Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

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.