Repeated amphetamine exposure increased maze alternation in zebrafish, a pattern interpreted as improved working memory, while reducing other exploratory strategies and flexibility. The findings do not support an unqualified cognitive-enhancement claim.
The study exposed adult zebrafish repeatedly and intermittently to d-amphetamine or nicotine over 14 days, then examined a challenge after a short withdrawal period. The FMP Y-maze recorded repeated left–right choices, allowing analysis of alternation patterns, exploration and movement. Drug solutions were administered in aquarium water, a route unlike oral or injected human exposure.
Amphetamine increased alternation, with a further increase after challenge, consistent with sensitization of that behavioral measure. However, the pattern coincided with hypolocomotion, reduced use of other search strategies and inhibited flexibility. Nicotine produced a partly different profile. Alternation frequency is a task-derived indicator: a more repetitive choice sequence must be interpreted alongside the wider behavioral pattern.
The experiment did not measure human memory or show that the fish developed the clinical syndrome of addiction. Sensitization is an operational response to repeated exposure, not by itself proof of dependence or future relapse. Water concentration, uptake and species physiology also prevent direct human dose translation. The useful conclusion is that a favorable result on one candidate cognitive measure can coexist with less flexible behavior. Keeping those outcomes together prevents the headline of improved memory from erasing the limitations supplied by the same experiment.
See a human sensitization experiment separating subjective and reward-related responses.