Dissecting the neural circuitry for spatial working memory

 描述(由申请者提供)：工作记忆是几乎所有行为的核心认知功能。尽管我们知道哪些大脑区域和哪些神经调节器参与了工作记忆，但我们对哪些神经元需要被激活以及何时启动工作记忆知之甚少。我们知识中的这种鸿沟之所以出现，是因为在操作和监测足够高的时间分辨率的遗传学和解剖学定义的细胞类型中的神经活动方面存在技术困难。为了克服这一挑战并阐明工作记忆的一些因果神经动力学，我们建议结合多种协同方法，包括我们先前建立的以多巴胺能神经元为靶点的大鼠光遗传模型，活体电生理记录，以及基于荧光的自由行为动物神经活动的监测(使用gCaMP6)。在目标1中，我们将在更新、维护或读出工作记忆的过程中，通过光遗传学抑制几个皮质和纹状体回路Eter，以确定每个回路支持工作记忆的哪一个方面。在AIMS 2中，我们将使用gCaMP6来监测多巴胺能神经元中的神经活动，以确定多巴胺能动力学如何与工作记忆表现相关。在目标3中，我们将产生不同模式的多巴胺能刺激(例如，强直性和相位性)，以确定工作记忆表现和多巴胺能活动动力学之间的因果关系。在目标4中，我们将多巴胺能刺激与背侧纹状体和前皮质的电生理记录相结合，以分离 多巴胺能活动介导的神经活动的下游变化。总之，这项工作将为工作记忆背后的神经回路机制提供新的见解，对基础科学和理解各种精神障碍中的工作记忆功能障碍都有意义。

 DESCRIPTION (provided by applicant): Working memory is an essential cognitive function central to virtually all behaviors. Despite the fact that we know which brain areas and which neuromodulators are involved in working memory, we know very little about which neurons need to be activated when to enable working memory. This gap in our knowledge arose because of the technical difficulty in manipulating and monitoring neural activity in genetically- and anatomically- defined cell-types with sufficiently high temporal resolution. In order to overcome this challenge and elucidate some of the causal neural dynamics for working memory, we propose to combine multiple synergistic approaches, including a rat optogenetic model that we have previously developed to target dopaminergic neurons, in vivo electrophysiological recordings, and fluorescence-based monitoring of neural activity in freely behaving animals (with gCaMP6). In Aim 1, we will optogenetically inhibit several cortical and striatal circuits eiter during the updating, maintenance, or readout of working memory to determine which aspect of working memory each circuit supports. In Aims 2, we will monitor neural activity in dopaminergic neurons using gCaMP6 to determine how dopaminergic dynamics correlate with working memory performance. In Aim 3, we will generate different patterns of dopaminergic stimulation (e.g. tonic vs phasic) to determine the causal relationship between working memory performance and dopaminergic activity dynamics. In Aim 4, we will integrate dopaminergic stimulation with electrophysiological recordings in dorsal striatum and prelimbic cortex to isolate the downstream changes in neural activity mediated by dopaminergic activity. Together, this work will provide new insights into the neural circuit mechanisms underlying working memory, with implications for both basic science and an understanding of the working memory dysfunction in various psychiatric disorders.