Dopamine shown to induce both desire and dread
July 9, 2008 | Source: KurzweilAI
University of Michigan researchers have found that dopamine, the neurotransmitter associated with motivation and positive rewards, can also promote negative feeling like fear and dread.
The researchers had previously found that desire and dread functions were anatomically close together in the nucleus accumbens (a tiny section of the brain–one-fifth of an inch long–associated with desire and reward). In their new research, they found that the effect of dopamine depended on where it was concentrated in the nucleus accumbens. Injections to the front of the nucleus accumbens caused rats to eat three times as much food as normal, but injections to the back caused them to display fearful behavior normally shown in response to a predator.
It was previously assumed that fear and desire came from different neurotransmitters, but the new study shows that anatomy alone can determine a single neurotransmitter’s role.
The finding may help explain why dopamine dysfunction is implicated not only in drug addiction, which involves excessive desire, but in schizophrenia and some phobias, which involve excessive fear.
