I'm writing a character that receives a major head injury—which leads to part of his brain being taken out. Just enough so he should go blind. Except, he doesn't. Instead, his sight starts getting processed by a different part of his brain. A part that might be thought to be responsible for seemingly psychic phenomena. This leads to him being able to see impressions that are left behind on items & in rooms.
Is there anyone out there that can help me explain that in a scientifically viable manner?
Hi iam. I think you'd have better luck without trying to remove part of your character's brain. Head injury or stroke will do the trick -- especially if it's restricted to the primary visual cortex in the occiptal lobes at the back of the head.
What you're describing here is somewhat similar to the phenomenon of blindsight, which you can google.
The brain is very plastic, but there are limits. As far as I know, there's no one region of the brain that's been definitively linked to "extranormal communications." (Sorry -- I hate the term "psychic.") Some theories have been proposed that involve overactivation or underactivation of the temporal lobes, but the temporal lobes wouldn't likely be able to take on the task of visual processing per se.
Another topic you might want to look up is synesthesia, where signals from one sense sort of "jump the track" to another sensory pathway. Synesthetes report things like being able to hear colour or see sound. Very interesting stuff.
Good luck with your story!
Jen