Summary: According to a new study, people show similar brain activity when they share an experience and later go on to speak about their memory.
Source: Princeton University.
We tend to think of our memories as unique, but a Princeton University-led study shows that memories are often shared rather than idiosyncratic.
The findings appear in the journal Nature Neuroscience. The study included researchers from Princeton University (Hasson and Norman groups in the Princeton Neuroscience Institute), Stanford University, Johns Hopkins University and the University of Toronto.
Every person perceives the world in his or her own way and describes the past through the lens of individual history. However, human brains have much in common with one another in terms of anatomy and functional organization, and the capacity to share memories is essential for our ability to interact with others and form social groups. The processes by which shared experiences contribute to a community’s collective memory have been extensively studied, but relatively little is known about how shared experiences shape memory in the brains of people who are engaged in spontaneous natural recollection. If two people freely describe the same event, how similar (across brains) are the neural codes elicited by that event?
In the new study, researchers show that when people watch a movie, specific brain activity patterns can be identified for each scene in the movie. What’s more, each movie scene brain pattern is similar between people while they watch the movie, and similar between people when they speak from memory about the movie in their own words. This goes beyond showing that some part of the brain is “active” (reacting high or low) during some movie scene; the researchers show there is a distinct brain pattern, like a fingerprint, for each movie scene.
“Usually memory experiments use very constrained material like single words or static pictures, so we’re also excited to show that it’s possible to do all of this during a much more realistic experience — watching an hour-long movie and talking freely about it for many minutes,” says co-lead author Janice Chen, a postdoctoral research in Princeton’s Neuroscience Institute.
The researchers found these shared activity patterns during recall in higher level regions of the brain, which appear to recieve and combine information from lower levels. In these high level regions, information seems to be more abstract. For example, whether you watch the scene where Sherlock is meeting Watson for the first time in the BBC TV series “Sherlock” or you speak about it from memory, the researchers found similar brain activity pattern that is unique to this event.
“The function of these high-level regions has been controversial for a long time; they are very active when people are resting, daydreaming, remembering their personal past, imagining the future, during internally focused thoughts, evaluating social situations and a whole lot more other types of tasks that psychologists have come up with,” Chen says. “The notion that they contain specific activity codes for specific scenes/situations might be able to unite many of the other proposals.”
When people have this shared experience, they have shared memories too — the memory is a modified version of the original experience, and it changes in the same way across different people.
“We feel our memories are unique, but there is a lot in common between us in how we see and remember the world, even at the level of these brain activity patterns that we measure at the scale of millimeters,” Chen says. “I think this is no accident: having a common framework for remembering makes it easier to communicate our memories to others, and that’s a powerful thing that human beings can do. If I have a real experience, finding my way to the train station, for example, I can tell you about it and then you don’t have to go through the hassle yourself. You can take advantage of what I learned — my memory communicated to you — and get to the train station, perhaps even getting there more efficiently than I did. In a way, you used my brain to process information from the world, taking a shortcut to acquiring knowledge.”
Source: John Cramer – Princeton University
Image Source: NeuroscienceNews.com image is in the public domain.
Original Research: Abstract for “Shared memories reveal shared structure in neural activity across individuals” by Janice Chen, Yuan Chang Leong, Christopher J Honey, Chung H Yong, Kenneth A Norman & Uri Hasson in Nature Neuroscience. Published online December 5 2016 doi:10.1038/nn.4450
[cbtabs][cbtab title=”MLA”]Princeton University. “Using ‘Sherlock’ to Reveal How Shared Experiences Shape Our Memories.” NeuroscienceNews. NeuroscienceNews, 4 December 2016.
<https://neurosciencenews.com/experience-memory-sherlock-5695/>.[/cbtab][cbtab title=”APA”]Princeton University. (2016, December 4). Using ‘Sherlock’ to Reveal How Shared Experiences Shape Our Memories. NeuroscienceNews. Retrieved December 4, 2016 from https://neurosciencenews.com/experience-memory-sherlock-5695/[/cbtab][cbtab title=”Chicago”]Princeton University. “Using ‘Sherlock’ to Reveal How Shared Experiences Shape Our Memories.” https://neurosciencenews.com/experience-memory-sherlock-5695/ (accessed December 4, 2016).[/cbtab][/cbtabs]
Abstract
Shared memories reveal shared structure in neural activity across individuals
Our lives revolve around sharing experiences and memories with others. When different people recount the same events, how similar are their underlying neural representations? Participants viewed a 50-min movie, then verbally described the events during functional MRI, producing unguided detailed descriptions lasting up to 40 min. As each person spoke, event-specific spatial patterns were reinstated in default-network, medial-temporal, and high-level visual areas. Individual event patterns were both highly discriminable from one another and similar among people, suggesting consistent spatial organization. In many high-order areas, patterns were more similar between people recalling the same event than between recall and perception, indicating systematic reshaping of percept into memory. These results reveal the existence of a common spatial organization for memories in high-level cortical areas, where encoded information is largely abstracted beyond sensory constraints, and that neural patterns during perception are altered systematically across people into shared memory representations for real-life events.
“Shared memories reveal shared structure in neural activity across individuals” by Janice Chen, Yuan Chang Leong, Christopher J Honey, Chung H Yong, Kenneth A Norman & Uri Hasson in Nature Neuroscience. Published online December 5 2016 doi:10.1038/nn.4450
