So I'm gonna give a mouse now, sugar versus water. Normal mouse will drink from the sugar, sugar, sugar, sugar, very little from the water. Knock out the sweet receptors, eliminate them. Mouse can no longer tell them apart and they will drink from both. But if I keep the mouse in that cage for the next 48 hours, something extraordinary happens when I come 48 hours later and I see what the mouse is leaking or drinking from.

That mouse is drinking almost exclusively from the sugar bottle. How could this be? He cannot taste it, doesn't have sweet receptors. During those 48 hours, the mouse learn that there is something in that bottle that makes me feel good.