Schedule of Events | Symposia

Cortical thickness and volume differences in individuals with Severely-Deficient Autobiographical Memory

Poster Session C - Sunday, March 30, 2025, 5:00 – 7:00 pm EDT, Back Bay Ballroom/Republic Ballroom

Shikang Peng^1,2 (speng@research.baycrest.org), Brian Levine^1,2; ¹Rotman Research Institute, Baycrest Health Sciences, ²University of Toronto

Humans have a unique ability to recall vivid personal past experiences, known as episodic autobiographical memory (AM). However, individuals with Severely Deficient Autobiographical Memory (SDAM), identified in 2015, lack this capacity for reliving past experiences. Despite this, they function normally in everyday life and have comparable performance on memory tasks, indicating possible compensatory mechanisms. Recent work using deep learning and neuroimaging revealed that individuals with SDAM show reduced neural communication between the early visual cortex and posterior hippocampus, suggesting reliance on semantic details. Furthermore, whereas normative samples show an R>L asymmetry in hippocampal volumes, people with SDAM show either no asymmetry or L > R. These findings suggest enhanced verbal-semantic processing in SDAM, which corresponds to their subjective reports of low or absent visual imagery. Here, we conducted a data-driven analysis on cortical thickness and volume data in a larger SDAM group with matched healthy controls, employing FreeSurfer to preprocess and parcellate the brain using the 68-ROI DK atlas. Overall, cortical thickness and volumes in SDAM were comparable to healthy controls, but there was subtle evidence of greater cortical thickness and volume in regions linked to semantic memory, including orbitofrontal and medial temporal areas in the SDAM group, who again showed greater or more balanced left-right hemisphere compared to healthy controls. This analysis suggests that inter-individual variation as expressed in SDAM may extend beyond functional properties, affecting trajectories of structural variation on a developmental basis.

Topic Area: LONG-TERM MEMORY: Episodic