Project Summary Sensory adaptation is an important feature of all sensory systems, as it allows them to maintain sensitivity over a wide range in backgrounds of varying stimulation. Here, we introduce Na+-activated K+ (KNa/Slo2) channels a new player to the mechanisms that underlie sensory adaptation. Studies over the years have suggested that KNa/Slo2 channels might function to dampen activity in states of excessive excitation. KNa/Slo2 channels are unique in that the major depolarizing ion, Na+, activates a repolarizing K+-selective pore; thus by nature, these channels seem designed to be a built-in hyperpolarizing mechanism against episodes of excessive excitation. In the proposed studies, we use Drosophila as a model system in which to genetically manipulate dSlo2 expression, test for olfactory adaptation in vivo, identify the cells and subcellular domains in which dSlo2 channels affect adaptation, and electrophysiologically examine the role of dSlo2 channels in the excitability of these cells.