Washington, February 7 : A brain region that gets activated by reward has been found to drive drug-seeking behaviour in rats, say researchers.

Barry Everitt and David Belin of the Department of Experimental Psychology, University of Cambridge, demonstrated the function of the circuitry by selectively switching off drug-seeking in the animals.

The researchers said that their findings show the key role of the brain region called the striatum.

During the study, the researchers first trained rats to press a lever to obtain cocaine, which also activated a signal light. They manipulated the schedule of cocaine-receiving and lever-pressing so that it would induce compulsive lever-pressing in the rats to obtain cocaine.

The researchers found that, when they used surgery and drugs to sever the functional connection between the two striatal regions, the result was decreased drug-seeking behaviour in rats, compared with rats in which the disconnection was not made.

In another experiment, the researchers showed that the "disconnected" rats did not show reduced ability to acquire such training responses.

Both normal and disconnected rats could learn to pull a chain to receive a sugar-water reward so long as the activity was continuously reinforced.

"The results of the present study demonstrate that intrastriatal connectivity is a key aspect of the functional organization of the striatum and also a critically important component of the complex neural mechanisms involved in the development of drug addiction," the researchers concluded.

The study has been published in the journal Neuron.

ANI