June 3, 2004
Many of us know it's exciting to place a bet on a horse like possible Triple Crown winner Smarty Jones. As this ScienCentral News video reports, researchers are looking at what happens in our brains when we place a bet or buy lottery tickets.
Place Your Bets
What goes on in the brain of a gambler? Researchers have found that the feeling of excitement might be linked to the release in the brain of dopamine, a chemical associated with the pleasure people get from eating, sex, and drugs.
David Zald, psychology professor at Vanderbilt University, and his team used positron emission topography (PET) to observe the brain activity in nine people who were given gambling-like activities to perform. "The main thing that we wanted to see, first off, was whether we could image dopamine release in humans while they were winning money," says Zald. "Our key hypothesis was that we would indeed be able to see dopamine release while people are winning money."
In the first gambling-like activity, the person chose one of four cards, knowing a reward of one dollar was possible, but not knowing when; in other words, the reward was unpredictable. In the second activity, the people knew they would get the reward with every fourth card chosen, so the reward was predictable. In the third activity, people chose cards without expecting to get a reward at all.
Zald and his colleagues found that in eight out of the nine subjects, during the unpredictable first activity, dopamine transmission increased more in the caudate nucleus, a C-shaped region in the brain that is associated with the desire to win a reward. But during the predictable second activity, dopamine transmission neither increased nor decreased. "What was most striking is the greatest increase in dopamine release happened during the unpredictable condition," explains Zald. "But during that same unpredictable condition we also saw areas where there was decreased dopamine release. So they actually released less dopamine in certain areas than when [the situation] was highly predictable or even when they weren't winning any money." Zald says this indicates a more complex reaction in the brain to winning and losing.
So just the possibility of winning can keep some people in the game. "It's not just winning the money that matters, it's the context in which you win it," explains Zald. "Whether it was predictable or unpredictable makes a huge difference. The anticipation or the expectation appears to make a large difference."
Because dopamine is associated with addiction, Zald points out that "the natural production and release of dopamine during the sort of condition of where you're winning or losing money very much mimics the effects of drugs of abuse like cocaine or amphetamines. It's almost certainly at a lower level most of the time, but in fact, people are releasing dopamine and that is changing based on what's happening in terms of winning and losing."
Next, Zald will study at an even more unpredictable activity: a roulette-like wheel. But for now, to all who are betting on the upcoming Belmont Stakes, Zald says, "Good luck, and it's a better way to get your dopamine system going then taking drugs."
This research appeared in the April 28th 2004 issue of the Journal of Neuroscience and was funded by Unilever Research and the National Science Foundation.