Issue 6, 2013

MEMS-based force-clamp analysis of the role of body stiffness in C. elegans touch sensation

Abstract

Touch is enabled by mechanoreceptor neurons in the skin and plays an essential role in our everyday lives, but is among the least understood of our five basic senses. Force applied to the skin deforms these neurons and activates ion channels within them. Despite the importance of the mechanics of the skin in determining mechanoreceptor neuron deformation and ultimately touch sensation, the role of mechanics in touch sensitivity is poorly understood. Here, we use the model organism Caenorhabditis elegans to directly test the hypothesis that body mechanics modulate touch sensitivity. We demonstrate a microelectromechanical system (MEMS)-based force clamp that can apply calibrated forces to freely crawling C. elegans worms and measure touch-evoked avoidance responses. This approach reveals that wild-type animals sense forces <1 μN and indentation depths <1 μm. We use both genetic manipulation of the skin and optogenetic modulation of body wall muscles to alter body mechanics. We find that small changes in body stiffness dramatically affect force sensitivity, while having only modest effects on indentation sensitivity. We investigate the theoretical body deformation predicted under applied force and conclude that local mechanical loads induce inward bending deformation of the skin to drive touch sensation in C. elegans.

Graphical abstract: MEMS-based force-clamp analysis of the role of body stiffness in C. elegans touch sensation

Supplementary files

Article information

Article type
Paper
Submitted
19 Dec 2012
Accepted
09 Apr 2013
First published
19 Apr 2013

Integr. Biol., 2013,5, 853-864

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