Long-Term Plasticity in the Regulation of Olfactory Bulb Activity by Centrifugal Fibers from Piriform Cortex
Long-Term Plasticity in the Regulation of Olfactory Bulb Activity by Centrifugal Fibers from Piriform Cortex
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DOI：
10.1523/jneurosci.1314-14.2014
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发表时间：
2014-07-16
影响因子：
5.3
通讯作者：
Stripling, Jeffrey S.
中科院分区：
文献类型：
--
作者：
Cauthron, Joy L.;Stripling, Jeffrey S.
嗅球颗粒细胞通过两条主要途径被突触激活。二尖瓣/簇状（M/T）细胞在颗粒细胞上形成树突状突触，颗粒细胞可被外侧嗅束（LOT）的逆向刺激激活。起源于梨状皮质（PC）中的联合纤维（AF）系统的离心纤维在颗粒细胞层（GCL）内的颗粒细胞上形成轴-树突触，其可以被PC中的AF轴突的顺向刺激激活。我们探讨了AF通路的功能可塑性，通过记录来自单个M/T细胞和假定的颗粒细胞在雄性Long-Evans大鼠乌拉坦麻醉下，同时测试其响应LOT和AF刺激的细胞外。推测的颗粒细胞驱动突触的LOT刺激（L型细胞）集中在浅的一半的GCL和激活在短的潜伏期，而那些驱动突触的AF刺激（A型细胞）集中在深的一半的GCL和激活在较长的潜伏期。A型细胞很容易被检测到，只有在动物中，AF输入到GCL先前已被反复高频刺激增强。在乌拉坦下给予的额外一轮高频刺激引起AF测试刺激在A型细胞中诱发的动作电位数量立即增加，并且伴随着M/T细胞抑制的增加。这些结果强调了PC调节OB活性在嗅觉处理中所起作用的重要性，并记录了重复高频AF激活对该调节的长期增强作用。
Olfactory bulb granule cells are activated synaptically via two main pathways. Mitral/tufted (M/T) cells form dendrodendritic synapses on granule cells that can be activated by antidromic stimulation of the lateral olfactory tract (LOT). Centrifugal fibers originating from the association fiber (AF) system in piriform cortex (PC) make axodendritic synapses on granule cells within the granule cell layer (GCL) that can be activated by orthodromic stimulation of AF axons in the PC. We explored functional plasticity in the AF pathway by recording extracellularly from individual M/T cells and presumed granule cells in male Long-Evans rats under urethane anesthesia while testing their response to LOT and AF stimulation. Presumed granule cells driven synaptically by LOT stimulation (type L cells) were concentrated in the superficial half of the GCL and were activated at short latencies, whereas those driven synaptically by AF stimulation (type A cells) were concentrated in the deep half of the GCL and were activated at longer latencies. Type A cells were readily detected only in animals in which the AF input to the GCL had been previously potentiated by repeated high-frequency stimulation. An additional bout of high-frequency stimulation administered under urethane caused an immediate increase in the number of action potentials evoked in type A cells by AF test stimulation and a concomitant increase in inhibition of M/T cells. These results underscore the importance of the role played in olfactory processing by PC regulation of OB activity and document the long-lasting potentiation of that regulation by repeated high-frequency AF activation.