The hippocampus as an indexing machine of episodic memory

Kolibius, Luca Dominik (2023) The hippocampus as an indexing machine of episodic memory. PhD thesis, University of Glasgow.

Abstract

Episodic memories refer to our ability to encode and reinstate experiences. By extension, these memories shape how we view ourselves and the world around us. Despite this, little is known about how neurons in the hippocampus encode and retrieve new episodes. Here, I will demonstrate evidence for single neurons in the human hippocampus that code specific episodic memories (hence called Episode Specific Neurons), both through a rate code and a temporal code. Importantly, these neurons cannot be construed as coding for specific timepoints or concepts. Next, I will extend these findings to population activity in the local field potential. I report evidence for a reinstatement in high frequency power during successful memory processing that mirrors earlier findings in single neurons. Again, these results cannot be explained by activity induced by a content-code. Despite the undisputed importance of theta activity in memory processing, we find no consistent evidence of an increase in theta power during memory processing. Likewise, we find no evidence that earlier identified Episode Specific Neurons or other hippocampal neurons fire preferentially at a particular theta phases or theta phase offsets between encoding or retrieval of episodic memories. Lastly, I embed these findings in the broader literature, identify future experiments, and discuss possible translational applications.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: R Medicine > RC Internal medicine > RC0321 Neuroscience. Biological psychiatry. Neuropsychiatry
• Colleges/Schools: College of Medical Veterinary and Life Sciences > School of Psychology & Neuroscience
• Supervisor's Name: Hanslmayr, Professor Simon, Bowman, Professor Howard and Wimber, Professor Maria
• Date of Award: 2023
• Depositing User: Theses Team
• Unique ID: glathesis:2023-83611
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 30 May 2023 09:02
• Last Modified: 30 May 2023 16:12
• Thesis DOI: 10.5525/gla.thesis.83611
• URI: https://theses.gla.ac.uk/id/eprint/83611