Aging can bring about various changes in our bodies, and one of the most noticeable ones is a decline in memory function. However, not all older adults experience this decline at the same rate.
A recent study conducted by psychologists at the University of Arizona sought to unravel the factors contributing to memory decline in some older individuals. The research also delved into aspects that affect memory in both younger and older people.
The study pinpointed the hippocampus, a region in the brain associated with memory and navigation, as a potential contributor to difficulties in learning new environments and locations in some older adults.
Li Zheng, a research scientist in the Department of Psychology and the lead author of the study, highlighted that neural representations within the hippocampus could elucidate why some individuals struggle to remember locations.
Zheng emphasized that these findings could prove valuable in predicting the extent of memory decline in the early stages of dementia, offering potential insights into diagnosing and managing this condition.
Published in the Proceedings of the National Academy of Sciences, this study draws inspiration from a similar investigation conducted in rats by Carol Barnes, a Regents Professor specializing in psychology, neurology, and neuroscience.
Barnes’ research explored “place cells,” specialized neurons in the hippocampus that activate when a person or animal enters a specific place, aiding in mental mapping of different spaces.
The study in rats observed that older rats had more difficulty in “remapping” for various environments compared to younger rats, indicating a decline in spatial memory performance with age.
Building upon Barnes’ work, Zheng and her team recruited 25 younger adults and 22 older adults, all in good health, to participate in a virtual reality experiment.
In this experiment, participants memorized the layouts and locations of six shops in two virtual cities displayed on a computer screen.
As participants tested their spatial memory through a series of questions, the researchers simultaneously used functional magnetic resonance imaging (fMRI) to scan the participants’ brains, capturing neural signals within the hippocampus.
The results aligned with Barnes’ findings, as older adults displayed neural representations that struggled to differentiate between environments compared to their younger counterparts.
However, the study unveiled an age-independent factor influencing memory retention. Zheng explained that distinct neurons in the hippocampus serve different functions, such as responding to the shape of an environment or the ground color.
These neurons collaborate to create a comprehensive representation of the entire environment. When a group of neurons takes on the same function, the fidelity of neural signals diminishes, compromising their accuracy.
Arne Ekstrom, a professor of cognition and neural systems at UArizona and a senior author of the study, pointed out that individuals with poor memory performance exhibit lower-fidelity neural signals, a factor unrelated to age.
The study also identified an age-dependent factor related to the quality of neural signals originating from other parts of the brain into the hippocampus.
Even high-performing older adults in the experiment exhibited a decrease in the quality of incoming neural signals into the hippocampus.
This finding suggests that changes in plasticity in the aging brain may affect the quality of signals entering specific brain regions, influencing memory.
These insights into the remapping index and fidelity of neural signals hold promise for predicting the extent of memory decline in individuals diagnosed with dementia.
In the near future, the research team plans to replicate the study using immersive virtual reality experiments that incorporate body-based cues and navigation, providing a more naturalistic approach to understanding memory decline in older adults.
If you care about Alzheimer’s disease, please read studies about These places in U.S. have the most cases of Alzheimer’s disease and findings of Scientists confirm the link between COVID-19 and Alzheimer’s disease.
For more information about brain health, please see recent studies about The power of healthy fats for brain health and results showing that Mediterranean diet may preserve brain volume in older adults.
The research findings can be found in PNAS.
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