Previous studies show alcohol exposure affects zebrafish locomotionat low concentrations, fish tend to swim faster, and as the dose increases, swimming typically slows. Alcohol can also negatively impact the school's cohesion.
In Porfiri's trials, the single exposed zebrafish showed changes in locomotion when observed alone consistent to those predicted by independent studies in the past. In a group setting, however, the zebrafish behavior was remarkably different: Fish exposed to intermediate or high alcohol concentrations nearly doubled their swimming speeds, suggesting that the presence of peers had a substantial impact on social behavior under the influence of alcohol.
Most remarkably, the unexposed fish also modulated their behavior and swimming speeds differentially in the presence of a shoalmate exposed to different levels of alcohol.
"These results were very surprising," explained Porfiri. "It is clear that the untreated fish were matching the swimming speed of the alcohol-exposed fish, and this correlation was especially strong at an intermediate level of alcohol exposure. At very high or low levels, the influence decreases."
Porfiri believes that one explanation for the high-speed swimming of the exposed individual may be hyper-reactivity to an enriched environmentthe tank containing shoalmates. Alcohol has also been shown to decrease inhibitory behavior in zebrafish. The increased speed may therefore also reflect a heightened interest in interacting with shoalmates. Regardless, this deviation from expected behavior is highly significant, as it points to the ability of social stimuli (the untreated shoalmates) to change an individual's response to alcohol.
The ability of alcohol-exposed zebrafish to influence untreated shoalmates may constitute a form of leadership, but researchers caution that aggressive,
|Contact: Kathleen Hamilton|
New York University Polytechnic School of Engineering