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At first the rat wandered randomly. But once it accidentally hit the switch
for the first time, its behavior changed. It started pushing the switch more
and more often. Over time it became a junkie, endlessly jolting itself in a
manic loop of self-stimulation.
Olds' experiments established the idea of the brain's reward center .
When activated, the reward center spurts out a dollop of the brain chemi-
cal dopamine. Ordinarily, the reward center generates dopamine in re-
sponse to everyday stimuli, like a bite of tasty food, winning money, or a
look at an attractive mate. Olds' brain wire worked by forcing this natural
response into overdrive.
In the 1960s, researchers started investigating this effect in humans.
The first was Robert Heath, chairman of the Department of Psychiatry
and Neurology at Tulane University in New Orleans. In his most infamous
study, Heath attempted to “treat” a homosexual using a brain wire. The
young man, known by the code name B-19, had grown up in an abusive
household, had few friends, and lived on the edge of suicide. Heath wired
him up, and handed him the switch. In Heath's words, “B-19 stimulated
himself to a point that, both behaviorally and introspectively, he was ex-
periencing an almost overwhelming euphoria and elation and had to be
disconnected, despite his vigorous protests.”
Olds' and Health's experiments cemented the dopamine theory of
motivation: motivation is driven by a pursuit of pleasure, and pleasure's
messenger is dopamine. And this commonsense model stood for many
years.
But then the problems started to appear.
Dopamine Motivation
The first was in the timing of the dopamine flood. Researchers discovered
that the dopamine does not appear at the same time as the reward is re-
ceived, nor does it appear afterward. Rather, the dopamine comes before
the reward.
If dopamine is pleasure, this doesn't make sense. When you go to the
store to buy a steak, you are not having the same experience as when you
are eating the steak. But your brain is still soaked in dopamine, even as
you're browsing the meat aisle in the supermarket.
This strange result opened the field to later studies that tried to under-
stand the real role of dopamine.
In 2009, 61 subjects rated their desire to vacation in various destina-
tions around the globe. Some of them were given L-Dopa, a drug that
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