well med schools cover upper division biology (cell bio, genetics, biochemistry, a&p, neuro/psych, immunology, virology, histology, etc, etc) but in much greater detail.
things ive heard:
taking biochemistry in ugrad usually helps a lot because of how quickly it is covered in med school..
taking genetics can be useful for the same reason
DONT take a&p, as it's likely nothing compared to med school a&p,
then from there on take w/e interests you, but i also hear neuro is one of the tougher topics so you might want to take a few courses if the subject interests you.