Kitanishi Takuma, Matsuo Naoki
Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan, and Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Kyoto 606-8501, Japan.
Graduate School of Medicine, Osaka University, Osaka 565-0871, Japan, and Career-Path Promotion Unit for Young Life Scientists, Kyoto University, Kyoto 606-8501, Japan
J Neurosci. 2017 Jan 11;37(2):269-280. doi: 10.1523/JNEUROSCI.1360-16.2016.
The claustrum, a subcortical structure situated between the insular cortex and striatum, is reciprocally connected with almost all neocortical regions. Based on this connectivity, the claustrum has been postulated to integrate multisensory information and, in turn, coordinate widespread cortical activity. Although studies have identified how sensory information is mapped onto the claustrum, the function of individual topographically arranged claustro-cortical pathways has been little explored. Here, we investigated the organization and function of identified claustro-cortical pathways in mice using multiple anatomical and optogenetic techniques. Retrograde and anterograde tracing demonstrated that the density of anterior claustrum-to-cortical projection differs substantially depending on the target cortical areas. One of the major targets was the medial entorhinal cortex (MEC) and the MEC-projecting claustral neurons were largely segregated from the neurons projecting to primary cortices M1, S1, or V1. Exposure to a novel environment induced c-Fos expression in a substantial number of MEC-projecting claustral neurons and some M1/S1/V1-projecting claustral neurons. Optogenetic silencing of the MEC-projecting claustral neurons during contextual fear conditioning impaired later memory retrieval without affecting basal locomotor activity or anxiety-related behavior. These results suggest that the dense, anterior claustro-MEC pathway that is largely separated from other claustro-cortical pathways is activated by novel context and modulates the MEC function in contextual memory.
The claustrum is a poorly understood subcortical structure reciprocally connected with widespread neocortical regions. We investigated the organization and function of identified claustro-cortical projections in mice using pathway-specific approaches. Anatomical tracing showed that the density of anterior claustrum-to-cortical projection is dependent on the target cortical areas and that the medial entorhinal cortex (MEC) is one of the major projection targets. Novel context exposure activated multiple claustro-cortical pathways and a large fraction of the activated neurons projected to the MEC. Optogenetic silencing of the claustro-MEC pathway during contextual fear learning suppressed subsequent memory retrieval. These results suggest that the dense claustro-MEC pathway is activated by novel context and modulates MEC function in contextual memory.
屏状核是位于岛叶皮质和纹状体之间的一种皮质下结构，与几乎所有新皮质区域相互连接。基于这种连接性，有人推测屏状核整合多感官信息，进而协调广泛的皮质活动。尽管研究已经确定了感觉信息如何映射到屏状核上，但对各个按拓扑排列的屏状核 - 皮质通路的功能却鲜有探索。在这里，我们使用多种解剖学和光遗传学技术研究了小鼠中已确定的屏状核 - 皮质通路的组织和功能。逆行和顺行追踪表明，前屏状核到皮质的投射密度根据目标皮质区域的不同而有很大差异。主要目标之一是内嗅皮质内侧（MEC），投射到MEC的屏状核神经元在很大程度上与投射到初级皮质M1、S1或V1的神经元分隔开来。暴露于新环境会在大量投射到MEC的屏状核神经元以及一些投射到M1/S1/V1的屏状核神经元中诱导c-Fos表达。在情境恐惧条件反射期间对投射到MEC的屏状核神经元进行光遗传学沉默会损害后期的记忆提取，而不影响基础运动活动或焦虑相关行为。这些结果表明，与其他屏状核 - 皮质通路在很大程度上分离的密集的前屏状核 - MEC通路被新环境激活，并在情境记忆中调节MEC功能。
屏状核是一种人们了解较少的皮质下结构，与广泛的新皮质区域相互连接。我们使用通路特异性方法研究了小鼠中已确定的屏状核 - 皮质投射的组织和功能。解剖学追踪表明，前屏状核到皮质的投射密度取决于目标皮质区域，并且内嗅皮质内侧（MEC）是主要投射目标之一。新环境暴露激活了多条屏状核 - 皮质通路，并且大部分被激活的神经元投射到MEC。在情境恐惧学习期间对屏状核 - MEC通路进行光遗传学沉默会抑制随后的记忆提取。这些结果表明，密集的屏状核 - MEC通路被新环境激活，并在情境记忆中调节MEC功能。
