Accessing Olfactory Habituation in Drosophila melanogaster with a T-maze Paradigm.

Habituation is the process whereby perceptual changes alter the value of environmental stimuli, enabling salience filtering. This behavioral response decrement is a form of non-associative learning, where the subject learns about the stimulus and does not involve sensory adaptation, sensory or motor fatigue. The range of behavioral responses in D. melanogaster led to the development of a number of habituation paradigms addressing various sensory modalities. Habituation of osmotactic responses has previously been measured with the Y-maze test and required 30 min of odor exposure. Here, we describe an olfactory habituation assay utilizing the widely used in associative learning paradigms T-maze. Continuous or repetitive odor exposure for 4 min is adequate to attenuate osmotactic responses both to attractive and aversive odors. Importantly, the decreased response conforms to habitation parameters, presenting dishabituation and spontaneous recovery. This assay allows the study of habituation after brief odor exposure, but also discriminates between the two distinct phases of the response, an initial habituation latency period followed by habituation. In addition, the characterization of the neuronal circuits implicated in each phase facilitates further study of the molecular components underlying this process.