Homeostasis is a hallmark of biological systems. To survive, an organism needs to adapt to the demands of the external environment and change its behavioral and physiological responses appropriately. The stress response refers to complex adaptive responses of an animal to environmental stimuli that threaten homeostasis. While crucial for the survival of an animal in a short term, a prolonged stress response is implicated in a number of disorders in humans including depression. In establishing this important response, the early life environment plays a major role. It is known that exposure to stress during early development can permanently alter brain function. Furthermore, through interactions with the environment, brain stress circuits are built and optimized to respond to future stressors appropriately. The research group ‘Developmental Genetics of the Nervous System’ was established in July 2008 with the long-term goal of understanding the mechanisms that underlie the development and function of the stress circuit both at a physiological and behavioral level and how it becomes malfunctional in certain individuals. We use zebrafish as a model system, because it is a simpler vertebrate where powerful genetic, optogenetic and imaging approaches can be combined to dissect complex stress behavior and neuronal developmental processes. Our basic approach is to combine tools available in developmental biology with those available in circuit function and behavioral analysis.