Ensemble coding in olfactory cortex

描述(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精神分裂症和自闭症等先天性疾病引起的损害的主要组成部分。在嗅觉(梨状)皮层，通过传入和固有的纤维汇聚和可塑性，不同的刺激特征被合成为感知整体，使人们能够记住熟悉的气味对象。初级皮质内固有的联合纤维系统是广泛的，基于解剖学数据和新的生理数据，在R21到co-PI‘s的支持下，在形成皮层对气味刺激的整体活动中起着作用。因此，我们的数据表明，气味唤起分布在梨状皮质前(APCX)的单位集合活动，该集合中的单个成分对多种气味表征起作用。在本提案中，扩展了R21支持的研究，我们建议使用多电极阵列和成对的单单位记录在麻醉和清醒的大鼠中解决关于嗅觉中的皮质整体功能的三个先前未被测试的假设。目的1验证一种假说，即后PCX(PPCX)内存在更广泛的固有兴奋性联结纤维系统，因此后PCX(PPCX)中细胞系综成员的大小和相关活动的概率将大于aPCX。目的2将验证神经调节剂ACh和NE对PCX选择性地影响固有纤维突触有效性的假设，即操纵ACh和NE到PCX将调节配对单个单位的整体成员大小、气味专一性和相关活动的概率。最后，目标3将测试这一假设，即行为状态将潜在地通过胆碱能或去甲肾上腺素能机制调节细胞对中整体大小、气味特异性和相关活动的概率。总之，这些目标将开始探索皮质集合如何将由外围电路编码的无数气味特征合并到气味对象中，以及注意力和唤醒如何调节气味识别。与公共健康相关的皮层信息处理在感觉知觉、记忆、运动和认知中起着关键作用。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。这项提议利用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(气味对象辨别)，来探索神经元组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.