“Gambling” Rats Could Help with Treatments for Gambling Addiction
The test studied how lab rats reacted to setups in which the choices they made could result in a reward or a loss. Instead of money, they were looking for sugar pellets. The rodents were placed in custom boxes with “response holes”—each opening was associated with the possibility of earning from one to four treats.
When a rat looked into a hole, the movement would break an infa-red light across the opening, signaling a computer with a reward-punishment schedule to assign a pellet win or a “timeout” loss. The rats had 30 minutes to accumulate as many sugar pellets as they could.
The rats quickly learned that openings with three or four treats also posed the highest risk for punishment—a greater number of and longer-lasting timeouts during which they could not seek pellets.
The rodents were able to calculate risk and opted for a number of small wins instead of taking a chance on the riskier jackpots. They learned over time that playing conservatively was the best strategy.
Behavioral neuroscientist Catharine Winstanley, principle investigator of the study, said that lab rats are incredibly smart. “They're capable of solving quite complex paradigms, as we've shown here, the sort of thing that you may argue that 'I can't believe anything other than a human could solve."'
"Having to sit through these very tedious timeouts was very frustrating for them and it lost them time they could be earning reward at another location," Winstanley said. "So they had to learn to avoid those very tempting larger reward options and instead go for smaller reward options that would over time give them maximal gain."
The study also tested how the rats’ responses changed after being given certain drugs to reduce serotonin and dopamine, two brain chemicals that are linked to addictive behavior. When the rats were given a drug that lowers serotonin, their ability to determine the best option was reduced. "They became worse gamblers, if you like,” Winstanley said.
When they were given drugs to drop dopamine levels, their ability to optimize rewards was greatly improved. Winstanley noted that drugs that boost serotonin levels like antidepressants are often used to treat people with a gambling addiction.
The finding parallels an observation of people with Parkinson's disease, some of whom develop a sudden gambling addiction after being treated with drugs to boost diminishing dopamine levels in their brains.
"There's very few effective treatments out there" for gambling addiction, said Winstanley. "This is very much a first step. We're really happy we can see gambling-like behavior in our rats and now we can use this task to really probe the neural and neurochemical basis for gambling disorders."