Tobin William F, Wilson Rachel I, Lee Wei-Chung Allen
Department of Neurobiology, Harvard Medical School, Boston, United States.
Elife. 2017 May 22;6:e24838. doi: 10.7554/eLife.24838.
Neural network function can be shaped by varying the strength of synaptic connections. One way to achieve this is to vary connection structure. To investigate how structural variation among synaptic connections might affect neural computation, we examined primary afferent connections in the olfactory system. We used large-scale serial section electron microscopy to reconstruct all the olfactory receptor neuron (ORN) axons that target a left-right pair of glomeruli, as well as all the projection neurons (PNs) postsynaptic to these ORNs. We found three variations in ORN→PN connectivity. First, we found a systematic co-variation in synapse number and PN dendrite size, suggesting total synaptic conductance is tuned to postsynaptic excitability. Second, we discovered that PNs receive more synapses from ipsilateral than contralateral ORNs, providing a structural basis for odor lateralization behavior. Finally, we found evidence of imprecision in ORN→PN connections that can diminish network performance.
神经网络功能可通过改变突触连接强度来塑造。实现这一点的一种方法是改变连接结构。为了研究突触连接之间的结构变化如何影响神经计算，我们检查了嗅觉系统中的初级传入连接。我们使用大规模连续切片电子显微镜重建了所有靶向左右一对肾小球的嗅觉受体神经元（ORN）轴突，以及这些ORN突触后的所有投射神经元（PN）。我们发现ORN→PN连接存在三种变化。首先，我们发现突触数量和PN树突大小存在系统性的共同变化，这表明总突触电导是根据突触后兴奋性进行调节的。其次，我们发现PN从同侧ORN接收的突触比从对侧ORN接收的更多，这为气味侧向化行为提供了结构基础。最后，我们发现了ORN→PN连接不精确的证据，这种不精确会降低网络性能。
