Robots Terrify Zebrafish: How Alcohol Affects Fearful Fish

First Posted: Aug 01, 2013 06:58 AM EDT

Robots are terrifying--at least, fish think so. In a new set of experiments, researchers have discovered that fish robots can elicit fear in zebrafish and that this reaction can be modulated by alcohol. The findings could allow researchers to better understand anxiety and other emotions in addition to the substances that alter them.

Although attempting to scare drunk zebrafish with robots may seem like it wouldn't lead to any interesting findings, the researchers were able to learn quite a bit. The scientists first created a robot that mimicked the appearance and movements of the Indian leaf fish, the natural predator of the zebrafish. They then placed the robot and zebrafish in separate components of a three-section tank. One section was left empty. In the end, the scientists found that the control group uniformly avoided the robotic predator, showing a preference for the empty section. In other words, they were terrified to go near the robot.

Knowing that the fish would avoid the predator, the next question became if alcohol would affect the responses of the zebrafish. In theory, it could potentially relax the fish to be a bit calmer around the robotic predator. The researchers exposed separate groups of fish to different doses of ethanol, which has been shown to influence the anxiety-related responses in humans, rodents and some species of fish. It turns out that the drunkest fish didn't bother avoiding the predatory robot.

"These results are further evidence that robots may represent an exciting new approach in evaluating and understanding emotional responses and behavior," said Maurizio Porfiri, one of the researchers, in a news release. "Robots are ideal replacements as independent variables in tests involving social stimuli-they are fully controllable, stimuli can be reproduced precisely each time and robots can never be influenced by the behavior of the test subjects."

The findings have potential for future research on emotional responses. The scientists believe that zebrafish could be a suitable replacement for higher-order animals in future tests. In addition, using a robot could reduce the amount of live test subjects needed for experiments.

The findings are published in the journal PLOS One.

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