Are Rats Risk-Averse?

Rats are often studied to determine how humans might behave in a similar situation or react to a medication. Though rats have been known to understand simple reward and punishment responses, it has not been explored whether rats could understand the concept of “playing the odds.” A recent study by Zeeb, Robbins, & Winstanley in 2009 examined whether rats are capable of such behavior and whether altering their brain chemistry to imitate the brain chemistry of human gamblers would change the rats’ decisions.

The study involved 32 rats that were offered four trays (P1-4) to explore for food. Each time the rats “won” they were given one or more sugar pellets. Each time the rats “lost” they were not able to play the game for a specified amount of time depending on the tray chosen. The optimal choice for long-term gain was tray P2, which dispensed 2 sugar pellets and had a moderate waiting time for losses. Tray P1 had the lowest risk and lowest reward, while tray P4 had both the highest potential for reward and longest waiting time.

After the researchers established a week of baseline behavior, the rats were injected with drugs that affected the level of dopamine in the rats’ brains. They were given one of several drugs, such as amphetamine (can increase the level of dopamine in the brain), eticlopride (blocks dopamine receptors), and SKF 81297 (triggers dopamine response by the brain cell).

The researchers found that the rats chose the tray with optimal results associated with a modest gain and moderate punishment, tray P2. Additionally, it was found that with the use of an amphetamine, rats significantly increased their selection of tray P1, which was the least optimal choice with the least punishment but also the least reward. Eticlopride increased the rats’ choice of tray P2, the most optimal choice, while SKF 81297 increased the selection of tray P4, the most risky choice.

The study had several limitations. This study is not a complete picture of human gambling behavior, and the decision-making task presented to the rats is not really a substitute for gambling. The effects of the dopamine did not clearly represent either an avoidance of punishment or attentiveness to rewards, and it was not clear whether the rats were weighing risk and rewards or simply remembering the past results of choosing particular trays.

The research done by Zeeb et al. does indicate that rats are capable of playing the odds and that they show similar risk-averse behavior that humans do. The results also indicate that altering dopamine levels in the brain can impact gambling decisions. Higher levels of dopamine in the brain may influence gamblers to make poor decisions, leading to gambling-related problems.

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