Reward Pathways And Drugs

The observation that animals would work in order to receive electrical stimulation to discrete brain areas was first described by Olds and Milner (1954). In this paper, they stated, ''It is clear that electrical stimulation in certain parts of the brain, particularly the septal area, produces acquisition and extinction curves which compare favorably with those produced by conventional primary reward.'' This phenomenon is usually referred to as brain-stimulation reward (BSR), intracranial self-stimulation (ICSS), or intracranial stimulation (ICS).

Most abused substances increase the rate of response (lever pressing) for rewarding ICS, and this has been interpreted as an increase in the reward value of the ICS. Because changes in rate of response could also be a function of the effects of the drug on motor performance, a number of methods have been developed that control for the confounding nonspecific effects of the drugs under study, at least in part. The three most commonly used procedures are phase shifts (Wise et al., 1992), two-level titration (Gardner et al., 1988), and the psychophysical discrete-trial procedure (Kornetsky & Porrino, 1992). Using these threshold methods for determining the sensitivity of an animal to BSR, there is general agreement that most of the commonly abused substances do in fact increase the sensitivity of animals to the rewarding action of the electrical stimulation and this action is independent of any motor effects of the substances.

Brain Blaster

Brain Blaster

Have you ever been envious of people who seem to have no end of clever ideas, who are able to think quickly in any situation, or who seem to have flawless memories? Could it be that they're just born smarter or quicker than the rest of us? Or are there some secrets that they might know that we don't?

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