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: 2014
• 资助国家: 加拿大
• 起止时间: 2014-01-01 至 2015-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=567930
• 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.

这项研究的目的是更好地了解学习、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关注了一种叫做纹状体的皮质下结构对这些高阶功能的贡献。皮层下大脑结构由形成大脑皮层的细胞簇形成。这些皮层下的大脑结构比皮层进化得更早，并且通常涉及更原始或自动化的功能。纹状体被广泛理解为调节运动。然而，越来越多的人认为纹状体也在思维过程中发挥作用。事实上，纹状体分为腹侧（即，朝向腹部）和背部（即，朝后）的部分，每一个似乎是一套不同的认知过程的基础。然而，这些清单远未完全确定。 使用功能性磁共振成像（fMRI），它允许测量血流作为局部大脑活动的指标，以及学习，记忆和决策的各种测试，目的是更好地定义腹侧和背侧纹状体执行的特定过程。这个概念是，通过比较优先使用这些区域的一些技能，任务或条件，并了解这些场景的共同点，我们可以推断腹侧和背侧纹状体执行的特定计算。回顾现有的文献，以及我自己最近的研究，我们的期望是腹侧纹状体将涉及一般的学习过程，而不限于奖励学习的具体情况，正如人们所认为的那样。相反，背侧纹状体不被预测为介导早期学习，尽管它以前被认为与学习运动反应或技能有关。相反，人们期望背侧纹状体是决策过程的基础，特别是在模棱两可的情况下。本研究的进一步目的是阐明这些皮质下结构如何与皮质区域相互作用，并了解腹侧和背侧纹状体完成的特定功能。为了实现这一目标，我们将采用不同的功能磁共振成像分析，重点是通过其功能或解剖结构连接的区域（例如，连接性分析，扩散张量成像）或在功能方面彼此分离（例如，独立成分分析）。分离腹侧和背侧纹状体相对于它们所连接的皮质区域完成的特定功能的另一种方法是暂时禁用已知与纹状体合作的皮质区域的活动，并观察行为和fMRI活动如何变化。在拟议的研究中，在参与者在功能磁共振成像扫描仪中执行特定任务之前，将使用一种称为重复经颅磁刺激的技术来完成皮质小区域和局部区域的暂时和可逆性抑制功能。 总之，这项研究计划的目的是澄清腹侧和背侧纹状体执行的特定认知操作，独立于他们的皮质伙伴。这项研究有可能增强当前的注意力，学习和决策理论。这些理论最终具有广泛的影响，为公共安全实践提供信息（例如，交通/驾驶员安全），指导教育政策和实践，并可用于理解和改善行业或法律等背景下的决策。