Aerotaxis Assay in Caenorhabditis elegans to Study Behavioral Plasticity

C. elegans shows robust and reproducible behavioral responses to oxygen. Specifically, worms prefer O ₂ levels of 5-10% and avoid too high or too low O ₂ . Their O ₂ preference is not fixed but shows plasticity depending on experience, context, or genetic background. We recently showed that this experience-dependent plasticity declines with age, providing a useful behavioral readout for studying the mechanisms of age-related decline of neural plasticity. Here, we describe a technique to visualize behavioral O ₂ preference and its plasticity in C. elegans , by creating spatial gradients of [O ₂ ] in a microfluidic polydimethylsiloxane (PDMS) chamber and recording the resulting spatial distribution of the animals.