In a May 30 press release, NIDA announced that scientists
have found that a single use of cocaine can modify neural connections
in the brain, and this may help explain at the cellular level
how occasional drug use can progress into a compulsion.
The researchers from the University of California in San Francisco
report in the May 31 issue of Nature that a single injection
of cocaine induced a long lasting (between 5 and 10 days) increase
in excitatory synaptic transmission in the ventral tegmental
area of the brain in rats and mice. The increase in synaptic
in neural activity involved in learning and memory processes
in many areas of the brain.
"These findings on the impact of cocaine on the memory
and learning circuits of the brain may help explain the switch
from occasional drug useto addiction. This study emphasizes
the dangers of even experimenting with cocaine and other illicit
drugs," says Alan I. Leshner, Ph.D., Director of the National
Institute on Drug Abuse (NIDA).
"The significance of this finding," says lead investigator
Dr. Antonello Bonci, "is that the single dose of cocaine
'usurped' a cellular mechanism involved in a normally adaptive
learning process, which may help to explain cocaine's ability
to take control of incentive-motivational systems in the brain
and produce compulsive drug-seeking behavior."
In addition, the researchers said that the changes that were
observed in the brains of the rats and mice may be important
not just for the early stages of addiction, but also may help
explain the neural basis for relapse, where a single exposure
to cocaine after a period of abstinence can induce renewed