Motoneuron intrinsic properties, but not their receptive fields, recover in chronic spinal injury

Michael D. Johnson, Elma Kajtaz, Charlette M. Cain, C. J. Heckman

Research output: Contribution to journalArticle

14 Scopus citations

Abstract

Proper movement execution relies on precise input processing by spinal motoneurons (MNs). Spinal MNs are activated by limb joint rotations. Typically, their movement-related receptive fields (MRRFs) are sharply focused and joint-specific. After acute spinal transection MRRFs become wide, but their manifestation is not apparent, as intrinsic excitability, primarily resulting from the loss of persistent inward currents (PICs), dramatically decreases. PICs undergo a remarkable recovery with time after injury. Here we investigate whether MRRFsundergo a recovery that parallels that of the PIC. Using the chronic spinal cat in acute terminal decerebrate preparations,wefound that MRRFs remain expanded 1 month after spinal transaction, whereas PICs recovered to > 80% of their preinjury amplitudes. These recovered PICs substantially amplified the expanded inputs underlying the MRRFs. As a result, we show that single joint rotations lead to the activation of muscles across the entire limb. These results provide a potential mechanism for the propagation of spasms throughout the limb.

Original languageEnglish (US)
Pages (from-to)18806-18813
Number of pages8
JournalJournal of Neuroscience
Volume33
Issue number48
DOIs
StatePublished - Jan 1 2013

ASJC Scopus subject areas

  • Neuroscience(all)

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