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。感觉处理障碍是中枢神经系统疾病和衰老以及先天性疾病如精神分裂症和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。目前对嗅觉功能的观点认为，将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。在该奖项的过去资助期间完成的工作提供了证据，证明梨状皮质神经元的气味编码是高度动态的，并且似乎与该皮质的经验依赖性合成作用一致。此外，获得的证据表明，前梨状皮质神经系综编码气味的身份，而后梨状皮质系综编码气味的质量。新皮层感觉系统中的经验依赖性物体编码和感知严重依赖于内在的皮层内关联纤维。一个类似的，高度可塑性的内在关联系统存在于梨状皮质中，事实上，与前梨状皮质相比，后梨状皮质中的树突树占主导地位。本研究采用单单位、多单位和行为技术，探讨梨状皮质内纤维系统在气味编码和感知中的作用。目标1提出了参数化地检查如何需要平衡模式完成（在恒定刺激内的微小变化之间的泛化）和模式分离（相似气味的辨别）在梨状皮质中得到满足并转化为行为，目的2提出进一步研究经验对梨状皮质前部和后部的模式完成和分离的影响，目的3探讨气味体验诱导的皮层内连接可塑性及其在皮层整体形成和气味辨别中的作用。 皮质网络的信息处理对于正常的感官知觉、记忆和对环境的运动反应至关重要。了解信息是如何进入这些网络并由其进行分析的，将对我们解释和治疗这些基本认知功能障碍的能力产生根本性的影响。这个提议利用嗅觉系统相对简单的组织结构及其强大的可塑性来研究感觉经验如何改变皮层回路功能。

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 schizophrenia and 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 views of olfactory function suggest that re- assembly of these features into perceptual odor wholes is performed largely by circuits in the primary olfactory cortex. Work completed during the past funding period of this award provided evidence that odor encoding by piriform cortical neurons is highly dynamic, and appears to be consistent with the experience-dependent synthetic role proposed for this cortex. In addition, evidence was obtained suggesting that anterior piriform cortex neural ensembles encode odor identity, while posterior piriform cortical ensembles encode odor quality. Experience-dependent object encoding and perception in neocortical sensory systems is heavily dependent on intrinsic, intracortical association fibers. A similar, highly plastic intrinsic association system exists in the piriform cortex, and in fact dominates dendritic trees in posterior piriform compared to anterior. The present proposal examines the role of the piriform cortical intrinsic fiber system in odor encoding and perception using single-unit, multiple single-unit and behavioral techniques. Aim 1 proposes to parametrically examine how needs for a balance between pattern completion (generalization between slight variance within an otherwise constant stimulus) and pattern separation (discrimination of similar odors) are met in piriform cortex and translated to behavior, Aim 2 proposes to further examine the effects of experience on pattern completion and separation in anterior and posterior piriform cortex, and Aim 3 proposes to examine odor experience-induced plasticity of intrinsic cortical connections and their role of cortical ensemble formation and odor discrimination. Information processing by cortical networks is critical for normal sensory perception, memory, and motor responses to the environment. Understanding how information is entered into, and analyzed by these networks will have a fundamental impact on our ability to interpret and treat disorders of these basic cognitive functions. This proposal takes advantage of the relatively simple organization of the olfactory system and its robust plasticity to examine how sensory experience modifies cortical circuit function.