Synesthesia is a rare and non-pathological condition wherein the stimulation of a certain sense provokes a secondary perception in another. In short, it makes a person hear sounds upon seeing images, see colors upon hearing music or experience taste when certain words and phrases are spoken.

This is believed to be neuroscience’s final frontier. Tiny bubbles will open the blood-brain barrier to sneak drugs into tumours – and we might treat Alzheimer's the same way, reports New Scientist.