Converging diencephalic and hippocampal supports for episodic memory

Aggleton, John P. ORCID: https://orcid.org/0000-0002-5573-1308, Vann, Seralynne D. ORCID: https://orcid.org/0000-0002-6709-8773 and O'Mara, Shane M. 2023. Converging diencephalic and hippocampal supports for episodic memory. Neuropsychologia 191 , 108728. 10.1016/j.neuropsychologia.2023.108728

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Abstract

To understand the neural basis of episodic memory it is necessary to appreciate the significance of the fornix. This pathway creates a direct link between those temporal lobe and medial diencephalic sites responsible for anterograde amnesia. A collaboration with Andrew Mayes made it possible to recruit and scan 38 patients with colloid cysts in the third ventricle, a condition associated with variable fornix damage. Complete fornix loss was seen in three patients, who suffered chronic long-term memory problems. Volumetric analyses involving all 38 patients then revealed a highly consistent relationship between mammillary body volume and the recall of episodic memory. That relationship was not seen for working memory or tests of recognition memory. Three different methods all supported a dissociation between recollective-based recognition (impaired) and familiarity-based recognition (spared). This dissociation helped to show how the mammillary body-anterior thalamic nuclei axis, as well as the hippocampus, is vital for episodic memory yet is not required for familiarity-based recognition. These findings set the scene for a reformulation of temporal lobe and diencephalic amnesia. In this revised model, these two regions converge on overlapping cortical areas, including retrosplenial cortex. The united actions of the hippocampal formation and the anterior thalamic nuclei on these cortical areas enable episodic memory encoding and consolidation, impacting on subsequent recall.

Item Type:	Article
Date Type:	Published Online
Status:	Published
Schools:	Psychology
Additional Information:	License information from Publisher: LICENSE 1: URL: http://creativecommons.org/licenses/by/4.0/, Start Date: 2023-11-08
Publisher:	Elsevier
ISSN:	0028-3932
Date of First Compliant Deposit:	10 November 2023
Date of Acceptance:	3 November 2023
Last Modified:	27 Nov 2023 15:28
URI:	https://orca.cardiff.ac.uk/id/eprint/163788

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