Our memories are as diverse as the lives that create them, but one thing that most memories have in common is a connection to the time and place at which they were formed. With the help of smartphones strapped around volunteers' necks, scientists found that the physical location of memories in the brain is directly based on these two key components.
The smartphones randomly snapped photos over the course of a month, providing a record of the time and place that the volunteers were forming particular memories, such as in a 9 a.m. class, on an afternoon stroll around campus, or grabbing frozen yogurt with friends for dessert after a long day. When the researchers invoked those memories later on by showing the volunteer the photos, they also monitored their brain activity using functional MRI, or fMRI. By comparing the location of the photo-spurred brain activity – the memory – with the record of the actual time and location of the photo, the researchers were able to study memory in a new way that yielded new insights, which are detailed in a paper in the journal Proceedings of the National Academy of Sciences.
"This is the first time we have been able to study real-life memories on such large spatial and temporal scales," senior study author Per Sederberg of Ohio State University told Tech Times. "Although rigorous memory research goes back over a century, recently there has been a push to take the study of memory out of the lab and into real life."
This approach revealed that memories that are further apart in space in time are physically stored farther apart in a region deep in the center of the brain known as the hippocampus.
"Whereas previous work had identified that the hippocampus is critical to memory formation and also activates when remembering autobiographical memories, this study demonstrates that the hippocampus actually represents the spatiotemporal information associated with those memories," Sederberg explained.
The fact that this spatiotemporal information is stored in the anterior, or near the front, portion of the hippocampus in particular provides some of the first direct support for an emerging theory that the anterior hippocampus is critical for representing the gist of our experiences. Sederberg hopes this finding could help researchers find a way to preserve the past in brains suffering from memory disorders.
"Given that this is one of the first regions to degrade in Alzheimer's, these results suggest that at least [in] early-stages of dementia, individuals may be able to form new memories, but suffer from an inability to retrieve them," said Sederberg. "I hope to explore this in future research by studying how older participants with mild cognitive impairment represent their real-life experiences and how these representations change as they develop more severe dementia."
Photo: Andrew Mason | Flickr