Evidence indicates that prior use of some drugs impairs the brain's ability to forge new connections between neurons in response to new experiences.
Scientists took a bunch of rats and gave some of them either amphetamine or cocaine for twenty days, while giving the others a saline solution for twenty days.
When the twenty days were up, half of the rats were moved from ordinary laboratory cages to fancy new cages equipped with all kinds of bridges, ramps, tunnels, and other toys.
After three and half months the scientists examined all of the rats brains.
They discovered that the saline solution rats that were moved to the new cages had a greater number of neuronal connections than all the other rats, including the drugged rats in the new cages.
These findings may aid in explaining some of the behavioral and cognitiveimpairments viewed in people who are addicted to drugs.