If the fringe theory of microtubules storing memories in quantum states in the human brain is correct, there is a critical magnetic field past which you'd forget everything... including the things you learned in infancy, like how to hold your head up, crawl, talk, etc.

I suspect that critical field would be somewhere near 1000 Tesla, as the critical temperature is well above 2000k. (The theory is that memories are stored in a topological superconductor which would denature well before the critical temperature was reached)

This type of reversion to infancy is the stuff of nightmares.