Striatum
A structure deep in the middle of the brain that helps start and smooth movement and, using dopamine signals, drives wanting, choosing and habits.
The striatum sits under the brain's outer layer, near its centre. It's the largest part of the basal ganglia, a set of deep structures that help start and smooth out movement; that's why losing its dopamine supply in Parkinson's disease makes moving hard. Evidence: solid It receives dopamine from the VTA and its neighbour, the substantia nigra, and helps weigh what's worth going after. Parts of it you may see named are the caudate, the putamen and the nucleus accumbens. Evidence: solid
It's busy when you want something, not only when you get it. Evidence: decent In a choice game, people picked unfamiliar options more often even when they paid nothing extra, and activity in the striatum tracked that pull. Evidence: decent Its upper part is also central to turning repeated actions into habits, shown mostly in animals. Evidence: decent
Why it matters
It's likely part of the "I can't help reaching for it" pull too: the phone, the second drink. That part is an educated guess. Evidence: worth trying Knowing that wanting and enjoying are different jobs helps explain why you keep doing things you don't much enjoy. Evidence: decent