To determine whether alcohol would affect fear responses, the researchers exposed separate groups of fish to different doses of ethanol in water. Ethanol has been shown to influence anxiety-related responses in humans, rodents and some species of fish. The zebrafish exposed to the highest concentrations of ethanol showed remarkable changes in behavior, failing to avoid the predatory robot. Acute administration of ethanol causes no harm and has no lasting effect on zebrafish.
"These results are further evidence that robots may represent an exciting new approach in evaluating and understanding emotional responses and behavior," said Porfiri. "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."
To validate their findings and ensure that the zebrafish behavior being modulated was, in fact, a fear-based response, Porfiri and his collaborators conducted two traditional anxiety tests and evaluated whether the results obtained therein were sensitive to ethanol administration.
They placed test subjects in a two-chamber tank with one well-lit side and one darkened side, to establish which conditions were preferable. In a separate tank, they simulated a heron attack from the water's surface — herons also prey on zebrafish — and measured how quickly and how many fish took shelter from the attack. As expected, the fish strongly avoided the dark compartment, and most sought shelter very quickly from the heron attack. Ethanol exposure significantly modulated these fear responses as well, abolishing the preference for the light compartment and significantly slowing the fishes' retreat to shelter during the
|SOURCE Polytechnic Institute of New York University|
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