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Structural measurement, lesion distribution, and memory performance across 74 selective medial temporal lobe amnesics

Poster Session D - Monday, March 9, 2026, 8:00 – 10:00 am PDT, Fairview/Kitsilano Ballroom

Daniela Montaldi¹ (), Rowan Lawrence¹, Alex Kafkas¹, Laura Marsh², Michael Kopelman³, Robin Morris³, Dan Cox¹, Andrew Mayes¹; ¹University of Manchester, ²University of Cambridge, ³King's College London

Damage to the medial temporal lobe (MTL) is frequently found in clinical populations. However, selective hippocampal or MTL cortex (MTLc) damage is not only extremely rare, but very hard to confirm. Nonetheless, neuropsychological findings remain critical to the development and confirmation of theories of the cognitive neuroscience of memory. We describe the neural and behavioural patterns in a population of 74 selective MTL amnesics (age 24-71) and 80 matched healthy controls. Participants underwent high resolution 3T MRI scanning, including T1 and DTI, neuropsychological assessment, and experimental testing of memory, focusing on recollection and familiarity, across four types of stimulus information (words, scenes, objects, faces). Manual volumetry of the medial temporal lobes yielded relatively selective hippocampal (≈10%), MTL cortex (entorhinal, ERC, perirhinal PRC, and parahippocampal, PHC with intact hippocampus) (≈30%), and global MTL (MTLc plus hippocampal damage) (≈60%) patients. Using continuous modelling of regional volumes, ridge regression with subsequent hierarchical regression revealed that across all amnesics, ERC volume was the primary driver of memory performance for all memory tests, while hippocampal volume (particularly head and tail) was the key driver of tests of recall and recollection-based recognition. Categorical analyses demonstrated that hippocampal patients performed normally on the more familiarity-based recognition tasks, while MTLc patients (and global MTL patients) were impaired. As a two-way gateway between MTLc and hippocampus, the ERC is well-placed to support memory independent of task and material. These and other MTL findings are discussed in the context of memory theory and the optimization of neuropsychological studies of amnesia.

Topic Area: LONG-TERM MEMORY: Episodic