Decoupling kinematics and mechanics reveals coding properties of trigeminal ganglion neurons in the rat vibrissal system

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Abstract

Tactile information available to the rat vibrissal system begins as external forces that cause whisker deformations, which in turn excite mechanoreceptors in the follicle. Despite the fundamental mechanical origin of tactile information, primary sensory neurons in the trigeminal ganglion (Vg) have often been described as encoding the kinematics (geometry) of object contact. Here we aimed to determine the extent to which Vg neurons encode the kinematics vs. mechanics of contact. We used models of whisker bending to quantify mechanical signals (forces and moments) at the whisker base while simultaneously monitoring whisker kinematics and recording single Vg units in both anesthetized rats and awake, body restrained rats. We employed a novel manual stimulation technique to deflect whiskers in a way that decouples kinematics from mechanics, and used Generalized Linear Models (GLMs) to show that Vg neurons more directly encode mechanical signals when the whisker is deflected in this decoupled stimulus space.

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Nicholas E Bush

Interdepartmental Neuroscience Program, Northwestern University, Evanston, United States

Competing interests
The authors declare that no competing interests exist.
Christopher L Schroeder

Department of Biomedical Engineering, Northwestern University, Evanston, United States

Competing interests
The authors declare that no competing interests exist.
Jennifer A Hobbs

Department of Physics and Astronomy, Northwestern University, Evanston, United States

Competing interests
The authors declare that no competing interests exist.
Anne ET Yang

Department of Mechanical Engineering, Northwestern University, Evanston, United States

Competing interests
The authors declare that no competing interests exist.
Lucie A Huet

Department of Mechanical Engineering, Northwestern University, Evanston, United States

Competing interests
The authors declare that no competing interests exist.
Sara A Solla

Department of Physics and Astronomy, Northwestern University, Evanston, United States

Competing interests
The authors declare that no competing interests exist.
Mitra JZ Hartmann

Department of Biomedical Engineering, Northwestern University, Evanston, United States

For correspondence
hartmann@northwestern.edu

Competing interests
The authors declare that no competing interests exist.

Ethics

Animal experimentation: All procedures involving animals were approved in advance by the Northwestern University Animal Care and Use Committee protocols #2012-1776 and #2015-1575.

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This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.