Ensemble coding in olfactory cortex

摘要感觉信息的皮层加工在感觉辨别、物体识别和记忆中起着至关重要的作用。大脑皮层的感觉处理过程是高度动态的，过去的经验、当前的环境和期望塑造了人们如何每时每刻地感知世界。感觉加工障碍是中枢神经系统疾病和衰老以及精神分裂症和自闭症等先天性疾病引起的损伤的主要组成部分。在嗅觉感觉（梨状）皮层中，各种刺激特征通过传入和内在纤维的收敛和可塑性合成为感知整体，从而使熟悉的气味物体被记忆。priform皮质的内在关联纤维系统是广泛的，基于解剖学数据和新的生理数据支持的R21对co-PI的支持，它在形成皮层对气味刺激的集合活动中起作用。因此，我们的数据表明，气味唤起整个前梨状皮质（aPCX）的分布式单元集合活动，集合的各个组成部分贡献了多种气味表征。在目前的提议中，我们扩展了r21支持的研究，我们建议在麻醉和清醒的大鼠中使用多电极阵列和配对单单元记录来解决三个先前未经验证的关于嗅觉皮层集合功能的假设。目的1将验证如下假设：由于pPCX具有更广泛的内在兴奋性关联纤维系统，后端PCX （pPCX）的细胞整体成员大小和配对单单元相关活动的概率将大于aPCX。目的2将检验神经调节剂ACh和NE对PCX的操纵这一假设，它选择性地影响内在纤维突触的功效，将调节组合成员的大小、气味特异性和配对单单元相关活动的概率。最后，Aim 3将验证行为状态可能通过胆碱能或去甲肾上腺素能机制调节细胞对的集合大小、气味特异性和相关活动概率的假设。总之，这些目标将开始探索皮层集合如何将周围电路编码的无数气味特征合并为气味物体，以及注意力和唤醒如何调节气味辨别。信息的皮质加工在感觉知觉、记忆、运动和认知中起着至关重要的作用。因此，了解大脑皮层内的回路如何处理信息对于理解和治疗信息处理障碍非常重要。本研究利用一个相对简单的皮质回路（梨状皮质）执行相对复杂的信息处理任务（气味物体识别）来探索神经元群如何作为一个整体一起工作来解释感觉输入。

DESCRIPTION (provided by applicant): 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 multiple 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 cholinergic 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 attention and arousal may modulate odor discrimination. PUBLIC HEALTH RELEVANCE 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.