Department of Neuroscience, Physiology and Pharmacology, University College London, 21 University St., London WC1E 6DE, UK.
Department of Biomedical Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ, UK.
Cell Rep. 2018 Jan 16;22(3):576-584. doi: 10.1016/j.celrep.2017.12.065.
Persistent synapses are thought to underpin the storage of sensory experience, yet little is known about their structural plasticity in vivo. We investigated how persistent presynaptic structures respond to the loss of primary sensory input. Using in vivo two-photon (2P) imaging, we measured fluctuations in the size of excitatory axonal boutons in L2/3 of adult mouse visual cortex after monocular enucleation. The average size of boutons did not change after deprivation, but the range of bouton sizes was reduced. Large boutons decreased, and small boutons increased. Reduced bouton variance was accompanied by a reduced range of correlated calcium-mediated neural activity in L2/3 of awake animals. Network simulations predicted that size-dependent plasticity may promote conditions of greater bidirectional plasticity. These predictions were supported by electrophysiological measures of short- and long-term plasticity. We propose size-dependent dynamics facilitate cortical reorganization by maximizing the potential for bidirectional plasticity.
持续的突触被认为是支撑感觉体验存储的基础，但对于它们在体内的结构可塑性知之甚少。我们研究了持续的突触前结构如何对主要感觉输入的丧失做出反应。我们使用体内双光子（2P）成像技术，测量了成年小鼠视觉皮层 L2/3 中兴奋性轴突末梢在单眼切除后的大小波动。剥夺后，末梢的平均大小没有变化，但末梢大小的范围减小了。大末梢减少，小末梢增加。末梢方差的降低伴随着清醒动物 L2/3 中钙介导的神经活动相关性的范围减小。网络模拟预测，大小依赖性可塑性可能促进双向可塑性更大的条件。这些预测得到了短期和长期可塑性的电生理测量的支持。我们提出，大小依赖性动力学通过最大化双向可塑性的潜力来促进皮层重组。
