Please use this identifier to cite or link to this item:
Title: Motor inhibition affects the speed but not accuracy of aimed limb movements in an insect.
Authors: Calas-List, Delphine
Clare, Anthony J.
Komissarova, Alexandra
Nielsen, Thomas A.
Matheson, Thomas
First Published: 28-May-2014
Publisher: Society for Neuroscience
Citation: J Neurosci, 2014, 34 (22), pp. 7509-7521
Abstract: When reaching toward a target, human subjects use slower movements to achieve higher accuracy, and this can be accompanied by increased limb impedance (stiffness, viscosity) that stabilizes movements against motor noise and external perturbation. In arthropods, the activity of common inhibitory motor neurons influences limb impedance, so we hypothesized that this might provide a mechanism for speed and accuracy control of aimed movements in insects. We recorded simultaneously from excitatory leg motor neurons and from an identified common inhibitory motor neuron (CI1) in locusts that performed natural aimed scratching movements. We related limb movement kinematics to recorded motor activity and demonstrate that imposed alterations in the activity of CI1 influenced these kinematics. We manipulated the activity of CI1 by injecting depolarizing or hyperpolarizing current or killing the cell using laser photoablation. Naturally higher levels of inhibitory activity accompanied faster movements. Experimentally biasing the firing rate downward, or stopping firing completely, led to slower movements mediated by changes at several joints of the limb. Despite this, we found no effect on overall movement accuracy. We conclude that inhibitory modulation of joint stiffness has effects across most of the working range of the insect limb, with a pronounced effect on the overall velocity of natural movements independent of their accuracy. Passive joint forces that are greatest at extreme joint angles may enhance accuracy and are not affected by motor inhibition.
DOI Link: 10.1523/JNEUROSCI.2200-13.2014
ISSN: 0270-6474
eISSN: 1529-2401
Version: Publisher Version
Status: Peer-reviewed
Type: Journal Article
Rights: Copyright © 2014 Calas-List et al. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (, which permits unrestricted use, distribution and reproduction in any medium provided that the original work is properly attributed.
Description: PMCID: PMC4035516
Appears in Collections:Published Articles, Dept. of Biology

Files in This Item:
File Description SizeFormat 
Calas-List_et_al_JNeurosci_2014.pdfPublished (publisher PDF)3.96 MBAdobe PDFView/Open

Items in LRA are protected by copyright, with all rights reserved, unless otherwise indicated.