The classical understanding of brain organization is that the brain's perceptual areas represent the world 'as it is', and the brain's visual cortex represents the external world 'retinolocally', based on how light hits the retina. That's what it means. In contrast, the brain's memory areas are thought to represent information in an abstract form, stripped of details about physical properties. Now, a team of neuroscientists from Dartmouth College and the University of Edinburgh have identified the neural coding mechanisms that allow information to move back and forth between the brain's sensory and memory regions.
Traditional views of brain organization suggest that regions at the top of the cortical hierarchy process internally directed information using abstract, amodal neural codes. Nevertheless, recent reports have described the presence of retinotopic coding at cortical vertices, including the default mode network.What is the functional role of retinal local coding at the apex of the cortical hierarchy? Steel other. We report that retinotopic coding structures interactions between internally oriented (memory) and externally oriented (perception) brain regions. Image credit: Gerd Altmann.
“We now know that brain regions associated with memory encode the world, like a 'photo negative' of the universe,” said Dr. Adam Steele, a researcher at Dartmouth College.
“And that 'negativity' is part of the mechanism that moves information in and out of memory, and between perceptual and memory systems.”
In a series of experiments, participants were tested on perception and memory while their brain activity was recorded using a functional magnetic resonance imaging (fMRI) scanner.
Dr. Steele and his colleagues identified a contralateral push-pull-like coding mechanism that governs the interaction between perceptual and memory areas in the brain.
The results showed that when light hits the retina, the brain's visual cortex responds by increasing activity that represents the pattern of light.
Memory areas of the brain also respond to visual stimuli, but unlike visual areas, processing the same visual pattern reduces neural activity.
“There are three unusual findings in this study,” the researchers said.
“The first is the discovery that visual coding principles are stored in the memory system.”
“The second thing is that this visual code is upside down in our memory system.”
“When you see something in your visual field, neurons in your visual cortex become active and neurons in your memory system quiet down.”
“Third, this relationship is reversed during memory recall.”
“If you close your eyes and recall that visual stimulus in the same space, the relationship is reversed. Your memory system kicks in and suppresses the neurons in your sensory area.”
Dr Ed Shilson, a neuroscientist at the University of Edinburgh, said: “Our findings demonstrate how shared visual information is used by the memory system to bring recalled memories into and out of focus. “This provides a clear example of how this can be done.”
of study Published in today's magazine natural neuroscience.
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A. Steel other. Retinotopic codes structure interactions between perceptual and memory systems. nut neurosi, published online on January 2, 2024. doi: 10.1038/s41593-023-01512-3
Source: www.sci.news
