Temporal instability weakens entorhinal grid-like coding in older adults
- 1DZNE
Abstract
Entorhinal grid cell representations are thought to support spatial navigation and episodic memory, functions that decline with age. Their putative fMRI correlate, the hexadirectional signal, varies markedly among older adults, but the source of this variability is unknown. Using virtual navigation and fMRI in 85 older adults, we tested whether signal strength was related to the stability of hexadirectional signals. Hexadirectional orientation stability, the cross-run reproducibility of direction-specific activity patterns, was associated with hexadirectional signal strength in the posterior-medial-entorhinal-cortex (pmEC). In left-pmEC, higher orientation stability also predicted better object-location memory. In contrast, age and local structural measures did not account for individual differences in either measure. Finally, retrosplenial absolute-orientation stability was associated with left-pmEC orientation stability, and a mediation analysis supported an indirect association with hexadirectional signals through pmEC orientation stability. Together, these findings suggest that weaker entorhinal hexadirectional signal in aging may reflect unstable, rather than absent, entorhinal grid-cell-like representations.
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BibTeX
@misc{segen2026temporal,
title = {{Temporal instability weakens entorhinal grid-like coding in older adults}},
author = {V. Segen and G. Callau Navarro and P. Bahrd and T. Belge Bernard and J.-I. Schinke and T. Wolbers},
howpublished = {bioRxiv},
year = {2026},
month = oct,
doi = {10.64898/2026.10.15.759328},
url = {https://www.biorxiv.org/content/10.64898/2026.10.15.759328v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Temporal instability weakens entorhinal grid-like coding in older adults
AU - V. Segen
AU - G. Callau Navarro
AU - P. Bahrd
AU - T. Belge Bernard
AU - J.-I. Schinke
AU - T. Wolbers
PY - 2026
DA - 2026/10/15
PB - bioRxiv
DO - 10.64898/2026.10.15.759328
UR - https://www.biorxiv.org/content/10.64898/2026.10.15.759328v1
AB - Entorhinal grid cell representations are thought to support spatial navigation and episodic memory, functions that decline with age. Their putative fMRI correlate, the hexadirectional signal, varies markedly among older adults, but the source of this variability is unknown. Using virtual navigation and fMRI in 85 older adults, we tested whether signal strength was related to the stability of hexadirectional signals. Hexadirectional orientation stability, the cross-run reproducibility of direction-specific activity patterns, was associated with hexadirectional signal strength in the posterior-medial-entorhinal-cortex (pmEC). In left-pmEC, higher orientation stability also predicted better object-location memory. In contrast, age and local structural measures did not account for individual differences in either measure. Finally, retrosplenial absolute-orientation stability was associated with left-pmEC orientation stability, and a mediation analysis supported an indirect association with hexadirectional signals through pmEC orientation stability. Together, these findings suggest that weaker entorhinal hexadirectional signal in aging may reflect unstable, rather than absent, entorhinal grid-cell-like representations.
ER -