Qualcomm Research, San Diego, CA 92121, USA.
J Neurophysiol. 2012 Jul;108(2):551-66. doi: 10.1152/jn.01150.2011. Epub 2012 Apr 11.
Studies of spike timing-dependent plasticity (STDP) have revealed that long-term changes in the strength of a synapse may be modulated substantially by temporal relationships between multiple presynaptic and postsynaptic spikes. Whereas long-term potentiation (LTP) and long-term depression (LTD) of synaptic strength have been modeled as distinct or separate functional mechanisms, here, we propose a new shared resource model. A functional consequence of our model is fast, stable, and diverse unsupervised learning of temporal multispike patterns with a biologically consistent spiking neural network. Due to interdependencies between LTP and LTD, dendritic delays, and proactive homeostatic aspects of the model, neurons are equipped to learn to decode temporally coded information within spike bursts. Moreover, neurons learn spike timing with few exposures in substantial noise and jitter. Surprisingly, despite having only one parameter, the model also accurately predicts in vitro observations of STDP in more complex multispike trains, as well as rate-dependent effects. We discuss candidate commonalities in natural long-term plasticity mechanisms.
研究尖峰时间依赖可塑性 (STDP) 表明,突触强度的长期变化可能会受到多个前突触和后突触尖峰之间的时间关系的极大调节。虽然突触强度的长时程增强 (LTP) 和长时程抑制 (LTD) 已被建模为不同或独立的功能机制,但在这里,我们提出了一个新的共享资源模型。我们模型的一个功能后果是,使用具有生物学一致性的放电神经网络快速、稳定和多样化地对多尖峰模式进行无监督学习。由于 LTP 和 LTD、树突延迟以及模型的主动稳态方面之间的相互依赖关系,神经元能够学会解码尖峰爆发中的时间编码信息。此外,神经元在大量噪声和抖动中只需几次暴露就能学习到尖峰时间。令人惊讶的是,尽管该模型只有一个参数,但它还可以准确预测更复杂的多尖峰训练中体外观察到的 STDP 以及与率相关的效应。我们讨论了自然长时程可塑性机制中的候选共性。