( a precise map of the brain's structure...)Pleasure and pain: Study shows brain's 'pleasure chemical' is involved in response to pain too

The volunteers answered questions from two standardized questionnaires repeatedly both in a control (no pain) state and when their jaw muscles were being injected with harmless salt water in order to cause pain. The questionnaires measure pain and emotion in a standardized way, so that ratings can be compared over time. None of the participants had a history of medical or psychiatric illness, nor of drug addiction or dependence. The 7 female volunteers were not taking birth control pills and were scanned at the same point in their menstrual cycles.

In addition to the differences in dopamine receptor activation in certain areas of the brain across all the participants, the scans also revealed differences between individuals in the level of their dopamine response and their self-rated pain and emotional response. This kind of variation may help explain the major variation between individuals who are exposed to addictive drugs ?some become addicted to the pleasures of the "high" the drugs cause, while others do not.

"Variations in risk for drug abuse after initial exposures could be mediated by individual differences in the response of this neurotransmitter system to various forms of stress, with pain being itself a physical and emotional stressor," write the authors, led by David J. Scott, Ph.D., a graduate student at MBNI. "The dopamine system in the ventral basal ganglia may represent an important point of interaction between the neurobiologies of emotion, reward and pain regulation.

The new findings build on previous pain research by Zubieta and his team, which has shown individual variation in the rating of pain, and has visualized the brain's own painkiller system responding to pain and even to the giving of a "placebo" painkiller medication.

Now, the team is working to examine the ho
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Source:University of Michigan Health System