Research in his laboratory centers on a class of molecules called neuropeptides - short peptides that classically act in the central and peripheral nervous systems to control a wide variety of behaviors and neurological processes. Much of their efforts have focused on two structurally-related peptides that are widely expressed in neurons, vasoactive intestinal peptide (VIP), and pituitary adenylate cyclase activating peptide (PACAP). These neuropeptides are rather unusual because they function not only as neurotransmitters, regulating processes such as circadian rhythms, cognition, and stress responses, but as pleiotropic growth factors and immunomodulators. They employ gene knockout and viral delivery strategies as primary tools to study the biological functions of these peptides. In their early work, they established roles of VIP and PACAP in several aspects of brain development and neural repair, and more recently, they delineated their actions as modulators of inflammation in models of multiple sclerosis ad primary neurodegenerative diseases such as Parkinsons Disease. Finally, based on recent genetic links of mutations in VIP and PACAP signaling genes to schizophrenia and post-traumatic stress disorder (PTSD), they have begun to study the involvement of these peptides in the neurocircuities underlying adaptive responses to fear and stress.