Citation

Wei K, Glaser JI, Deng L, Thompson CK, Stevenson IH, Wang Q, Hornby TG, Heckman CJ, Körding KP. J. Neurosci. 2014; 34(38): 12690-12700.

Affiliation

Departments of Physical Medicine and Rehabilitation, Physiology, and Applied Mathematics, Northwestern University, Chicago, Illinois 60611, Rehabilitation Institute of Chicago, Chicago, Illinois 60611, and.

Copyright

(Copyright © 2014, Society for Neuroscience)

DOI

10.1523/JNEUROSCI.1855-14.2014

PMID

25232107

Abstract

A fundamental challenge for the nervous system is to encode signals spanning many orders of magnitude with neurons of limited bandwidth. To meet this challenge, perceptual systems use gain control. However, whether the motor system uses an analogous mechanism is essentially unknown. Neuromodulators, such as serotonin, are prime candidates for gain control signals during force production. Serotonergic neurons project diffusely to motor pools, and, therefore, force production by one muscle should change the gain of others. Here we present behavioral and pharmaceutical evidence that serotonin modulates the input-output gain of motoneurons in humans. By selectively changing the efficacy of serotonin with drugs, we systematically modulated the amplitude of spinal reflexes. More importantly, force production in different limbs interacts systematically, as predicted by a spinal gain control mechanism. Psychophysics and pharmacology suggest that the motor system adopts gain control mechanisms, and serotonin is a primary driver for their implementation in force production.

Language: en