eLife Assessment
This is an important study on the sensory roles of Cerebrospinal fluid-contacting neurons (CBF-cn) in mammals. The authors identify PKD2L1 as the predominant pH-sensing channel CBF-cn and show how the apical extension is used as an amplifier of chemical changes in the content of the Cerebrospinal fluid. The evidence is solid in experimental design but limited in mechanistic interpretation, as the electrophysiological analyses require re-evaluation.