Journal Article

Hippocampal-cortical functional connectivity during memory encoding and retrieval

Walhovd, Kristine B., Grydeland, Håkon, Sørensen, Øystein, Vidal-Piñeiro, Didac, Raud, Liisa, Ness, Hedda T., Fjell, Anders M., Sneve, Markus H., Folvik, Line, Mowinckel, Athanasia M.

2023

Overview

•Distinct profiles for the anterior and posterior hippocampus.•Stable connectivity during resting state and memory tasks.•Upregulation of hippocampal connectivity with recollection areas during retrieval.•Sparse task-general connectivity during encoding when compared with retrieval. Memory encoding and retrieval are critical sub-processes of episodic memory. While the hippocampus is involved in both, less is known about its connectivity with the neocortex during memory processing in humans. This is partially due to variations in demands in common memory tasks, which inevitably recruit cognitive processes other than episodic memory. Conjunctive analysis of data from different tasks with the same core elements of encoding and retrieval can reduce the intrusion of patterns related to subsidiary perceptual and cognitive processing. Leveraging data from two large-scale functional resonance imaging studies with different episodic memory tasks (514 and 237 participants), we identified hippocampal-cortical networks active during memory tasks. Whole-brain functional connectivity maps were similar during resting state, encoding, and retrieval. Anterior and posterior hippocampus had distinct connectivity profiles, which were also stable across resting state and memory tasks. When contrasting encoding and retrieval connectivity, conjunctive encoding-related connectivity was sparse. During retrieval hippocampal connectivity was increased with areas known to be active during recollection, including medial prefrontal, inferior parietal, and parahippocampal cortices. This indicates that the stable functional connectivity of the hippocampus along its longitudinal axis is superposed by increased functional connectivity with the recollection network during retrieval, while auxiliary encoding connectivity likely reflects contextual factors.

• Publisher: Elsevier Inc,Elsevier Limited,Elsevier
• Subject: Age / Brain mapping / Cognitive ability / Cortex / Encoding / Episodic memory / Functional connectivity / Hippocampus / Information processing / Informed consent / Memory / Neocortex / Neural networks / Neuroimaging / Parahippocampal gyrus / Retrieval / Young adults