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，后颞叶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感知、注意力或工作记忆等任何其他认知过程中都没有作用。这一观点与认知神经科学中的流行范式是一致的，在认知神经科学中，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，不同的大脑系统负责不同的认知过程，如“长期记忆”、“工作记忆”或“感知”。拟议的研究将表明，这种观点既不是最简洁的，也不是最令人信服的数据解释。虽然MTL的结构对记忆至关重要，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——这一发现从根本上与专门的MTL记忆系统或更普遍的认知模块的概念不相容。

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.