Rats repeatedly exposed to cocaine and then withdrawn from it exhibit neural changes in the lateral amygdala, a part of the brain involved in responding to pleasurable and aversive stimuli. Such changes may mediate the negative emotional effects that accompany drug withdrawal, say the researchers who documented the effect in a recent study. Dr. Vadim Bolshakov and colleagues at Harvard Medical School have shown that longterm potentiation (LTP), a process underlying learning and memory, occurs in the lateral amygdala when cocaine-exposed rats no longer have access to the drug. They found a clear link between LTP and enhanced levels of the neurotransmitter glutamate in the lateral amygdala and signs of withdrawal in the rats. The findings suggest that amygdala circuits might contribute to drug modulation of motivational states and influence addictive behaviors.
European Journal of Neuroscience 23(1):239-250, 2006. [Abstract]