Using cocaine once is enough to rewire the brain and cause addiction, according to new research.
A new study, conducted on mice, shows cocaine speedily rewires high-level brain circuits that support learning, memory and decision-making.
The research, from UC Berkeley and UCSF, sheds light on the frontal brain's role in drug-seeking behavior and may be key to tackling addiction.
Researchers found that, after just one dose of cocaine, the rodents showed fast and robust growth of dendritic spines, which are tiny, twig like structures that connect neurons and form the nodes of the brain's circuit wiring.
Assistant professor of psychology and neuroscience at UC Berkeley, Linda Wilbrecht, said their images provide clear evidence that cocaine induces rapid gains in new spines.
"The more spines the mice gain, the more they show they learned about the drug," she said.
For mice "learning about the drug" can mean seeking it out to the exclusion of meeting other needs, which may explain how addiction in humans can override other considerations that are necessary for a balanced life.
"The downside is, you might be learning too well about drugs at the expense of other things," Wilbrecht said.
Using a technology known as 2-photon laser scanning microscopy, researchers made images of nerve cell connections in the frontal cortices of live mice before and after the mice received their first dose of cocaine and, within just two hours, observed the formation of new dendritic spines.
"The number of new, robust spines gained correlated with how much the individual mice learned to prefer the context in which they received the drug," Wilbrecht said.
The findings provide clues to behavioral and environmental factors in drug addiction.