Remembering what happened to us is more than just looking back to the past. The memories our brains store and we later recall affect who we are, how we behave, and how we connect with others. Morgan Barense, a cognitive neuroscientist at the University of Toronto, believes in that.
As people age, it becomes harder to remember specific details of past experiences, and the loss of vividness in people's memories significantly worsens their qualities of life (1). “When you start to lose your memory for the past, that can be really disorienting because you feel disconnected, not only from the things that you've done, but who you are as a person,” said Barense.
In a study published in the Proceedings of the National Academy of Sciences, a group of researchers led by Barense showed that a mobile memory intervention they developed helped older adults preserve detail rich memories. They also provided evidence of the patterns of brain activity in the hippocampus associated with that memory enhancement (2).
Barense’s team created the mobile application, named HippoCamera, to virtually mimic some of features of the hippocampus. This brain region supports memory recall, and a reduction in hippocampal volume and function is linked to age-related memory decline (3,4). “[We took] fundamental principles from cognitive psychology and a bit of what we know about how the hippocampus supports memory (timing around memory consolidation, aspects of hippocampal replay) and put them into an easy to use application,” said Barense.
For the study, the researchers recruited older adults aged 61 to 76 years and asked them to use the smartphone app for either two or ten weeks. The participants recorded short videos of events they wanted to remember along with a brief verbal description of each event. The app automatically assigned some of these memories to be replayed, while others were not. The scientists then tested the participants’ memories by asking them to describe everything they recalled about each event.
The researchers found that replaying the self-generated memory clips improved the recollection of these experiences, and the participants remembered more than 50 percent more details about the replayed memories compared to the events they had recorded with HippoCamera but never replayed. “Every single person in this study benefited immediately and after three months,” said Barense. “That was really compelling for us to see.”
To characterize these memories better, the research team used a natural language analysis tool that quantifies and identifies the affective states people communicate through words. They found that reviewing memory clips led to more positive sentiments at recall, indicating that HippoCamera enables a positive recollection that may influence people’s emotional well-being.
Next, the researchers measured the participants’ hippocampus brain activities as they watched their memory clips and completed a memory test. The fMRI scans revealed that replaying memory cues with HippoCamera altered the pattern of activity within the hippocampus, making these everyday life experiences more distinctive and less overlapped with each other. That suggests that HippoCamera helps keep memories from different events separated from one another in the hippocampus.
Pattern separation is one possible explanation for the neuroimaging findings, said Craig Stark, a neuroscientist at the University of California, Irvine who was not involved in the study. “One of the things we think that a part of the hippocampus called the dentate gyrus does is to take very similar events, very similar memories, and pull them apart into different representations so that you can rapidly learn about these without having them interfere with each other,” he said. Yet, follow-up studies are still needed to determine whether pattern separation is the process underlying the observed brain changes and which molecular events might support them.
This study shows that a technological intervention can be incorporated into the lives of older adults, said Stark. “The system is always plastic, it's always malleable, it's always changeable. Your memory may be worse, but it's not that it's permanently perpetually worse.”
References
- Levine, B. et al. Aging and autobiographical memory: dissociating episodic from semantic retrieval. Psychol Aging 17, 677-689 (2002).
- Martin, CB. et al. A smartphone intervention that enhances real-world memory and promotes differentiation of hippocampal activity in older adults. Proc Natl Acad Sci USA 119, e2214285119 (2022).
- Tulving, E. & Markowitsch, H.J. Episodic and declarative memory: role of the hippocampus. Hippocampus. 8, 198-204 (1998).
- Nyberg, L. et al. Memory aging and brain maintenance. Trends in cognitive sciences 16, 292–305 (2012).
