Time: 14:00-15:30 on Tue.,Sep.26, 2023

Venue：E109, Biomedicine Hall

Speaker: Dr.Chen Ran

Host: Dr.Mu Zhou

Title: The coding of visceral organ sensations in the brain

Abstract：

The discoveries of the coding principles of vision, somatosensation, olfaction, gustation, and audition are all landmark achievements. By contrast, little is known about how the brain encodes information from the internal organs to generate our visceral senses, including satiety, hunger, thirst, hypoxia, palpitation, nausea, and visceral pain. This missing piece of the puzzle prevents a complete understanding of how the brain combines sensory information and internal states to guide behavior. 

My work developed an in vivo two-photon mouse brainstem calcium imaging preparation to study the representations of internal organs in the nucleus of the solitary tract (NTS), a viscerosensory gateway in the brainstem that receives bodily cues through the vagus nerve. I discovered that the NTS uses a combinatorial code to represent diverse mechanical and chemical stimuli within the same organ. By contrast, different organs are represented by discrete and selectively tuned neuronal ensembles, each comprised of heterogeneous cell types. Organ representations are topographically organized, forming a “visceral homunculus” in the brainstem. Spatial organization of different organs is further sharpened by inhibition, as blockade of NTS inhibition broadens neural tuning and blurs visceral representations. These studies reveal basic coding principles used by the brain to process visceral inputs. 

This project allows me to build a research platform in the future to systematically investigate the representations of internal senses throughout the brain. As information ascends in the brain, the coding of basic physical variables of force, chemicals, temperature, and osmolarity are transformed into the coding of cognitive features of satiety, thirst, nausea, hypoxia, and visceral pain in higher-order sensory regions. Understanding how key coding features arise or dissipate in each brain region will elucidate the role of that brain region in circuit computations, and more generally, how the brain encodes information.