Illig Kurt R
Department of Psychology, University of Virginia, Charlottesville, VA 22904, USA.
J Comp Neurol. 2005 Jul 25;488(2):224-31. doi: 10.1002/cne.20595.
The orbitofrontal cortex (OFC) has been characterized as a higher-order, multimodal sensory cortex. Evidence from electrophysiological and behavioral studies in the rat has suggested that OFC plays a role in modulating olfactory guided behavior, and a significant projection to OFC arises from piriform cortex, the traditional primary olfactory cortex. To discern how OFC interacts with primary olfactory structures, the anterograde tracer Phaseolus vulgaris leucoagglutinin was injected into orbitofrontal cortical areas in adult male rats. Labeled fibers were found in the piriform cortex and olfactory bulb on the side ipsilateral to the injection. Notably, the projection to piriform cortex was predominantly from ventrolateral orbital cortex, and was not uniform; rostrally, the projection to the ventral portion of the anterior piriform cortex (APC) was substantial, while the dorsal APC was virtually free of labeled fibers. Labeled fibers were found in both the dorsal and ventral portions in more caudal regions of APC. Most labeled fibers were found in layer III, although a substantial number of fibers were observed in layers Ib and II. Labeled fibers in posterior piriform cortex also were seen after injection into orbitofrontal areas. Taken together with previous reports, these findings suggest that piriform cortex includes multiple subdivisions, which may perform separate, parallel functions in olfactory information processing. Further, these results suggest that the OFC, in addition to its putative role in encoding information about the significance of olfactory stimuli, may play a role in modulating odor response properties of neurons in piriform cortex.
眶额皮质（OFC）已被描述为一种高阶多模态感觉皮质。大鼠的电生理和行为学研究证据表明，OFC在调节嗅觉引导行为中发挥作用，并且梨状皮质（传统的初级嗅觉皮质）向OFC发出大量投射。为了探究OFC如何与初级嗅觉结构相互作用，将顺行示踪剂菜豆白细胞凝集素注入成年雄性大鼠的眶额皮质区域。在注射同侧的梨状皮质和嗅球中发现了标记纤维。值得注意的是，向梨状皮质的投射主要来自腹外侧眶皮质，且并不均匀；在吻侧，向前梨状皮质（APC）腹侧部分的投射大量存在，而背侧APC几乎没有标记纤维。在APC更靠尾侧区域的背侧和腹侧部分均发现了标记纤维。大多数标记纤维位于III层，尽管在Ib层和II层也观察到大量纤维。向眶额区域注射后，在梨状后皮质也可见标记纤维。结合先前的报道，这些发现表明梨状皮质包括多个亚区，它们可能在嗅觉信息处理中执行独立、并行的功能。此外，这些结果表明，OFC除了在编码嗅觉刺激重要性信息方面可能发挥的作用外，还可能在调节梨状皮质中神经元的气味反应特性方面发挥作用。
