Cortical processing of olfactory stimuli

描述(申请人提供)：感觉信息的皮质处理在感觉辨别、物体识别和记忆中起着关键作用。大脑皮层的感觉处理已被证明是高度动态的，过去的经验、当前的背景和预期塑造了人们在一瞬间如何感知世界。感觉加工障碍是中枢神经系统疾病和衰老以及自闭症等先天性疾病引起的损害的主要组成部分。在嗅觉系统中，气味分子和混合物的特征被认为是由受体膜上的一大类嗅觉受体蛋白提取的，并通过与嗅球的突触处理进一步定义。目前的嗅觉功能理论表明，将这些特征重新组装成感知气味的整体，主要是通过初级嗅觉皮质的回路完成的。在该奖项过去的资助期内完成的工作提供了证据，表明嗅觉皮质神经元的感受野(RF)是高度动态的，似乎与为该皮质提出的合成作用一致。也就是说，单个梨状皮质神经元对分子上相似的气味表现出高度的辨别能力，而它们的初级传入细胞、二尖瓣/簇状细胞似乎表达了检测RF的特征。然而，鉴于动物可以区分的气味和气味混合物的广泛范围，皮质合成编码不太可能是天生的硬连接，而是反映了一种依赖经验的知觉学习过程，允许合成新的共生特征。本研究采用多学科的方法，寻求梨状皮质合成编码的进一步证据(目标1)，并开始探索知觉学习和合成皮质射频形成的必要条件和机制(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).