Just so we’re clear
That idea that there is limited memory space in the brain, and that by knowing or learning certain facts you are “taking up” space that could be devoted to other things
Is a myth. Brains do not, as far as we can tell, run out of storage space. Memory problems in humans are a problem of incorrectly encoding/storing info, or simply being unable to retrieve that which has already been stored.
See here: http://io9.com/if-your-brain-were-a-computer-how-much-storage-space-w-509687776