The timing between synaptic inputs has been proposed to play a role in the induction of plastic changes that enable neural circuits to store information. In the case of spike timing‐dependent plasticity (STDP), this relates to the interval between a synaptic input and a postsynaptic spike, thus providing a conceptual link to the Hebb learning rule. Experiments have documented STDP in many synapses and brain regions, and computational models have tested its utility in many neural network functions. However, questions remain about whether timing plays a role in plasticity during natural activity, and whether it can function in information storage. The present study used imaging with voltage sensitive dye to investigate the effectiveness of input timing in the plasticity of responses in the CA3 region of hippocampal slices. Plasticity was induced by sequential dual‐site stimulation at 10 ms intervals of either synaptic inputs and cell bodies (synaptic–somatic induction) or of two sets of synaptic inputs (synaptic–synaptic induction). Both protocols potentiated responses, with greater potentiation of responses to the first stimulation of the sequence than the second. Neither of these protocols induced depression. Synaptic–somatic stimulation was much more effective than synaptic–synaptic stimulation in evoking somatic action potentials, but both protocols potentiated responses equally well. This suggests that sequential dual‐site stimulation can potentiate equally well with very different degrees of somatic action potential firing. With synaptic–somatic induction, potentiation was focused at the sites of stimulation. In contrast, with synaptic–synaptic induction, the distribution of potentiation varied greatly. Changes in the spatial distribution of responses indicated that sequential dual‐site stimulation functions poorly in the storage of activity patterns. These results suggest that in the hippocampal CA3 region, timed sequential activation of two inputs is less effective than theta bursts, both in the induction of LTP and in the storage of information.

中文翻译：

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海马 CA3 区域的 Hebbian 和非 Hebbian 时间依赖性可塑性。

突触输入之间的时间安排在诱导塑性变化中发挥作用，使神经回路能够存储信息。在尖峰时间依赖性可塑性 (STDP) 的情况下，这与突触输入和突触后尖峰之间的间隔有关，因此提供了与 Hebb 学习规则的概念链接。实验已经在许多突触和大脑区域中记录了 STDP，并且计算模型已经测试了它在许多神经网络功能中的实用性。然而，关于时间是否在自然活动中的可塑性中起作用，以及它是否可以在信息存储中起作用，仍然存在疑问。本研究使用电压敏感染料成像来研究输入时间对海马切片 CA3 区域响应可塑性的有效性。可塑性是由突触输入和细胞体（突触 - 体细胞诱导）或两组突触输入（突触 - 突触诱导）以 10 ms 间隔的顺序双位点刺激诱导的。两种方案都加强了反应，对序列的第一次刺激的反应比第二次加强。这些方案均未引起抑郁。在唤起躯体动作电位方面，突触-体细胞刺激比突触-突触刺激更有效，但两种方案同样能很好地增强反应。这表明连续双位点刺激可以同样好地增强不同程度的躯体动作电位激发。通过突触-体细胞诱导，增强作用集中在刺激部位。相比之下，通过突触-突触诱导，增强的分布差异很大。反应空间分布的变化表明，连续双位点刺激在活动模式存储方面的作用很差。这些结果表明，在海马 CA3 区域，在 LTP 的诱导和信息存储方面，两个输入的定时顺序激活不如 theta 爆发有效。