Scientists say they have discovered the neural coding system our brains use to transform images into memories, suggesting we're all visual thinkers deep down.

The long-held belief that our grey matter turns visual signals into a non-visual form of data to encode as memories is likely false, according to a paper by folks at Dartmouth College in the US and published today in Nature Neuroscience. Rather, it seems more like "retinotopic" information, 3D visual information encoded by the brain via the retina, is the base coding mechanism for memories related to visual stimuli.

Think of it as our brains storing actual visual info in memory rather than descriptions that we use to reconstruct a scene on demand. A picture on the wall, not lines of text. Is this a study from the university's Dept of the Bleeding Obvious? You might argue so, or you might argue it's worthwhile research, but in any case that's science: putting aside assumptions, figuring it out for good, and writing it down.

The academics arrived at their conclusions through a trio of functional magnetic resonance imaging (fMRI) experiments in which they scanned the brains of people looking at and recalling specific images. They observed a direct inverse relationship between sensing and memory portions of the brain and where they light up when making or recalling a memory.

"We think that the retinotopic code is used as a means of reading (and writing) visual information into (and out of) memory systems," Adam Steel, a postdoc at Dartmouth's department of psychological and brain sciences and co-author of the work, told The Register. 

In addition to the correlation between areas of brain activity, Steel explained there's an "opponent suppression" dynamic, in which the two sensing and memory areas of the brain show lower activity when the other is being used. This, he said, suggests a central role of retinotopic code in translating between neural systems in the brain. 

When asked to recall an image, activity in mnemonic areas of the brain showed an inverted spike in visually-evoked "population reception fields" that corresponded to the original sensing areas of the brain, suggesting that "retinotopic coding could serve as a shared substrate to scaffold the interaction between perceptual and mnemonic systems," the report posits. 

Of course, that doesn't mean visuals are everything when it comes to memory - semantic and language encoding is done alongside retinotopic data when the brain encodes memory, Steel explained. 

Of course, this can't work in every case given capability and cognitive differences. "[Retinotopic coding] can't be the only system that is used - congenitally blind individuals also have rich memory experiences despite having no visual experience," Steel said. 

Differences may also exist in the brains of people with photographic memories, those with autism, and it's likely image processing capability change as we age as well, Steel said. 

"The mnemonic areas where we see negative visual coding are well aligned with areas impacted by aging and Alzheimer's disease," Steel said, suggesting the discovery, which the team described in their paper as presenting a challenge "to conventional views of brain organization," could someday be used to treat memory diseases, too. ®

https://www.theregister.com//2024/01/02/dartmouth_visua_brain_memory/