Force-sensitive afferents recruited during stance encode sensory depression in the contralateral swinging limb during locomotion

• Type of Material: Article
• Authors: Shawn Hochman, Emory University; Heather Brant Hayes, Emory University; Iris Speigel, Emory University; Young-Hui Chang, Georgia Institute of Technology
• Language: English
• Date: 2013-04
• Publisher: Wiley: 12 months
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 New York Academy of Sciences.
• Final Published Version (URL): http://onlinelibrary.wiley.com/doi/10.1111/nyas.12055/abstract
• Title of Journal or Parent Work: Annals of the New York Academy of Sciences
• ISSN: 0077-8923
• Volume: 1279
• Issue: 1
• Start Page: 103
• End Page: 113
• Grant/Funding Information: This work was funded by NIH NS45248, NIH NS65949, and NSF 0745164 to S.H., NIH AR054760 to Y.H.C., and NSF GRFP fellowship to H.B.H.
• Keywords: primary afferent; Golgi tendon organ; presynaptic inhibition; primary afferent depolarization; dorsal root potential
• Research Categories: Biology, Physiology

Abstract

Afferent feedback alters muscle activity during locomotion and must be tightly controlled. As primary afferent depolarization-induced presynaptic inhibition (PAD-PSI) regulates afferent signaling, we investigated hind limb PAD-PSI during locomotion in an in vitro rat spinal cord-hind limb preparation. We compared the relation of PAD-PSI, measured as dorsal root potentials (DRPs), to observed ipsilateral and contralateral limb endpoint forces. Afferents activated during stance-phase force strongly and proportionately influenced DRP magnitude in the swinging limb. Responses increased with locomotor frequency. Electrical stimulation of contralateral afferents also preferentially evoked DRPs in the opposite limb during swing (flexion). Nerve lesioning in conjunction with kinematic results support a prominent contribution from toe Golgi tendon organ afferents. Thus, force-dependent afferent feedback during stance binds interlimb sensorimotor state to a proportional PAD-PSI in the swinging limb, presumably to optimize interlimb coordination. These results complement known actions of ipsilateral afferents on PAD-PSI during locomotion.