Wanting vs. Liking

Kent Berridge's 1989 dopamine-depletion experiments on rats revealed a dissociation that overturned popular neuroscience: animals stripped of dopamine still liked sugar placed on their tongues but would no longer pursue it. The motivational drive had vanished; the hedonic response was intact. This established that the mesolimbic dopamine pathway generates wanting — incentive salience, the pull toward a reward — while opioid and endocannabinoid systems in the nucleus accumbens shell and ventral pallidum generate liking, the felt pleasure of actually experiencing the reward. Under ordinary conditions the two systems operate in such tight concert that common sense never needed to distinguish them. Desire and pleasure felt like the same thing. Berridge's contribution was finding the conditions under which the coupling breaks — and showing that the uncoupling is the neural signature of addiction.