Rapid acquisition of arbitrary associations independent of the MTL: challenging current neurobiological theories of declarative memory

目前的陈述性记忆理论提出了哺乳动物大脑中两个互补的学习系统：一个是以大脑为中心的系统，它支持对任意关联的快速学习;另一个是以新皮质为中心的系统，它只能通过从多个相似的经验中提取统计概括来缓慢学习。与此模型相反，我们最近证明了快速收购新的任意协会严重失忆症患者广泛病变的内侧颞叶（MTL），包括海马复合体。这是通过“快速映射”（FM）实现的：一个支持MTL尚未完全发育的幼儿词汇习得的过程。前颞叶（ATL）病变的患者无法通过FM学习，这表明新皮层区域是FM学习的关键。拟议的一系列研究的第一个目标是进一步了解通过调频了解到的信息的性质。具体来说，为了进一步证明，通过FM学到的信息是陈述性的，我的目标是测试两个中心功能，区分陈述性和非陈述性记忆：通过FM和意识主体获得的新的任意协会的灵活性的新知识。拟议的研究的第二个目标是收集证据，通过FM学习是否涉及巩固过程或仅仅是神经适应。最后，第三个目标是更好地理解FM学习的独特之处，并使其能够将新的语义信息直接整合到现有的新皮层网络中。我想测试的是，这是否只适用于完全新颖的信息，但这些信息嵌入在现有的分类知识结构中。整体科学方法将涉及健康成人和MTL病变后健忘症患者以及ATL损伤患者的行为调查，采用病变缺陷以及功能性神经成像和功能和有效连接的网络分析。

Current theories of declarative memory propose two complementary learning systems in the mammalian brain: a hippocampal-centered system that supports rapid learning of arbitrary associations, and a neocortical-centered system that only learns slowly by extracting statistical generalities out of multiple similar experiences. Contrary to this model, we recently demonstrated rapid acquisition of novel arbitrary associations by severely amnesic patients with extensive lesions to the Medial Temporal Lobe (MTL) including the hippocampal complex. This was achieved through "Fast Mapping" (FM): A process that supports vocabulary acquisition in toddlers in whom the MTL is not fully developed. Patients with Anterior Temporal Lobe (ATL) lesions were unable to learn through FM, suggesting that neocortical region is critical for FM learning. The first objective of the proposed set of studies is to further understand the nature of the information learned through FM. Specifically, to further demonstrate that the information learned through FM is declarative I aim to test two central features that distinguish declarative and non-declarative memory: the flexibility of the novel arbitrary associations acquired through FM and the awareness subjects have of the novel knowledge. The second objective of the proposed research is to gather evidence as to whether learning through FM involves consolidation processes or merely neural adaptation. Finally, the third aim is to better understand what makes FM learning unique and allows it to putatively incorporate novel semantic information directly into existing neocortical networks. I would like to test is whether this can only work for completely novel information, but which is embedded within existing categorized knowledge structures. The overall scientific approach will involve behavioural investigations in healthy adults and patients with amnesia following MTL lesions and patients with ATL damage, employing the lesion-deficit as well as functional neuroimaging and network analyses of functional and effective connectivity.