Distributed synaptic modification in neural networks induced by patterned stimulation
Distributed synaptic modification in neural networks induced by patterned stimulation
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作者：
Bi, GQ;Poo, MM
突触效能或连通性的活动依赖性变化对神经系统的发育(1)、信号处理(2)以及学习和记忆功能（3-6）至关重要。突触前和突触后神经元的重复相关尖峰可以诱导突触强度的持续增加或减少，这取决于突触前和突触后兴奋的时间（7-13）。先前对这种突触修饰的研究主要集中在受刺激神经元产生的突触上。在这里，我们研究了在培养的海马神经元网络中，局部刺激是否以及如何改变远离受刺激神经元的突触。我们发现，短时间内对单个神经元的重复成对脉冲刺激会导致特定多突触通路以一种取决于脉冲间隔的方式持续增强或减弱。这些变化可以通过突触前和突触后在远端突触位点的相关兴奋来解释，这些突触前和突触后的兴奋是由不同通路上的不同传递延迟造成的。因此，通过这种“延迟线”机制，编码在单个尖峰时间中的时间信息（14-17）可以转换为并存储为神经网络中持续突触修饰的空间分布模式。
Activity-dependent changes in synaptic efficacy or connectivity are critical for the development(1), signal processing(2) and learning and memory functions(3-6) of the nervous system. Repetitive correlated spiking of pre- and postsynaptic neurons can induce a persistent increase or decrease in synaptic strength, depending on the timing of the pre- and postsynaptic excitation(7-13). Previous studies on such synaptic modifications have focused on synapses made by the stimulated neuron. Here we examine, in networks of cultured hippocampal neurons, whether and how localized stimulation can modify synapses that are remote from the stimulated neuron. We found that repetitive paired-pulse stimulation of a single neuron for brief periods induces persistent strengthening or weakening of specific polysynaptic pathways in a manner that depends on the interpulse interval. These changes can be accounted for by correlated pre- and postsynaptic excitation at distant synaptic sites, resulting from different transmission delays along separate pathways. Thus, through such a 'delay-line' mechanism, temporal information coded in the timing of individual spikes(14-17) can be converted into and stored as spatially distributed patterns of persistent synaptic modifications in a neural network.