Cocaine produces hyperactive effects on brain, similar to those on body
The powerful euphoric stimulant – cocaine, also known by street names “crack,” “coke” and “snow” – affects the brain in a way quite similar to its external effects on the body, new research has shown. According to a study published in Cell Reports, the burst of hyperactivity and energy provided by cocaine is a highly accurate reflection of what goes on inside the user’s brain.
Dopamine, the neurotransmitter regulating emotion and movement, is released by neurons that are rapidly fired by a network of brain circuits. This network was mapped out by researchers who were also able to explain why long-term use of cocaine leads to increased tolerance and desensitisation.
The researchers followed electrical activity in the brains of rats “high” on cocaine by using tracer molecules. It was found that the activation of the ventral subiculum and the flared released of dopamine was relayed by a group of neurons in the extended amygdala. The ventral subiculum is the brain’s addiction center, while the extended amygdale is the learning and motivation centre in the brain.
The increased activation of a key part of the extended amygdala produces a long-lasting increase in transmission of signals that fire dopamine release, leading to desensitisation. Some of the long-term effects on motivation and behaviour due to prolonged use of the drug can be explained by changes in the amygdala.
Francois Georges of Bordeaux University in France and senior author on the study, said, “We show that the ventral subiculum recruits the bed nucleus of the stria terminalis (key part of the extended amygdala) to drive a persistent hyperactivity of dopamine neurons and control cocaine-induced activity,” reports Eurekalert.
Similarities in the brain activity between anaesthetised rats and rats exposed to the drug also showed the possibility of changing neurons that produce dopamine to change their response to stimuli.
The research holds potential to better study brain circuits involved in drug addiction as well as the perception of natural rewards such as those involved in exercise or food.
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