Hwang Eunkyu, Willis Bailey S, Burwell Rebecca D
Department of Cognitive, Linguistic, and Psychological Sciences, Brown University, Providence, RI 02912, USA.
Department of Molecular Pharmacology, Physiology, and Biotechnology, Brown University, Providence, RI 02912, USA.
Behav Brain Res. 2018 Nov 15;354:8-21. doi: 10.1016/j.bbr.2017.07.032. Epub 2017 Jul 29.
Knowing how prefrontal regions interact with medial temporal lobe structures is important for understanding memory and cognition. Using anterograde and retrograde tract tracing methods in the rat, we report a detailed study of the perirhinal (PER) and postrhinal (POR) connections with the lateral, ventrolateral, and medial orbitofrontal cortices (ORBl, ORBvl, ORBm), infralimbic and prelimbic cortices (IL, PL), ventral and dorsal anterior cingulate cortices (ACAv, ACAd), and secondary motor cortex (MOs). Our analyses included the topography and laminar patterns of these connections. The PER and POR showed reciprocal connectivity with all prefrontal regions examined, but the patterns of connections differed. In general, PER areas 36 and 35 showed patterns of connectivity that were more similar to each other than to those of the POR. Analysis of anterograde tracers showed that PER areas 36 and 35 provide the strongest projections to prefrontal regions. The heaviest fiber labeling was in IL and PL, closely followed by orbital regions. Fiber labeling arising from injections in POR was weaker overall. The strongest POR efferents targeted MOs, ACAv, and ORBvl. For return projections, analysis of retrograde tracers showed that PER areas 36 and 35 receive strong inputs from orbitofrontal and medial prefrontal regions. Interestingly, PER also received substantial inputs from MOs and ACAd. The POR receives a very strong input from MOs, followed by ACAd, and ORBvl. Based on comparison of our findings with those obtained in monkeys, we argue that the rodent ACAd and MOs may be a functional homolog of the primate dorsolateral prefrontal cortex.
了解前额叶区域如何与内侧颞叶结构相互作用对于理解记忆和认知至关重要。我们使用大鼠的顺行和逆行示踪方法，详细研究了内嗅区（PER）和外嗅区（POR）与外侧、腹外侧和内侧眶额皮质（ORBl、ORBvl、ORBm）、内嗅下皮质和前扣带前皮质（IL、PL）、腹侧和背侧前扣带皮质（ACAv、ACAd）以及次级运动皮质（MOs）之间的连接。我们的分析包括这些连接的拓扑结构和分层模式。PER和POR与所有检查的前额叶区域都显示出相互连接，但连接模式不同。一般来说，PER的36区和35区之间的连接模式彼此之间比与POR的更相似。顺行示踪剂分析表明，PER的36区和35区向前额叶区域提供最强的投射。纤维标记最密集的是在IL和PL，其次是眶区。总体而言，POR注射产生的纤维标记较弱。POR最强的传出纤维靶向MOs、ACAv和ORBvl。对于返回投射，逆行示踪剂分析表明，PER的36区和35区从眶额和内侧前额叶区域接收强烈输入。有趣的是，PER还从MOs和ACAd接收大量输入。POR从MOs接收非常强烈的输入，其次是ACAd和ORBvl。基于将我们的研究结果与在猴子中获得的结果进行比较，我们认为啮齿动物的ACAd和MOs可能是灵长类动物背外侧前额叶皮质的功能同源物。
