Given the widespread legalization of cannabis for medical and recreational uses, you'd think we'd have a better understanding of how it works. But ask a neuroscientist exactly how cannabinoid compounds like THC and CBD alter our perceptions or lead to potential medical benefits, and you'll soon learn just how little we know.We know that these molecules hijack an ancient signaling system in the brain called the "endocannabinoid" system (translation: the "cannabinoids within"). These somewhat e...