Abstract
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.