Ensemble coding in olfactory cortex

摘要 感觉信息的皮层处理在感觉辨别中起着关键作用， 物体识别和记忆。皮质感觉处理已经被证明是 高度动态，过去的经验，当前的背景和期望塑造了 世界是以每时每刻为基础的。感觉处理障碍 构成由CNS疾病和衰老引起的损伤的主要组成部分， 以及精神分裂症和自闭症等先天性疾病。在嗅觉上 （梨状）皮层不同的刺激特征被合成为知觉整体 通过传入和内在纤维的会聚和可塑性， 要记住的对象。灵长类皮质中的内在联合纤维系统是 广泛的，并基于解剖数据和新的生理数据的支持， R21对co-PI的作用，在响应于以下的形成皮质整体活动中起作用： 气味刺激因此，我们的数据表明，气味唤起分布式单位 整个梨状前皮质（aPCX）的整体活动，具有单个组件 对多重气味表征的贡献。本 该提案扩展了R21支持的研究，我们建议解决三个问题 以前未经检验的假设，关于皮质整体功能的嗅觉使用 多电极阵列和成对的单单位记录在麻醉和清醒大鼠。 目标1将测试假设，即细胞系综成员的大小和概率， 配对单个单位的相关活动在后PCX（pPCX）中将大于 在aPCX中，由于pPCX中更广泛的内在兴奋性联合纤维系统。 目的2将检验神经调质ACh和NE的操纵以调节神经元的兴奋性的假设。 PCX选择性地影响内在纤维突触效能， 成员大小，气味特异性和相关活动的概率， 单人单位最后，目标3将检验行为状态将调节 系综大小、气味特异性和细胞对中相关活性的概率， 可能通过胆碱能或去甲肾上腺素能机制。总之，这些目标将 开始探索皮层集合体如何融合由编码的无数气味特征， 周围回路转化为有气味的物体，以及注意力和唤醒如何调节 气味辨别叙事 大脑皮层对信息的处理在感官知觉、记忆、 运动和认知。因此，了解大脑皮层内的电路如何处理 信息对于理解和治疗信息障碍非常重要 处理.这个提议利用了一个相对简单的皮层回路（ 梨状皮质）执行相对复杂的信息处理任务（气味对象 辨别）来探索神经元组如何作为一个整体一起工作， 解读感官输入

ABSTRACT 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 sensory (piriform) cortex diverse stimulus features are synthesized into perceptual wholes through afferent and intrinsic fiber convergence and plasticity, allowing familiar odor objects to be remembered. The intrinsic, association fiber system in priform cortex is extensive, and based on anatomical data and new physiological data supported by an R21 to the co-PI's, plays a role in shaping cortical ensemble activity in response to odorant stimuli. Thus, our data demonstrate that odorants evoke distributed unit ensemble activity throughout anterior piriform cortex (aPCX), with individual components of the ensemble contributing to mulitple odorant representations. In the present proposal, which extends the R21-supported research, we propose to address three previously untested hypotheses regarding cortical ensemble function in olfaction using multi-electrode array and paired single-unit recording in anesthetized and awake rats. Aim 1 will test the hypothesis that cell ensemble membership size and the probability of correlated activity in paired single-units will be greater in the posterior PCX (pPCX) than in aPCX due to the more extensive intrinsic excitatory association fiber system in pPCX. Aim 2 will test the hypothesis that manipulations of the neuromodulators ACh and NE to PCX, which selectively affect intrinsic fiber synaptic efficacy, will modulate ensemble membership size, odorant specificity and probability of correlated activity in paired single-units. Finally, Aim 3 will test the hypothesis that behavioral state will modulate ensemble size, odorant specificity and probability of correlated activity in cell pairs, potentially via a cholinergc or noradrenergic mechanism. Together, these aims will begin to explore how cortical ensembles merge the myriad odorant features encoded by peripheral circuits into odorant objects, and how attentiona and arousal may modulate odor discrimination. NARRATIVE Cortical processing of information plays a critical role in sensory perception, memory, movement and cognition. Thus, understanding how circuits within the cortex process information is important for understanding and treating disorders of information processing. This proposal takes advantage of a relatively simple cortical circuit (the piriform cortex) performing relatively complex information processing tasks (odor object discrimination) to explore how groups of neurons work together as an ensemble to interpret sensory input.