TY  - JOUR
A1  - Butler, Victoria J.
A1  - Branicky, Robyn
A1  - Yemini, Eviatar
A1  - Liewald, Jana F.
A1  - Gottschalk, Alexander
A1  - Kerr, Rex A.
A1  - Chklovskii, Dmitri B.
A1  - Schafer, William R.
T1  - A consistent muscle activation strategy underlies crawling and swimming in Caenorhabditis elegans
T2  - Interface
N2  - Although undulatory swimming is observed in many organisms, the neuromuscular basis for undulatory movement patterns is not well understood. To better understand the basis for the generation of these movement patterns, we studied muscle activity in the nematode Caenorhabditis elegans. Caenorhabditis elegans exhibits a range of locomotion patterns: in low viscosity fluids the undulation has a wavelength longer than the body and propagates rapidly, while in high viscosity fluids or on agar media the undulatory waves are shorter and slower. Theoretical treatment of observed behaviour has suggested a large change in force–posture relationships at different viscosities, but analysis of bend propagation suggests that short-range proprioceptive feedback is used to control and generate body bends. How muscles could be activated in a way consistent with both these results is unclear. We therefore combined automated worm tracking with calcium imaging to determine muscle activation strategy in a variety of external substrates. Remarkably, we observed that across locomotion patterns spanning a threefold change in wavelength, peak muscle activation occurs approximately 45° (1/8th of a cycle) ahead of peak midline curvature. Although the location of peak force is predicted to vary widely, the activation pattern is consistent with required force in a model incorporating putative length- and velocity-dependence of muscle strength. Furthermore, a linear combination of local curvature and velocity can match the pattern of activation. This suggests that proprioception can enable the worm to swim effectively while working within the limitations of muscle biomechanics and neural control.
KW  - Caenorhabditis elegans
KW  - locomotion
KW  - gait adaptation
KW  - phase-shift
KW  - biophysics
KW  - muscle activity
Y1  - 2017
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/43908
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-439089
SN  - 1742-5689
SN  - 1742-5662
N1  - © The Authors. Published by the Royal Society under the terms of the Creative Commons AttributionLicense http://creativecommons.org/licenses/by/4.0/, which permits unrestricted use, provided the originalauthor and source are credited.
VL  - 12
IS  - 102, Art. 20140963
SP  - 1
EP  - 12
PB  - The Royal Society
CY  - London
ER  -