Interactions between focused synaptic inputs and diffuse neuromodulation in the spinal cord

Research output: Chapter in Book/Report/Conference proceedingConference contribution

23 Scopus citations


Spinal motoneurons (MNs) amplify synaptic inputs by producing strong dendritic persistent inward currents (PICs), which allow the MN to generate the firing rates and forces necessary for normal behaviors. However, PICs prolong MN depolarization after the initial excitation is removed, tend to "wind-up" with repeated activation and are regulated by a diffuse neuromodulatory system that affects all motor pools. We have shown that PICs are very sensitive to reciprocal inhibition from Ia afferents of antagonist muscles and as a result PIC amplification is related to limb configuration. Because reciprocal inhibition is tightly focused, shared only between strict anatomical antagonists, this system opposes the diffuse effects of the descending neuromodulation that facilitates PICs. Because inhibition appears necessary for PIC control, we hypothesize that Ia inhibition interacts with Ia excitation in a "push-pull" fashion, in which a baseline of simultaneous excitation and inhibition allows depolarization to occur via both excitation and disinhibition (and vice versa for hyperpolarization). Push-pull control appears to mitigate the undesirable affects associated with the PIC while still taking full advantage of PIC amplification.

Original languageEnglish (US)
Title of host publicationNeurons and Networks in the Spinal Cord
PublisherBlackwell Publishing Inc.
Number of pages7
ISBN (Print)9781573317788
StatePublished - Jun 2010

Publication series

NameAnnals of the New York Academy of Sciences
ISSN (Print)0077-8923
ISSN (Electronic)1749-6632


  • PIC
  • motoneuron
  • neuromodulation
  • push-pull

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)
  • Neuroscience(all)
  • History and Philosophy of Science


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