RT Journal Article
SR Electronic
T1 Functional and ultrastructural analysis of reafferent mechanosensation in larval zebrafish
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2021.05.04.442674
DO 10.1101/2021.05.04.442674
A1 Iris Odstrcil
A1 Mariela D. Petkova
A1 Martin Haesemeyer
A1 Jonathan Boulanger-Weill
A1 Maxim Nikitchenko
A1 James A. Gagnon
A1 Pablo Oteiza
A1 Richard Schalek
A1 Adi Peleg
A1 Ruben Portugues
A1 Jeff Lichtman
A1 Florian Engert
YR 2021
UL http://biorxiv.org/content/early/2021/05/06/2021.05.04.442674.abstract
AB All animals need to differentiate between exafferent stimuli, which are caused by the environment, and reafferent stimuli, which are caused by their own movement. In the case of mechanosensation in aquatic animals, the exafferent inputs are water vibrations in the animal’s proximity, which need to be distinguished from the reafferent inputs arising from fluid drag due to locomotion. Both of these inputs are detected by the lateral line, a collection of mechanosensory organs distributed along the surface of the body.In this study, we characterize in detail how the hair cells, which are the receptor cells of the lateral line, discriminate between such reafferent and exafferent signals in zebrafish larvae. Using dye labeling of the lateral line nerve, we visualize two parallel descending inputs that can influence lateral line sensitivity. We combine functional imaging with ultra-structural EM circuit reconstruction to show that cholinergic signals originating from the hindbrain transmit efference copies that cancel out self-generated reafferent stimulation during locomotion, and that dopaminergic signals from the hypothalamus may have a role in threshold modulation both in response to locomotion and salient stimuli. We further gain direct mechanistic insight into the core components of this circuit by loss-of-function perturbations using targeted ablations and gene knockouts.We propose that this simple circuit is the core implementation of mechanosensory reafferent suppression in these young animals and that it might form the first instantiation of state-dependent modulation found at later stages in development.Competing Interest StatementThe authors have declared no competing interest.