Ultrastructural organization of medial prefrontal inputs to the rhinal cortices
Ultrastructural organization of medial prefrontal inputs to the rhinal cortices
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DOI：
10.1111/j.1460-9568.2006.04894.x
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发表时间：
2006-07-01
影响因子：
3.4
通讯作者：
Pare, Denis
中科院分区：
文献类型：
--
作者：
Apergis-Schoute, John;Pinto, Aline;Pare, Denis
越来越多的证据表明，内侧前额叶皮层（mPFC）在大脑依赖记忆的形成、提取和长期储存中起着关键作用。与此相一致的是，有直接的海马投射到mPFC。此外，前额叶皮层还向嗅周和内嗅皮质发出强有力的投射，这两个相互关联的皮质区域将信息输入和输出海马体。然而，后一个预测的意义仍然不清楚，因为没有数据可用于mPFC轴突的鼻腔靶点。在本研究中，使用顺行追踪与菜豆白细胞凝集素和包埋前γ-氨基丁酸（GABA）的免疫细胞化学在豚鼠相结合的这个问题进行了研究。在mPFC中注射菜豆白细胞凝集素后，在嗅周（主要是浅层）和外侧内嗅（主要是深层）皮质中观察到顺行标记的轴突。在电子显微镜下，顺向标记的mPFC轴突终末与鼻周神经元和内嗅神经元的突触连接几乎相同。在这两个鼻腔领域，mPFC轴突终末只形成不对称的突触，通常与GABA免疫阴性的棘（约70%），但偶尔与树突状轮廓（约30%），其中一半是GABA免疫阳性。根据早期的观察，这些研究结果表明，mPFC输入发挥主要的兴奋性作用，在鼻腔皮质，preadministered上的主要神经元。因此，这些结果表明，mPFC可能会影响海马依赖的记忆，通过增强冲动交通进出海马在鼻腔皮质的水平。
Accumulating evidence suggests that the medial prefrontal cortex (mPFC) plays a critical role in the formation, retrieval and long-term storage of hippocampal-dependent memories. Consistent with this, there are direct hippocampal projections to the mPFC. Moreover, the mPFC sends robust projections to the perirhinal and entorhinal cortices, two interconnected cortical fields that funnel information into and out of the hippocampus. However, the significance of the latter projection remains unclear because no data are available regarding the rhinal targets of mPFC axons. This question was examined in the present study using a combination of anterograde tracing with Phaseolus vulgaris leucoagglutinin and pre-embedding gamma-aminobutyric acid (GABA) immunocytochemistry in guinea pigs. Following Phaseolus vulgaris leucoagglutinin injections in the mPFC, anterogradely labeled axons were seen in the perirhinal (mainly superficial layers) and lateral entorhinal (mainly deep layers) cortices. In the electron microscope, the synaptic articulation of anterogradely labeled mPFC axon terminals with perirhinal and entorhinal neurons was found to be nearly identical. In these two rhinal fields, mPFC axon terminals only formed asymmetric synapses, typically with GABA-immunonegative spines (approximate to 70%) but occasionally with dendritic profiles (approximate to 30%), half of which were GABA immunopositive. In the light of earlier observations, these findings indicate that mPFC inputs exert mainly excitatory effects in the rhinal cortices, prevalently on principal neurons. Thus, these results suggest that the mPFC may affect hippocampal-dependent memories by enhancing impulse traffic into and out of the hippocampus at the level of the rhinal cortices.