The common theme of research projects in the Sisk Lab is the influence of steroid hormones on nervous system structure and function. Gonadal steroids, such as testosterone, estrogen, and progesterone, profoundly affect neuronal activity, connectivity within neural circuits, and behavior at different stages of life, including early neural development, puberty, and in adulthood. Neural and behavioral responses to steroid hormones vary with developmental stage. Our work focuses on the role of pubertal hormones in shaping development of the adolescent brain and maturation of adult behaviors, and it contributes to an understanding of the ways and extent to which the capacity for functional plasticity within the nervous system changes across the lifespan. Research in the Sisk Lab is a combination of neuroendocrinology, developmental neurobiology, and behavioral neuroscience. We employ a variety of experimental techniques, ranging from analysis of gene expression to analysis of behavior.