Noradrenaline Unmasks Novel Self-Reinforcing Motor Circuits within the Mammalian Spinal Cord

• Type of Material: Article
• Authors: David W. Machacek, Emory University; Shawn Hochman, Emory University
• Language: English
• Date: 2006-05-31
• Publisher: Society for Neuroscience
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2006 Society for Neuroscience
• Final Published Version (URL): http://www.jneurosci.org/content/26/22/5920.long
• Title of Journal or Parent Work: Journal of Neuroscience Nursing
• ISSN: 0270-6474
• Volume: 26
• Issue: 22
• Start Page: 5920
• End Page: 5928
• Grant/Funding Information: This work was supported by National Institutes of Health Grant NS040893.
• Keywords: cholinergic; excitation; glutamatergic; motoneuron; recurrent; collateral
• Research Categories: Biology, Physiology; Biology, Neuroscience

Abstract

Spiking activity in motor axons represents the final central coding for muscle contraction. Recurrent collaterals in spinal cord from these same axons are known to offer a negative feedback control of motor output via a class of interposed inhibitory interneurons. Here we demonstrate that, during noradrenergic drive, a previously unknown recurrent excitatory pathway is unmasked and expressed. These excitatory projections are shown to have broad bilateral actions within and between hindlimb spinal segments and can alter ongoing pattern-generating motor behaviors. Thus, motor output strength is controlled via central positive and negative feedback loops, undoubtedly to provide a greater flexibility and dynamic range of control. That this novel function is regulated by a descending neuromodulatory transmitter indicates a conditional recruitment during certain behavioral states as part of the central noradrenergic arousal apparatus.