One hypothesis for how knowledge is organized in the brain proposes that representations of the things we know are optimally connected to other parts of the brain that are necessary for processing that information.

“For example,” Caramazza said, “knowledge of something I can see will be organized in a part of my brain that is easily connected with the visual system. But what about color in the blind? It cannot be represented in an area that’s connected to visual processing. Because they learn about it through language, it will be organized in an area that is especially well-connected with language processing. So if the question is where does a blind person store a representation of a rainbow in their brain, they store it in the same area where a sighted person would store a representation of a concept like justice or virtue.”

To see that process in action, Caramazza and his colleagues recruited both blind and sighted volunteers and used fMRI scanners to track activity in their brains as they performed various tasks, including answering questions about rainbows and colors.

“We found that, in the congenitally blind, the neural responses for red were in the same areas as the neural responses for justice,” he said. “The abstractness of something like red in the blind is the same as the abstractness of virtue for the sighted, and in both cases that information is represented in a part of the brain where information is obtained through linguistic processes.”

https://news.harvard.edu/gazette/story/2019/02/making-sense-of-how-the-blind-see-color/