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一个关键挑战。海马体参与情景记忆已被广泛接受。海马体损伤导致广泛的记忆障碍，包括所有模式，并延伸到多个领域。在人类中，海马体沿着前后轴被细分为亚区：海马体头部、体和尾。除了大规模的解剖亚区，海马体是一个异质结构，可以进一步划分为几个组织学定义的亚区，包括锥体、齿状回和下骨。***已经提出，每个海马亚区和子场可能与不同的记忆功能相关联。然而，大多数结构和功能磁共振成像（MRI）研究将海马体作为单一结构或单个亚区内的海马体亚区进行检查。因此，有必要了解记忆是如何在整个海马体中组织起来的，这既是为了预测疾病进程或医疗干预将如何影响记忆的许多功能，也是为了降低记忆丧失的风险。***虽然传统的功能磁共振成像采集序列没有足够的空间分辨率来识别单个海马亚区和子场，但最近的人类高场功能磁共振成像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提案将通过应用一种新的高分辨率高场fMRI技术来扩展我们之前对海马体的研究，以确定人类海马体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不同区域之间是否存在区别，以及每个区域对正常记忆表现的贡献。***这些知识对于预测疾病进程或医疗干预将如何影响记忆功能以及减少记忆丧失的风险都是必不可少的。在短期内，我们的目标是揭示海马体内不同分支所支持的特殊作用，以及它们与其他内侧颞叶结构的独特相互联系。从长远来看，更好地了解记忆是如何在海马体中组织起来的，对于预防和治疗各种疾病的记忆缺陷都是至关重要的。fMRI扫描将在Peter S. Allen MR研究中心的4.7特斯拉扫描仪上进行，该中心是生物医学工程系的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.