Complexin-1 enhances ultrasound neurotransmission in the mammalian auditory pathway.

Unlike megabats, which rely on well-developed vision, microbats use ultrasonic echolocation to navigate and locate prey. To study ultrasound perception, here we compared the auditory cortices of microbats and megabats by constructing reference genomes and single-nucleus atlases for four species. We found that parvalbumin (PV) + neurons exhibited evident cross-species differences and could respond to ultrasound signals, whereas their silencing severely affected ultrasound perception in the mouse auditory cortex. Moreover, megabat PV + neurons expressed low levels of complexins (CPLX1-CPLX4), which can facilitate neurotransmitter release, while microbat PV + neurons highly expressed CPLX1, which improves neurotransmission efficiency. Further perturbation of Cplx1 in PV + neurons impaired ultrasound perception in the mouse auditory cortex. In addition, CPLX1 functioned in other parts of the auditory pathway in microbats but not megabats and exhibited convergent evolution between echolocating microbats and whales. Altogether, we conclude that CPLX1 expression throughout the entire auditory pathway can enhance mammalian ultrasound neurotransmission.