Recalling memories is a straightforward task for humans – a simple act of closing our eyes often brings a flood of moments rushing back. However, beneath this seemingly effortless experience, there exist intricate processess. Dartmouth College researchers have identified the complicated neurological systems that regulate how the human brain stores memories. The findings revealed a "neural coding mechanism" in the brain that allows information to be transferred between perception and memory regions. "We found that memory-related brain areas encode the world like a 'photographic negative' in space," said Adam Steel, the co-lead author, in an official release. "And that ‘negative’ is part of the mechanics that move information in and out of memory, and between perceptual and memory systems," added Steel, who is a postdoctoral researcher in the Department of Psychological and Brain Sciences and fellow at the Neukom Institute for Computational Science at Dartmouth. Examining brain activity The researchers undertook a series of tests to learn more about how the brain encodes and recalls detailed memories. The team used functional magnetic resonance imaging (fMRI) to capture brain activity in study participants assessed on perception and memory. Via these experiments, the team pinpointed a "push-pull coding mechanism" that regulates the interaction between perceptual and memory areas. “The results showed that when light hits the retina, visual areas of the brain respond by increasing their activity to represent the pattern of light. Memory areas of the brain also respond to visual stimulation, but, unlike visual areas, their neural activity decreases when processing the same visual pattern,” explained the release. The key results from the experiments The authors were able to draw three key findings from their extensive observations. Firstly, researchers revealed that brain memory systems retain a visual coding basis. Second, this visual code is displayed “upside-down” in memory systems, suggesting a distinct brain processing property. "When you see something in your visual field, neurons in the visual cortex are driving while those in the memory system are quieted," said senior author Caroline Robertson, an assistant professor of psychological and brain sciences at Dartmouth. Lastly, the link between perceptual and memory systems flips during memory recall, underscoring the complicated dynamics at work. "If you close your eyes and remember that visual stimuli in the same space, you'll flip the relationship: your memory system will be driving, suppressing the neurons in perceptual regions," added Robertson, in the The next step for the study team is to look at how this push-pull dynamic between perception and memory might help us comprehend cognitive processes in diseases like Alzheimer's. The finding opens up new paths for studying the intricate interplay between perception and memory, perhaps leading to advances in neuroscience and therapeutic research. The findings were published in the journal