October 30, 2013
Human Addictions May Be Solved Via Innovative Rat Gambling Study
Alan McStravick for redOrbit.com - Your Universe Online
Researchers at the University of British Columbia have identified brain processes that may be linked to compulsive gambling, and they did so by creating an interesting and inventive study tool: a rat casino.
This study is the first of its kind in North America to model a slot machine-style gambling tool using rats. It is also the first study to successfully show how problem gambling behaviors can be treated with pharmaceuticals meant to block the dopamine D4 receptors. Their findings have been published in the journal Biological Psychiatry.
Paul Cocker, lead author on the study and PhD student in the Department of Psychology at UBC, said, “More work is needed, but these findings offer new hope for the treatment of gambling addiction, which is a growing public health concern.” Cocker continued, “This study sheds important new light on the brain processes involved with gambling and gambling addictions.”
The 16-month study employed 32 rat subjects that were taught to respond to a series of three flashing lights before choosing between two levers. A win was indicated when all lights would illuminate. The rat would know they lost when either zero lights illuminated or only one or two lights lit up.
When the rat was presented with a win, a “cash-out” lever could be depressed, rewarding the rat with 10 sugar pellets. However, if a loss occurred, the rat was prohibited from playing again for 10 seconds. If the rat opted to “roll again” rather than “cashing out” for their winnings, a new trial would start, but no sugar pellets would be dispensed.
One action that intrigued the team was the rats’ tendency to opt for a “cash-out” when two of the three lights were illuminated. This, the researchers believe, shows how rats, like humans, are susceptible to the near-miss effect. It was only after administering drugs meant to block the D4 receptors that researchers were able to successfully reduce the rats' choice of the “cash-out” lever on trials where they had not won.
A near-miss, where one comes very close to a winning combination, is a common cognitive bias and is considered to be important in the eventual development of pathological gambling problems. The team notes the high frequency of near-misses inherent in slot machine gambling, especially when compared to other gambling games, may be the reason that slot machines are such a particularly addictive form of gambling.
Other earlier studies had focused on D4 receptors, which have been linked to a wide variety of behavioral disorders. Use of the D4 blocker drug in human tests had appeared to have no effect. However, when administered to the rat subjects, it was clear there was a reduction in the levels of the behaviors associated with problem gambling among the cohort.
“Pathological gambling is increasingly seen as a behavioral addiction similar to drug or alcohol addiction, but we know comparatively little about how to treat problem gambling,” says Cocker. “Our study is the first to show that by blocking these receptors we might be able to reduce the rewarding aspects of near-misses that appear to be important in gambling.”
The team cautions, however, that further research is required before the drugs used in the study should be considered as a viable pharmaceutical treatment for pathological gambling in humans.