The internal sensory systems enable the brain to receive signals from within the body to generate our internal senses, such as hunger, satiety, thirst, nausea, hypoxia, and visceral pain. How does the brain differentiate hunger pangs from the feeling of fullness? Or the sense of nausea when toxins are ingested? Why does stomach stretch lead to satiety while bladder stretch produces the urge to urinate?

To tackle these questions, we have developed a novel in vivo two-photon mouse brainstem calcium imaging platform. This system allowed us, for the first time, to record the activities of thousands of neurons, with single-cell resolution, in the brain’s gateway to the internal organs. By delivering different types of stimuli to the animal's internal organs, such as stomach stretch, nutrient ingestion, and organ pain, we could observe how different populations of neurons respond to these stimuli. Our previous work using this system (see the example image and video) revealed that internal organs are topographically represented in the brainstem, forming a “visceral homunculus”.

Combining in vivo functional imaging, electrophysiological recordings, mouse genetics, neuronal activity manipulation (optogenetics, chemogenetics), animal behavior, neural circuit tracing, and others, our lab seeks to unravel how the nervous system detects mechanical, chemical, and thermal stimuli from the periphery to synthesize our internal sensations, including satiety, hunger, nausea, hypoxia, and visceral pain. Our research discoveries will uncover fundamental principles of how the brain encodes and processes information, shedding light on the development of novel therapeutics for various conditions, such as hypertension, obesity, diabetes, indigestion, eating disorders, pulmonary diseases, nausea, visceral pain, infection-induced sickness behaviors, and more.