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Updated: Jun 26, 2026
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Assessment of Memory Function in Pilocarpine-induced Epileptic Mice
Published on: June 4, 2020
Working memory-related hippocampal deactivation interferes with long-term memory formation
Nikolai Axmacher1, Christian E Elger, Juergen Fell
1Department of Epileptology, University of Bonn, D-53105 Bonn, Germany. nikolai.axmacher@ukb.uni-bonn.de
Summary
Hippocampal activity patterns during memory tasks reveal insights into long-term memory (LTM) encoding and working memory (WM). Hippocampal deactivations during early list item processing predict LTM encoding failure, while activation suggests successful memory formation.
Area of Science:
- Neuroscience
- Cognitive Psychology
- Memory Research
Background:
- The hippocampus is crucial for long-term memory (LTM) encoding and working memory (WM), especially when processing multiple items.
- Studies show hippocampus-dependent WM involves activation, while hippocampus-independent WM involves deactivation during item maintenance.
Purpose of the Study:
- To investigate if WM-related activity patterns occur during LTM encoding of sequential items.
- To determine if these patterns relate to the primacy effect in LTM.
Main Methods:
- Utilized intracranial electroencephalogram (iEEG) in epilepsy patients and functional MRI (fMRI) in healthy subjects.
- Recorded brain activity during a word-list learning task.
Main Results:
- Confirmed the primacy effect: higher successful encoding rates for early list items.
- Items at the beginning of the list that were forgotten showed hippocampal deactivations, indicating non-hippocampus-dependent WM processing.
- These deactivations were absent for later list items and for remembered early list items.
Conclusions:
- Hippocampal activity patterns observed during WM processing are relevant to LTM encoding.
- Processing of early list items with hippocampus-dependent WM patterns leads to successful LTM encoding.
- Hippocampal deactivations during early list item processing predict LTM encoding failure.
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