Aging alters neural activity at event boundaries in the hippocampus and Posterior Medial network

Zachariah M Reagh,Alexander Garber,Charan Ranganath,Angelique I Delarazan

doi:10.1038/s41467-020-17713-4

Zachariah M Reagh, Alexander Garber + Show 2 more

Open Access

https://doi.org/10.1038/s41467-020-17713-4

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Abstract

Recent research has highlighted a role for the hippocampus and a Posterior Medial cortical network in signaling event boundaries. However, little is known about whether or how these neural processes change over the course of healthy aging. Here, 546 cognitively normal participants 18–88 years old viewed a short movie while brain activity was measured using fMRI. The hippocampus and regions of the Posterior Medial network show increased activity at event boundaries, but these boundary-evoked responses decrease with age. Boundary-evoked activity in the posterior hippocampus predicts performance on a separate test of memory for stories, suggesting that hippocampal activity during event segmentation may be a broad indicator of individual differences in episodic memory ability. In contrast, boundary-evoked responses in the medial prefrontal cortex and middle temporal gyrus increase across the age range. These findings suggest that aging may alter neural processes for segmenting and remembering continuous real-world experiences.

Highlights

Recent research has highlighted a role for the hippocampus and a Posterior Medial cortical network in signaling event boundaries
The hippocampus is known to interact closely with two large-scale cortical networks: a Posterior Medial (PM) network that is more affiliated with the posterior hippocampus, and an Anterior Temporal (AT) network that is more affiliated with the anterior hippocampus
Given that aging is consistently associated with changes in episodic memory[18], and with changes in hippocampal[19,20] and PM network function[21,22,23], we hypothesized that aging would disrupt neural responses in these regions at event boundaries

Summary

Introduction

Recent research has highlighted a role for the hippocampus and a Posterior Medial cortical network in signaling event boundaries. In pHPC, we observed significant boundary-evoked activity (t(545) = 31.266, p = 1.11e−123) that decreased significantly with age across the sample (r = −0.345, p = 1.06e−16) (Fig. 1a; see Supplementary Fig. 1 for unadjusted data).

Results

Conclusion