As we move around the world, what we see is seamlessly integrated into our memory of the larger space environment. How does the brain accomplish this feat? A new study from Dartmouth College finds that three regions of the brain in the posterior cerebral cortex, which researchers call “place memory areas”, form a link between the brain’s perception and memory systems. The results are published in Nature communications.
“As we navigate our surroundings, the information enters the visual cortex and sort of ends up knowing where we are – the question is where this transformation into spatial knowledge occurs. We think the place memory areas could be where this is happening ”. explains lead author Adam Steel, a Neukom Fellow in the Psychology and Brain Sciences Department at Robertson Lab in Dartmouth. “When you look at the location of the areas of the brain that process visual scenes and those that process spatial memories, these areas of place memory literally form a bridge between the two systems. Each of the brain areas involved in visual processing is associated with a place. -memory counterpart. “
For the study, an innovative methodology was used. Participants were asked to perceive and remember places they had been in the real world during Functional Magnetic Resonance Imaging (fMRI), which produced high-resolution, specific maps of brain activity. a subject. Previous studies of scene perception and memory often used stimuli that participants knew but had never visited, such as famous landmarks, and pooled data on many topics. By mapping the brain activity of individual participants using real-world places they had been, the researchers were able to unravel the brain’s fine organization.
In one experiment, 14 participants provided a list of people they knew personally and places they visited in real life (for example, their father or their childhood home). Then, while in the fMRI scanner, the participants imagined that they were seeing these people or visiting these places. Comparison of brain activity between people and places revealed areas of place memory. Importantly, when the researchers compared these newly identified regions to areas of the brain that process visual scenes, the new regions overlapped but were distinct.
“We were surprised,” says Steel, “because the classic understanding is that the areas of the brain that perceive should be the same areas that are engaged during memory recall.”
In another experiment, the team investigated whether areas of place memory were involved in recognizing familiar places. During the fMRI scan, participants received panoramic images of familiar and unfamiliar real-world locations uploaded from Google Street View. When the researchers looked at neural activity, they found that areas of place memory were more active when pictures of familiar places were shown. Areas of scene perception did not show the same improvement when viewing familiar locations. This suggests that place memory areas play an important role in recognizing familiar places.
“Our results help explain how a generic image of a clock tower becomes an image we recognize, like the Baker-Berry Library tower here on the Dartmouth campus,” says Steel.
“It’s exciting to discover a whole new set of brain areas,” says lead author Caroline Robertson, assistant professor of psychological and brain sciences at Dartmouth. “Learning how the mind is organized is central to the quest to understand what makes us human.”
“The place-memory network provides a new framework for understanding the neural processes that drive memory-guided visual behaviors, including navigation,” says Robertson.
The research team is currently using virtual reality technology to explore how representations in memory-of-place areas change as people become familiar with new environments.
Madeline Billings at Dartmouth and Edward Silson at the University of Edinburgh were also co-authors of the study.
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