Investigating cognitive functions mediated by ventral and dorsal striatum

研究腹侧和背侧纹状体介导的认知功能

• 批准号: RGPIN-2014-06621
• 负责人: MacDonald, Penny
• 金额: $ 1.73万
• 依托单位: University of Western Ontario
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=589122
• 关键词: Investigating; cognitive; functions; mediated; ventral

The aim of the proposed research is to better understand how learning, memory, and decision making are accomplished and the brain regions that produce these complex cognitive processes. This project is unique in focusing on the contributions of a subcortical structure called the striatum to these higher-order functions. Subcortical brain structures are formed by clusters of cells deep to the outer cell layers that form the cerebral cortex. These subcortical brain structures evolved earlier than the cortex, and are generally implicated in more primitive or automated functions. The striatum is widely understood to regulate movements. Increasingly, however, the striatum is ascribed a role in thinking processes as well. In fact, the striatum separates into ventral (i.e., toward the belly) and dorsal (i.e., toward the back) parts, with each appearing to underlie a different set of cognitive processes. These lists are far from fully defined, however. Using functional magnetic resonance imaging (fMRI), which allows measurement of blood flow as an index of regional brain activity, and various tests of learning, memory, and decision making, the aim is to better define the specific process(es) performed by ventral and dorsal striatum. The notion is that by comparing a number of skills, tasks, or conditions that preferentially engage each of these regions, and understanding what these scenarios have in common, we can deduce the specific computation(s) performed by ventral and dorsal striatum. From reviewing the existing literature, as well as my own recent research, the expectation is that ventral striatum will be implicated in general learning processes, not limited to the specific case of learning from reward, as had been thought. In contrast, dorsal striatum is not predicted to mediate early learning, though it has previously been linked to learning motor responses or skills. Rather, the expectation is that the dorsal striatum underlies decision making processes, particularly in ambiguous contexts. A further aim of this research will be to clarify how these subcortical structures interact with regions of cortex, and to understand the specific functions accomplished by ventral and dorsal striatum. Toward this goal, we will employ different fMRI analyses that focus on regions that are connected by their function or anatomy (e.g., connectivity analyses, diffusion tensor imaging) or that segregate from one another in terms of function (e.g., independent components analyses). An additional means for dissociating the specific functions accomplished by ventral and dorsal striatum relative to cortical regions to which they are connected, is to temporarily disable activity in cortical regions that are known to partner with striatum and to observe how behaviour and fMRI activity changes. In the proposed research, temporarily and reversibly depressed function of small and well-localized regions of cortex will be accomplished using a technique called repetitive transcranial magnetic stimulation, before participants perform specific tasks in the fMRI scanner. Taken together, this research programme aims to clarify the particular cognitive operations performed by the ventral and dorsal striatum, independent of their cortical partners. This research has the potential to augment current theories of attention, learning, and decision making. These theories ultimately have broad implications, informing public safety practices (e.g., traffic/driver safety), guiding educational policies and practices, and can be applied to understand and improve decision making in contexts such as industry or law.

这项研究的目的是为了更好地理解学习、记忆和决策是如何完成的，以及产生这些复杂认知过程的大脑区域。这个项目的独特之处在于，它专注于一种被称为纹状体的皮层下结构对这些高阶功能的贡献。大脑皮层下结构是由深层到外层形成大脑皮层的细胞群形成的。这些皮层下的大脑结构比皮层进化得更早，通常与更原始或自动化的功能有关。纹状体被广泛理解为调节运动。然而，纹状体在思维过程中也扮演着越来越重要的角色。事实上，纹状体分为腹侧（即朝向腹部）和背侧（即朝向背部）两个部分，每个部分似乎都是一套不同的认知过程的基础。然而，这些列表远未完全定义。