Brains Slow Down Network Connections as Memories Age

Published on May 16, 2022

Imagine your brain as a bustling city, with different neighborhoods representing different networks that help you remember things. As you get older, some of these networks start to lose their efficiency and connections between them become weaker. This can make it harder for your brain to consolidate memories, leading to memory decline. A group of scientists used functional magnetic resonance imaging (fMRI) to study the effects of aging on memory consolidation. They found that older adults had decreased connectivity within the ventral stream network and between other key networks in the brain during consolidation. Essentially, the connections between important brain neighborhoods were slowing down. These findings suggest that inefficient consolidation is one factor contributing to age-related memory decline. Understanding how these networks work together could help develop strategies to support memory function in older adults. So, if you’re curious about the inner workings of your brain and how aging affects memory, check out the full research article!

Aging is associated with memory decline and progressive disabilities in the activities of daily living. These deficits have a significant impact on the quality of life of the aging population and lead to a tremendous burden on societies and health care systems. Understanding the mechanisms underlying aging-related memory decline is likely to inform the development of compensatory strategies promoting independence in old age. Research on aging-related memory decline has mainly focused on encoding and retrieval. However, some findings suggest that memory deficits may at least partly be due to impaired consolidation. To date, it remains elusive whether aging-related memory decline results from defective consolidation. This study examined age effects on consolidation-related neural mechanisms and their susceptibility to interference using functional magnetic resonance imaging data from 13 younger (20–30 years, 8 female) and 16 older (49–75 years, 5 female) healthy participants. fMRI was performed before and during a memory paradigm comprised of encoding, consolidation, and retrieval phases. Consolidation was variously challenged: (1) control (no manipulation), (2) interference (repeated stimulus presentation with interfering information), and (3) reminder condition (repeated presentation without interfering information). We analyzed the fractional amplitude of low-frequency fluctuations (fALFF) to compare brain activity changes from pre- to post-encoding rest. In the control condition, fALFF was decreased in the left supramarginal gyrus, right middle temporal gyrus, and left precuneus but increased in parts of the occipital and inferior temporal cortex. Connectivity analyses between fALFF-derived seeds and network ROIs revealed an aging-related decrease in the efficiency of functional connectivity (FC) within the ventral stream network and between salience, default mode, and central executive networks during consolidation. Moreover, our results indicate increased interference susceptibility in older individuals with dynamics between salience and default mode networks as a neurophysiological correlate. Conclusively, aging-related memory decline is partly caused by inefficient consolidation. Memory consolidation requires a complex interplay between large-scale brain networks, which qualitatively decreases with age.

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