What this means
The hippocampus integrates spatial information from medial entorhinal cortex (MEC) with non-spatial sensory information from lateral entorhinal cortex (LEC) to form episodic memories. While age-related memory dysfunction is linked to several changes in neuronal function within hippocampal subfields, the effects of aging on MEC and LEC cellular activity patterns are less well-characterized.
A plain-English summary is on its way. Until then, this is the start of the authors' own summary.
- Who it was tested in
- Animals or cells
- Kind of research
- Research in animals or cells
The science
- Original title
- Age-related differences in behavior-driven activity in LEC but not MEC.
- Authors
- Lister JP, Comrie AE, Barnes CA
- Journal
- Cerebral cortex (New York, N.Y. : 1991)
- Published
- Oct 19, 2026
- Study type
- Lab or animal study · indexed as animal research
- PMID
- 42894381 ↗
Abstract
The hippocampus integrates spatial information from medial entorhinal cortex (MEC) with non-spatial sensory information from lateral entorhinal cortex (LEC) to form episodic memories. While age-related memory dysfunction is linked to several changes in neuronal function within hippocampal subfields, the effects of aging on MEC and LEC cellular activity patterns are less well-characterized. Here, we investigated MEC and LEC population activity in adult versus aged rats by monitoring the expression of the immediate early gene Arc across two behavioral task sessions with olfactory stimuli separated by a rest period. Aging did not affect the percentage of activated neurons in MEC or their consistent Arc expression patterns across sessions, consistent with stably coding repeated spatial experiences. In contrast, fewer LEC neurons were activated during behavior in aged than adult rats, indicating a specific age-associated hypoactivity in LEC. Additionally, regardless of group, more LEC neurons were activated during the second session compared to the first, which may reflect temporally sensitive LEC neuronal activity increasingly engaged across episodes of experience. These results indicate that aging affects input to the hippocampus in a region-specific manner and are also consistent with observations that suggest that some LEC neurons may provide a temporal tag for episodic memories.
Lister JP, Comrie AE, Barnes CA Age-related differences in behavior-driven activity in LEC but not MEC. Cerebral cortex (New York, N.Y. : 1991). 2026. doi:10.1093/cercor/bhag171. PMID: 42894381. https://pubmed.ncbi.nlm.nih.gov/42894381/