Image via WikipediaNueroscience is discovering the relationship between addiction and brain's reward system. In general human's are very susceptible to the anticipation of rewards. There is lot more in common between gambling,sex, good food, chocolate and other pleasurable activities then we thought originally. They all stimulate the pleasure center of the human brain. Excessive indulgence into pleasurable activities is the leading cause of addiction.Here is a complete article on Behavioral' Addictions:Do They Exist?
A small excerpts from the article:
Aided by brain imaging advances, scientists are looking for evidence that compulsive nondrug behaviors lead to long-term changes in reward circuitry
People toss around the term "addiction" to describe someone's relationship to a job, a boyfriend, or a computer. But scientists have traditionally confined their use of the term to substances--namely alcohol and other drugs--that clearly foster physical dependence in the user.
That's changing, however. New knowledge about the brain's reward system, much gained by superrefined brain scan technology, suggests that as far as the brain is concerned, a reward's a reward, regardless of whether it comes from a chemical or an experience. And where there's a reward, there's the risk of the vulnerable brain getting trapped in a compulsion.
"Over the past 6 months, more and more people have been thinking that, contrary to earlier views,there is commonality between substance addictions and other compulsions," says Alan Leshner, head of the National Institute on Drug Abuse (NIDA) and incoming executive officer of the American Association for the Advancement of Science, publisher of Science.
Just where to draw the line is not yet clear. The unsettled state of definitions is reflected in psychiatry's bible, the Diagnostic and Statistical Manual IV. Addictions, obsessions, and compulsions--all related to loss of voluntary control and getting trapped in repetitious, self- defeating behavior--are scattered around under "substance-related disorders," "eating disorders," "sexual and gender identity disorders," "anxiety disorders," and "impulse- control disorders not elsewhere classified." In that last grab-bag are compulsive gambling, kleptomania, fire-setting, hair-pulling, and "intermittent explosive disorder."
Addiction used to be defined as dependence on a drug as evidenced by craving, increased tolerance, and withdrawal. But even some seemingly classical addictions don't follow that pattern. Cocaine, for example, is highly addictive but causes little withdrawal. And a person who gets hooked on morphine while in the hospital may stop taking the drug without developing an obsession with it.
Now many researchers are moving toward a definition of addiction based more on behavior, and they are starting to look at whether brain activity and biochemistry are affected the same way in "behavioral" addictions as they are by substance abuse. One who endorses this perspective is psychologist Howard Shaffer, who heads the Division on Addictions at Harvard. "I had great difficulty with my own colleagues when I suggested that a lot of addiction is the result of experience ... repetitive, high-emotion, high-frequency experience," he says. But it's become clear that neuroadaptation--that is, changes in neural circuitry that help perpetuate the behavior--occurs even in the absence of drug-taking, he says.
The experts are fond of saying that addiction occurs when a habit "hijacks" brain circuits that evolved to reward survival- enhancing behavior such as eating and sex. "It stands to reason if you can derange these circuits with pharmacology, you can do it with natural rewards too," observes Stanford University psychologist Brian Knutson. Thus, drugs are no longer at the heart of the matter. "What is coming up fast as being the central core issue ... is continued engagement in self-destructive behavior despite adverse consequences," says Steven Grant of NIDA.
Not everybody is on board with this open-ended definition. For one thing, says longtime addiction researcher Roy Wise of NIDA, drugs are far more powerful than any "natural" pleasure when it comes to the amounts of dopamine released. Nonetheless, behavioral resemblances to addiction are getting increasing notice.
The complete articel is at
http://www-psych.stanford.edu/~span/Press/bk1101press.html
Finally the part of the brain that is most active in this is called hypothalamus that sits right below neocortex within the brain. Here is a short movie that describes the role of Hypothalamus and its realtionship with the brains'reward center.
What about learning? It has its own rewards that means it also affects the brain's reward system. It could be addictive.
Does that mean teachers are encouraging an addictive activity??
1 comment:
As you know the hypothalamus is not necessary for the fundamental reflexive elemants of consummatory behaviour. For example, classical research in cats with midbrain transections below hypothalamus showed cats could still perform complete responses, such as chewing, swallowing, piloerection. However, when the transection above hypothalamus did the responses look like integrated, motivated behaviour. Thus, the hypothalamus appeared to coordinate and sequence motivated responses, as well as their correlated autonomic responses. This circuitry is now known to descend from the hypothalamus to the midbrain and then to integrative centers in the brainstem and spinal cord.
Structures above the hypothalamus - neocortex and limbic system - modulate behaviour. For instance, stimulation of the amygdala inhibits the rage elicited by stimulation of yhe hypothalamus. Such descending influences are learned, including food responces, conditioned food aversion etc. Inhibition of motivation is not restricted to the neocortex and lymbic structures, for example, inhibitory mechanisms of food intake apparentely are located in the paraventricular nucleus and ventromedial region of the hypothalamus.
To summarize my report, i want to emphasize that the control of motivated behaviour occurs at several distinct and interactive levels of the CNS, i guess, in a hierarchical manner.
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