Differential impact of artificial light at night on cognitive flexibility in visual and spatial reversal learning tasks

Artificial light at night (ALAN) is a pervasive environmental pollutant with multiple adverse effects on animal biology. As the vertebrate nervous system is particularly sensitive to light effects, this study explores the potential negative impact of ALAN on cognition in adult zebrafish, Danio rerio. Fish from mesocosm populations exposed to either ALAN or control conditions underwent visual and spatial learning tasks, along with an evaluation of cognitive flexibility with visual and spatial reversal learning tasks. Contrary to our initial prediction of a general negative impact, learning performance was not affected by the ALAN treatment. The analysis of reversal learning revealed task-dependent effects on cognitive flexibility: fish exposed to ALAN performed worse than control fish in the visual reversal learning task, but displayed better performance in the spatial reversal learning task. We propose that the influence of ALAN on cognition might differ between different cognitive functions or involve noncognitive factors that play different roles in the testing paradigms. The study underscores the importance of task specificity in nonadaptive cognitive plasticity and calls for ecological assessments to quantify fitness consequences of ALAN in natural settings.