Associative encoding in posterior piriform cortex during odor discrimination and reversal learning
Associative encoding in posterior piriform cortex during odor discrimination and reversal learning
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DOI：
10.1093/cercor/bhl045
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发表时间：
2007-06-01
期刊：
影响因子：
3.7
通讯作者：
Schoenbaum, Geoffrey
中科院分区：
文献类型：
--
作者：
Calu, Donna J.;Roesch, Matthew R.;Schoenbaum, Geoffrey
最近的建议将梨状皮质概念为一种关联皮质，能够整合来自眶额皮质和基底外侧杏仁核（ABL）等高阶关联区域的传入嗅觉信息和下行输入。如果这是真的，梨状皮质的编码应该反映了这些区域在涉及嗅觉线索的联想学习中突出的联想特征。我们最近报道了大鼠前梨状皮质（APC）神经元在联想学习过程中对气味线索的反应表现出显著的可塑性。在这里，我们重复了这项研究，记录了梨状皮质后部（PPC）的神经元，这是一个接收ABL更强输入的梨状皮质区域。如果梨状皮质的联想编码是由ABL的输入驱动的，那么我们应该看到PPC神经元比APC神经元更具可塑性。与这一假设相一致，我们发现PPC神经元是高度关联的，并且在任务中气味-结果关联逆转后，PPC神经元似乎比APC中记录的神经元更有可能改变它们对气味线索的反应。此外，气味选择性PPC种群表现出明显不同的基于气味线索价的放电模式。这些结果表明，梨状皮质的联想编码以一种地形方式表现出来，反映了嗅球对前部区域气味感觉特征的更强和更具体的输入，以及ABL对后部区域气味意义的更强输入。
Recent proposals have conceptualized piriform cortex as an association cortex, capable of integrating incoming olfactory information with descending input from higher order associative regions such as orbitofrontal cortex and basolateral amygdala (ABL). If true, encoding in piriform cortex should reflect associative features prominent in these areas during associative learning involving olfactory cues. We recently reported that neurons in anterior piriform cortex (APC) in rats exhibited significant plasticity in their responses to odor cues during associative learning. Here, we have repeated this study, recording from neurons in posterior piriform cortex (PPC), a region of piriform cortex that receives much stronger input from ABL. If associative encoding in piriform cortex is driven by inputs from ABL, then we should see more plasticity in PPC neurons than we observed in APC. Consistent with this hypothesis, we found that PPC neurons were highly associative and appeared to be somewhat more likely than neurons recorded in APC to alter their responses to the odor cues after reversal of the odor-outcome associations in the task. Further, odor-selective PPC populations exhibited markedly different firing patterns based on the valence of the odor cue. These results suggest associative encoding in piriform cortex is represented in a topographical fashion, reflecting the stronger and more specific input from olfactory bulb concerning the sensory features of odors in anterior regions and stronger input from ABL concerning the meaning of odors in posterior regions.