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Author Notes:

Correspondence should be addressed to Shawn Hochman, Department of Physiology, 615 Michael Street, Emory University, Atlanta, GA 30322. E-mail: shochma@emory.edu.

We thank Mike Sawchuk and Maggie Hatcher for technical assistance.

We also thank Pete Wenner for discussions while the work was in progress.

Subjects:

Research Funding:

This work was supported by National Institutes of Health Grant NS040893.

Keywords:

  • recurrent
  • excitation
  • motoneuron
  • collateral
  • glutamatergic
  • cholinergic

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

Tools:

Journal Title:

Journal of Neuroscience Nursing

Volume:

Volume 26, Number 22

Publisher:

, Pages 5920-5928

Type of Work:

Article | Post-print: After Peer Review

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.

Copyright information:

© 2006 Society for Neuroscience

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