synaptic transmission in neocortex by network activities.
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Modulation of synaptic transmission in neocortex by network activities.

机译：网络活动对新皮层突触传递的调节。

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Neocortical neurons integrate inputs from thousands of presynaptic neurons that fire in vivo with frequencies that can reach 20 Hz. An important issue in understanding cortical integration is to determine the actual impact of presynaptic firing on postsynaptic neuron in the context of an active network. We used dual intracellular recordings from synaptically connected neurons or microstimulation to study the properties of spontaneous and evoked single-axon excitatory postsynaptic potentials (EPSPs) in vivo, in barbiturate or ketamine-xylazine anaesthetized cats. We found that active states of the cortical network were associated with higher variability and decrease in amplitude and duration of the EPSPs owing to a shunting effect. Moreover, the number of apparent failures markedly increased during active states as compared with silent states. Single-axon EPSPs in vivo showed mainly paired-pulse facilitation, and the paired-pulse ratio increased during active states as compare to silent states, suggesting a decrease in release probability during active states. Raising extracellular Ca(2+) concentration to 2.5-3.0 mm by reverse microdialysis reduced the number of apparent failures and significantly increased the mean amplitude of individual synaptic potentials. Quantitative analysis of spontaneous synaptic activity suggested that the proportion of presynaptic activity that impact at the soma of a cortical neuron in vivo was low because of a high failure rate, a shunting effect and probably dendritic filtering. We conclude that during active states of cortical network, the efficacy of synaptic transmission in individual synapses is low, thus safe transmission of information requires synchronized activity of a large population of presynaptic neurons.
机译：新皮层神经元整合了成千上万的突触前神经元的输入，这些神经元在体内激发的频率可达20 Hz。理解皮质整合的一个重要问题是在活动网络的背景下确定突触前放电对突触后神经元的实际影响。我们使用了来自突触连接的神经元或微刺激的双重胞内记录，以研究巴比妥酸盐或氯胺酮-甲苯噻嗪麻醉的猫体内自发和诱发的单轴突兴奋性突触后突触电位（EPSP）的特性。我们发现，由于分流效应，皮层网络的活动状态与更高的可变性以及EPSP的幅度和持续时间的减少相关。此外，与静默状态相比，活动状态期间的明显故障数明显增加。体内单轴突EPSPs主要表现为成对脉冲促进，并且与沉默状态相比，在成活状态下成对脉冲比率增加，这表明在成活状态下释放概率降低。通过反向微透析将细胞外Ca（2+）浓度提高到2.5-3.0 mm，减少了明显的失败次数，并显着增加了单个突触电位的平均幅度。对自发突触活动的定量分析表明，由于高失败率，分流效应和可能的树突过滤，影响体内皮层神经元躯体的突触前活动的比例较低。我们得出的结论是，在皮层网络活动状态期间，突触传递在单个突触中的功效很低，因此，信息的安全传递需要大量突触前神经元的同步活动。

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