The Functional Role of Hippocampal Subregions and Subfields: A High-Resolution fMRI Study of Memory

• Author / Creator

  MacGillivray, Melanie, C

• The involvement of the hippocampus in episodic memory is well accepted. What is often overlooked is the involvement of hippocampal subfields and subregions. The hippocampal subfields Cornu Ammonis (CA), Dentate Gyrus (DG) and Subiculum (Sub) are cellularly distinct areas that communicate transversely across the hippocampus, while hippocampal subregions (Head, Body & Tail) are delineated from anterior to posterior along the length of the hippocampus and have different cortical connectivity. The current study addressed the question of how hippocampal subfields and subregions are involved in the encoding of episodic memory using high-resolution fMRI and an adaptation of the Wechsler Memory Scale Designs Subtest (2009). Our memory tasks consisted of 3 conditions: Symbol (content memory), Location (spatial memory) and Both (associative memory). We found that the total hippocampus was active for the Symbol, Location and Both conditions. All subfields and subregions were active across all conditions of the task relative to baseline. DG activity was significantly larger than CA activity when averaged across conditions. For the Location condition the hippocampal tail was more active than the hippocampal body, suggesting it may play a more dominant role in spatial memory. In addition hemisphere by subfield and subfield by condition interactions were observed. Our results provide support for the theory of posterior hippocampal involvement in spatial memory, and suggest the human hippocampus works in discrete but connected subsections to encode episodic memory.

• Subjects / Keywords

  • Memory
  • Hippocampus

• Graduation date

  Fall 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3R20S96T

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.