Compared with the controls, the pathological gamblers showed a lower level of activity in the ventral striatum, the dopamine-producing brain region that provides the pleasure in winning, suggesting gamblers remain unsatisfied even when winning. The scans also showed decreased activation of the ventrolateral prefrontal cortex -- the brain's "superego," which keeps people from acting impulsively.
Mick Jagger would understand. Gamblers "just can't get no satisfaction".
In the study, the brains of 12 compulsive gamblers and 12 non-gamblers were monitored using functional magnetic resonance imaging (fMRI) while they played a simple card guessing game.
If dopamine levels could be boosted in the brains of compulsive gamblers they might not feel as great a need to gamble. However, another group found in results they published in May 2004 that dopamine release increases in one area of the brain while decreasing in other areas when an unpredictable monetary award arrives.
Zald and his colleagues used positron emission topography (PET scanners) to view brain activity in nine human research subjects who had been injected with a chemical that binds to dopamine receptors in the brain, but is less able to bind when the brain is releasing dopamine. A decrease in binding to the receptors is associated with an increase in dopamine release, while an increase in binding indicates reduced release of dopamine. This technique allows researchers to study the strength and location of dopamine release more precisely than has previously been possible.
The team studied the subjects under three different scenarios. Under the first scenario, the subject selected one of four cards and knew a monetary reward of $1 was possible but did not know when it would occur. During the second scenario, subjects knew they would receive a reward with every fourth card they selected. Under the third scenario, subjects chose cards but did not receive or expect any rewards.
Zald and his team found that over the course of the experiment, dopamine transmission increased more in one part of the brain in the unpredictable first scenario, while showing decreases in neighboring regions. In contrast, the receipt of a reward under the predictable second scenario did not result in either significant increases or decreases in dopamine transmission.
The most effective treatments for gambling and drug addictions are going to have to involve manipulation of pleasure regions of the brain. Well, that is quite the Rubicon to cross. Once pleasure centers are effectively rewired to treat addictions rewiring for other purposes will not be too far behind. Imagine the possibilities for individual and group manipulation if the brain regions for pleasure and pain can be reorganized to any significant extent.
Another interesting consequence of the ability to conduct experiments that show neurological differences between addicts and normal people is that this will eventually lead to very objective methods for diagnosing addictions. Junior just got busted for using. Oh my, is Junior a crackhead? Or is he just recreationally using cocaine on occasion? Mom and dad will demand a brain scan test to find out. Or juvenile courts will require the brain scan. Similar work is bound to lead to effective means by which to reliably diagnose assorted compulsions and preferences. I predict that some day successful lack of response to child pictures while being brain scanned will be a required condition for parole of convicted pedophiles. Also, one can imagine recovering addicts to be required to pass a neurological test for lack of craving for an addictive drug as a condition for parole or to regain custody of children taken away by the state.
|Share |||Randall Parker, 2005 January 11 07:27 PM Brain Addiction|