Neural mechanisms underlying recognition memory

这项研究的首要目标是了解大脑是如何支持记忆的。众所周知，长期记忆依赖于大脑深处一组紧密相连的结构，这些结构构成了所谓的内侧颞叶（MTL）。大多数记忆研究人员认为，MTL中的这些结构形成了一个专门用于长期记忆的系统，这意味着这些结构在任何其他认知过程中没有作用，如感知，注意力或工作记忆。这种观点与认知神经科学中的一种流行范式是一致的，在这种范式中，大脑被理解为整齐分离的区域或认知模块，每个区域或认知模块负责不同的广泛心理功能。在这个框架内，有人认为，不同的大脑系统解释了不同的认知过程，如“长期记忆”、“工作记忆”或“感知”。拟议中的研究将表明，这种观点既不是最吝啬的，也不是最令人信服的数据。虽然很明显，MTL中的结构对记忆是必不可少的，但最近的研究结果表明，这些MTL结构确实在感知中起着关键作用-这一发现与专门的MTL记忆系统或更普遍的认知模块的概念根本不相容。与记忆的模块化观点相反，拟议中的研究将使用神经心理学和神经成像技术来证明大脑区域的功能可以根据它们所代表的信息类型和它们执行的计算来更好地理解。这项研究将表明，MTL应被视为属于腹侧视觉流，一个连续的层次结构的区域，逐渐增加的复杂性，他们处理的信息。我们建议，而在腹侧视觉流较低的区域负责代表组成对象的简单功能，嗅周皮层（PRC）-目前被认为是MTL记忆系统的一个关键结构-坐在这个腹侧视觉流层次的顶峰。我们认为，一个关键的功能，中华人民共和国是代表的复杂组合的功能，包括整个对象，并将证明这些复杂的“对象级”中华人民共和国表示是什么让我们能够细粒度的区分具有相似功能的对象之间。重要的是，我们将证明，这种区分视觉相似物体的能力的丧失并不像通常认为的那样导致记忆丧失，而是导致对以前从未见过的物体的自相矛盾的错误记忆。这个项目旨在重新定义当前的记忆概念，将重点从解释专门的认知模块（例如，对于长期记忆或感知），而不是解释认知过程的基础信息是如何在大脑中表示的。此外，通过使用趋同技术-使用现代认知范式和最先进的神经成像的行为研究-该项目将提供特殊的研究培训机会，加强加拿大的知识型经济。

The overarching goal of the proposed research is to understand how the brain supports memory. It is well-established that long-term memory relies on a set of heavily interconnected structures deep inside the brain that make up what is called the medial temporal lobe (MTL). Most memory researchers believe that these structures in the MTL form a system that is solely dedicated to long-term memory, meaning that these structures have no role in any other cognitive processes such as perception, attention, or working memory. This view is consistent with a popular paradigm in cognitive neuroscience, in which the brain is understood in terms of neatly segregated regions or cognitive modules that are each responsible for different broad psychological functions. Within this framework, it is argued that separate brain systems account for distinct cognitive processes, like “long-term memory,” “working memory,” or “perception.” The proposed research will suggest that this view is neither the most parsimonious nor the most compelling account of the data. Although it is clear that the structures in the MTL are essential for memory, recent findings indicate that these MTL structures do, in addition, play a critical role in perception – a finding that is fundamentally incompatible with the notion of a dedicated MTL memory system specifically, or cognitive modules more generally. In contrast to a modular view of memory, the proposed research will use neuropsychological and neuroimaging techniques to demonstrate that the functions of brain regions can be better understood in terms of the types of information they represent and the computations they perform. This research will suggest that the MTL should be considered as belonging to the ventral visual stream, a continuous hierarchy of regions that gradually increase in the complexity of information that they process. We propose that whereas regions lower down in the ventral visual stream are responsible for representing the simpler features that make up objects, the perirhinal cortex (PRC) – a key structure of what is currently thought to be the MTL memory system – sits at the peak of this ventral visual stream hierarchy. We argue that a critical function of the PRC is to represent the complex combinations of features that comprise whole objects, and will demonstrate that these complex “object-level” PRC representations are what allow us to make fine-grained distinctions between objects that have similar features. Importantly, we will show that the loss of this ability to discriminate between visually similar objects leads not to memory loss, as is commonly assumed, but rather to a paradoxical false memory for objects that were never seen before. This project stands to redefine current conceptions of memory by shifting the focus away from explaining functions in terms of specialized cognitive modules (e.g., for long-term memory or perception), and instead towards explaining cognitive processes in terms of how the underlying information is represented in the brain. In addition, through the use of convergent techniques – behavioural studies using modern cognitive paradigms and state-of-the-art neuroimaging – this project will provide exceptional research training opportunities that will strengthen Canada’s knowledge-based economy.