How different afferent inputs control motoneuron discharge and the output of the motoneuron pool

Marc D. Binder*, C. J. Heckman, Randall K. Powers

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

47 Scopus citations

Abstract

In theory, there are at least two distinct mechanisms by which afferent inputs could alter motoneuron discharge and shape the output of a motoneuron pool: either by delivering synaptic current to the motoneurons' somata ('classic' synaptic transduction); or by altering the motoneurons' voltage-sensitive conductances (neuromodulation). Recent work has confirmed the operation of both of these mechanisms. It has been shown that the effect of a 'classic' synaptic input on motoneuron firing rate is predicted by the product of the effective synaptic current and the slope of the motoneuron's frequency-current relation. It has also been shown that neuromodulators can alter both the slope of a motoneuron's frequency-current relation and its threshold for repetitive firing. It is argued here, however, that when two or more sources of synaptic input are activated concurrently, the distinction between these two mechanisms is blurred. Computer simulations of motoneuron and motor pool behavior have proved extremely useful in understanding these processes.

Original languageEnglish (US)
Pages (from-to)1028-1034
Number of pages7
JournalCurrent opinion in neurobiology
Volume3
Issue number6
DOIs
StatePublished - Dec 1993

Funding

The research work carried out in our laboratories is supported by grants from the National Institutes of Health (NS 26840 to MD Binder) and from the Medical Research Service, Department of Veteran Affairs (Merit Review to CJ Heckman).

ASJC Scopus subject areas

  • General Neuroscience

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