Our laboratory uses mouse genetic models and viral gene transfer to dissect neural circuits involved in innate behaviors. We start by making genetically engineered mice that target expression of Cre recombinase to genes that are expressed in specific subsets of neurons, typically genes encoding neuropeptides or their receptors. We then stereotaxically inject viruses expressing Cre-dependent genes (e.g., genes encoding fluorescent proteins, genes that allow activation or inhibition of neuron activity by light or chemicals, or genes that prevent all neurotransmission or kill neurons) into brain regions of interest. The aims of these studies are to (a) visualize where the neurons are located and where they project their axons, (b) record the activity of neurons in real time based on calcium-induced fluorescence, (c) evaluate the behavioral/physiological consequences of activating or inhibiting those neurons either transiently or permanently.