Year: 2019
Type: dissertation
Abstract: The hippocampus plays a key role in establishing spatial and event boundaries, crucial for constructing and maintaining cognitive maps in spatial and non-spatial domains. The present set of studies investigated these processes in the context of navigating large-scale, virtual spaces (Google Street View) and viewing visual narratives (film). The first study is composed of two behavioural experiments that highlight the representational priority of turns along travelled routes. Locations associated with turns were recollected better and produced a temporal overestimation bias, compared with locations following turns. The second study presents an fMRI investigation of the interactions between hippocampal representations of decision points and navigational goals along familiar routes. The relationship between decision points and goal representations was modulated by goal proximity, and developed with experience in the virtual environment. This experience-related development suggests that hippocampal representations are reconfigured to represent the most relevant aspects of the environment. The third study presents an fMRI investigation of a large cross-sectional adult lifespan sample in which participants watched a movie. The hippocampus was the only region that consistently represented within-event details as unrelated or dissimilar, in a manner that was distinct from the neocortex. While most neocortical representations remained stable with age, the pattern overlap in the hippocampus, the anterior temporal lobe, and the orbitofrontal cortex increased significantly, suggesting a loss of precision and a potential susceptibility to interference. Together, these studies provide evidence that the representation and segmentation of the temporal flow of experience are key organizational features of episodic memory and navigation. These dimensions are captured in moment-to-moment hippocampal dynamics and malleable by different contexts.
Source: TSpace (University of Toronto)
Author: Iva K. Brunec
Language: English
Topic: Memory and Neural Mechanisms
Subfield: Cognitive Neuroscience
Field: Neuroscience
Domain: Life Sciences
Open Access status: green
Funder: Alzheimer Society
OpenAlex ID: W3144260762