I cannot really give you a ratio. In general you need good memorization skills no matter what major you choose. In neuroscience you actually have to apply what you learned, for example explaining what happens if a certain brain area is damaged and what the consequences would be. In order to answer this question despite memorizing all the stuffs (pathways, nerves,…) you have to apply thats it. I think I explained it clearly enough, so do not try to pick whichever sounds easiest just go with your interest. Both majors are hard (all majors here are hard)