Functional organization of the human hippocampus: insights from high-resolution functional magnetic resonance imaging.

了解记忆是如何在人脑中维持和储存的仍然是基础和临床神经科学的关键挑战。海马参与情景记忆的研究已被广泛接受。海马体的损伤导致广泛的记忆障碍，包括所有形式，并延伸到多个领域。在人类中，海马体沿着沿着前后轴被细分为子区域：海马体头、体和尾。除了大规模的解剖学亚区之外，海马是一种异质结构，可以进一步划分为几个组织学定义的亚区，包括角氨，齿状回和下托。有人认为，每个海马亚区和子区可能与不同的记忆功能。然而，大多数结构和功能磁共振成像（MRI）的研究已经检查了海马作为一个单一的结构或海马子域内的一个单一的子区域。因此，有必要了解整个海马体的记忆是如何组织的，以便预测疾病过程或医疗干预如何影响记忆的许多功能，并降低记忆丧失的风险。虽然传统的fMRI采集序列没有足够的空间分辨率来识别单个海马子区域和子场，但最近的人类高场fMRI研究提供了足够的空间分辨率（2mm或更小）来更精确地定位海马激活。我们的NSERC提案将通过应用新的高分辨率高场fMRI技术来扩展我们以前对海马的研究，以确定人类海马中的记忆系统是如何组织和相互作用的。我们将测试海马体中的各个分区之间是否存在区别，每个分区如何对正常的记忆表现做出贡献。这些知识对于预测疾病过程或医疗干预如何影响记忆功能以及降低记忆丧失的风险都至关重要。在短期内，我们的目标是揭示海马体内不同分区所支持的专门角色，以及它们与其他内侧颞叶结构的独特互连。从长远来看，更好地了解记忆在海马体中是如何组织的，对于改善预防和治疗各种疾病中的记忆缺陷至关重要。功能磁共振成像扫描将在彼得S.艾伦MR研究中心，生物医学工程系内的100%研究机构。* 拟议的研究将对记忆和海马体的神经生物学研究产生重大影响，并将有助于解释在较低场强和空间分辨率下获得的测量结果。

Understanding how memories are maintained and stored in the human brain remains a key challenge for both basic and clinical neuroscience. The involvement of the hippocampus in episodic memory is well accepted. Damage to the hippocampus results in broad memory impairment that includes all modalities and extends across multiple domains. In humans, the hippocampus is subdivided along the anteroposterior axis into subregions: the hippocampal head, body, and tail. Apart from large-scale anatomical subregions, the hippocampus is a heterogeneous structure that can be further delineated into several histologically-defined subfields, including the cornu ammonis, dentate gyrus, and subiculum.***It has been suggested that each hippocampal subregion and subfield could be associated with a distinct memory function. However, most structural and functional Magnetic Resonance Imaging (MRI) studies have examined the hippocampus as a single structure or hippocampal subfields within a single subregion. Therefore, it is necessary to understand how memories are organized across the entire hippocampus, both in order to predict how disease processes or medical interventions will affect the many functions of memory, and to reduce the risk or memory loss.***Although conventional fMRI acquisition sequences do not have sufficient spatial resolution to identify individual hippocampal subregions and subfields, recent human high-field fMRI studies provided sufficient spatial resolution (2mm or less) to localize hippocampal activations more precisely. Our NSERC proposal will extend our previous research on hippocampus by applying a new high resolution high field fMRI technique in order to determine how memory systems in the human hippocampus are organized and interact. We will test if there is a distinction between divisions in the hippocampus in how each contributes to normal memory performance.***This knowledge is essential both in order to predict how disease processes or medical interventions will affect memory functions, and to reduce the risk of memory loss. In the short term, we aim to uncover the specialized roles supported by different divisions within the hippocampus, as well as their unique interconnections with other medial temporal lobe structures. In the long term a better understanding of how memories are organized in the hippocampus is essential to improve both the prevention and the treatment of memory deficits across a wide range of diseases. fMRI scans will be performed on a 4.7 Tesla scanner at the Peter S. Allen MR Research centre, the 100% research facility within the Department of Biomedical Engineering. ***The proposed study will have significant implications for neurobiological studies of memory and hippocampus and will aid in the interpretation of measurements obtained at lower field strength and spatial resolution.