Cortical processing of olfactory stimuli

描述（由申请人提供）：感觉信息的皮层处理在感觉辨别、物体识别和记忆中起着关键作用。大脑皮层的感觉处理被证明是高度动态的，过去的经验，当前的背景和期望塑造了世界是如何被感知的。感觉处理障碍构成由CNS疾病和衰老以及先天性障碍如自闭症引起的损伤的主要组成部分。在嗅觉系统中，气味分子和混合物的特征被认为是由受体片上的嗅觉受体蛋白大家族提取的，并通过与嗅球的突触加工进一步定义。目前的嗅觉功能理论表明，这些特征重新组装成感知气味的整体主要是由初级嗅觉皮层中的回路完成的。在过去的资助期内完成的工作提供的证据表明，嗅觉皮层神经元的感受野（RF）是高度动态的，似乎是一致的，为这个皮层提出的合成作用。也就是说，单个梨状皮质神经元表现出高度的歧视分子相似的气味，而他们的初级传入，二尖瓣/簇状细胞似乎表达功能检测RF的。然而，考虑到动物可以区分的气味和气味混合物的范围很广，皮质合成编码不太可能是由于先天的硬接线，而是反映了一种依赖于经验的感知学习过程，允许合成新的共同出现的特征。使用多学科的方法，本建议寻求进一步的证据，合成编码梨状皮质（目标1），并开始探索必要的条件，和机制，知觉学习和合成皮质RF的形成（目标2和3）。

DESCRIPTION (provided by applicant): Cortical processing of sensory information plays a critical role in sensory discrimination, object recognition and memory. Cortical sensory processing has been shown to be highly dynamic, with past experience, current context and expectations shaping how the world is perceived on a moment by moment basis. Disorders of sensory processing constitute a major component of impairments induced by CNS disease and aging as well as congenital disorders such as autism. In the olfactory system, features of odorant molecules and mixtures are believed to be extracted by a large family of olfactory receptor proteins at the receptor sheet, and further defined by synaptic processing with the olfactory bulb. Current theories of olfactory function suggest that re-assembly of these features into perceptual odorant wholes is performed largely by circuits in the primary olfactory cortex. Work completed during the past funding period of this award provided evidence that receptive fields (RF's) of olfactory cortical neurons were highly dynamic, and appeared to be consistent with the synthetic role proposed for this cortex. Namely, single piriform cortex neurons showed a high degree of discrimination of molecularly similar odorants, whereas their primary afferent, mitral/tufted cells appeared to express feature detecting RF's. However, given the broad range of odorants and odorant mixtures that animals can discriminate, it is unlikely that cortical synthetic coding is due to innate hard-wiring, but rather reflects an experience-dependent, perceptual learning process that allows synthesis of novel co-occurring features. Using a multidisciplinary approach, the present proposal seeks further evidence of synthetic coding in the piriform cortex (Aim 1), and begins to explore the necessary conditions for, and mechanisms of, perceptual learning and formation of synthetic cortical RF's (Aims 2 & 3).