Comprehensive functional screening of taste sensation in vivo

The initial event in taste sensation is mediated by taste cells on the tongue that translate ingested chemicals into cellular signals. Current understanding on this cellular level taste encoding process has relied on ex vivo model systems that cannot fully recapitulate natural cellular microenvironment in vivo. To resolve this methodological limitation, we invented a microfluidics-on-a-tongue imaging chamber that has integrated multichannel microfluidics for auto-controlled tastant delivery. Using this system, we screened over 100 fungiform taste cells to the five basic taste qualities, and obtained comprehensive functional maps. We revealed that taste cells are composed of 70% of single-tuned and 30% of dual-tuned cells, and also discovered a novel population of dual-tuned taste cells encoding a positive valence. We believe that our novel screening platform will pave a way for the deeper understanding of taste coding logic.