Recent discoveries show that each type of neuron has its own chemical markers that determine its functional role in the brain. Sung Han examines specific markers, called neuropeptides, that influence the brain’s alarm system. The dysfunction of neuropeptide signaling has been directly linked to a variety of human disorders, ranging from neuropsychiatric disorders to metabolic syndromes. Although hundreds of neuropeptides are identified, their functional roles in the brain are not fully understood. To better understand how neuropeptide signaling encodes and processes sensory threats, Han is unraveling individual neural circuits using the latest techniques in the field of neuroscience, including optogenetics, chemogenetics, electrophysiology and in vivo and in vitro functional imaging techniques, among others. Understanding neural circuitry of the brain’s alarm system will provide insight for developing therapeutic interventions for a host of neuropsychiatric disorders with sensory abnormalities.