We use a combination of molecular, cellular, immunohistochemical, electrophysiological, genetic and behavioral approaches to understand how the nervous system receives, transmits and interprets various stimuli to induce physiological and behavioral responses. We are particularly interested in the basic mechanisms underlying somatosensation, including pain, itch and mechanical sensations. Somatosensation is initiated by the activation of the primary sensory neurons in dorsal root ganglia and trigeminal ganglia. We have discovered the molecular identity of itch-sensing neurons in the peripheral and provided novel insights into the mechanisms of itch sensation (Han et.al. 2013 Nature Neuroscience). We are currently investigating how chronic itch associated with cutaneous or systemic disorders is initiated and transmitted. We are also interested in the sensory innervation in the respiratory system. Chronic respiratory diseases such as asthma and chronic obstructive pulmonary disease (COPD) are leading causes of illness and significant public health burdens. We recently identified a subset of vagal sensory neurons mediating bronchoconstriction and airway hyperresponsiveness (Han et. al. 2017 Nature Neuroscience). We are investigating how the sensory innervations in the airway contribute to the pathogenesis of respiratory diseases.