A rapid and bidirectional reporter of neural activity reveals neural correlates of social behaviors inDrosophila

ABSTRACT Neural activity is modulated over different timescales encompassing sub-seconds to days reflecting changes in external environment, internal state, and behavior. Using Drosophila as a model, we have developed a rapid and bidirectional reporter that provides a robust cellular readout of recent neural activity. This reporter utilizes nuclear vs cytoplasmic distribution of CREB-regulated transcriptional coactivator, CRTC. Subcellular distribution of GFP-tagged CRTC (CRTC::GFP) bidirectionally changes on the order of minutes and reflects both increases and decreases in neural activity. We establish an automated machine-learning-based routine for efficient quantification of reporter signal. Using this reporter, we demonstrate acute mating- evoked activation of peptidergic neurons. We further investigate the functional role of the master courtship regulator gene, fruitless , and show that fruitless is necessary to ensure activation of male arousal neurons by female cues. Together, our results establish CRTC::GFP as a bidirectional reporter of recent neural activity suitable for examining neural correlates in behavioral contexts.