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The Neurobiology of Drug Addiction

4: Activation of the reward pathway by an electrical stimulus

Activation of the reward pathway

The discovery of the reward pathway was achieved with the help of animals such as rats. Rats were trained to press a lever for a tiny electrical jolt to certain parts of the brain. Show that when an electrode is placed in the nucleus accumbens, the rat keeps pressing the lever to receive the small electrical stimulus because it feels pleasurable. This rewarding feeling is also called positive reinforcement. Point to an area of the brain close to the nucleus accumbens. Tell the audience that when the electrode is placed there, the rat will not press the lever for the electrical stimulus because stimulating neurons in a nearby area that does not connect with the nucleus accumbens does not activate the reward pathway. The importance of the neurotransmitter dopamine in the motivational aspects of reinforcing pleasurable behaviors has been determined in these experiments because scientists can measure an increased release of dopamine in the reward pathway either after the rat receives the reward or in expectation of its immediate arrival. And, if the dopamine release is prevented (either with a drug or by destroying the pathway), the rat won't press the bar for the electrical jolt. So, with the help of the rats, scientists figured out the specific brain areas as well as the neurochemicals involved in motivation and reward.

This page was last updated January 2007

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NIDA. (2007, January 2). The Neurobiology of Drug Addiction. Retrieved from https://www.drugabuse.gov/neurobiology-drug-addiction

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