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Updated: May 28, 2026
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Simultaneous Intracellular Recording of a Lumbar Motoneuron and the Force Produced by its Motor Unit in the Adult Mouse In vivo
Published on: December 5, 2012
Contribution of intrinsic properties and synaptic inputs to motoneuron discharge patterns: a simulation study
Randall K Powers1, Sherif M Elbasiouny, W Zev Rymer
1Dept. of Physiology and Biophysics, Univ. of Washington, Seattle, WA 98195, USA. rkpowers@u.washington.edu
Journal of Neurophysiology
|October 28, 2011
Summary
Persistent inward currents (PICs) influence motoneuron firing, but their activation by synaptic inputs is complex. Inhibitory input patterns significantly alter motor unit discharge, creating diverse firing patterns even with PICs.
Area of Science:
- Neuroscience
- Computational Biology
- Motor Control
Background:
- Motoneuron discharge patterns result from synaptic inputs and intrinsic conductances.
- Persistent inward currents (PICs) amplify and prolong synaptic input effects on motoneurons.
- Human motor unit discharge features suggest stereotyped PIC activation, but inhibitory inputs also play a role.
Purpose of the Study:
- To investigate how PIC activation and synaptic input patterns influence motoneuron discharge.
- To model the interplay between excitatory and inhibitory synaptic inputs on motoneuron firing.
Main Methods:
- Utilized cable motoneuron models tuned to cat spinal motoneuron data.
- Simulated responses to various patterns of excitatory and inhibitory synaptic inputs.
Main Results:
- Model responses to excitatory inputs replicated some human motor unit discharge features.
- The temporal and spatial patterns of concurrent inhibitory inputs significantly modulated firing rate.
- Diverse motor unit discharge patterns emerged from combined PIC activation and varied synaptic input patterns.
Conclusions:
- While PICs are crucial for firing rate modulation, their interaction with complex synaptic input patterns generates a wide spectrum of motor unit discharge behaviors.
- Understanding the interplay of excitation and inhibition is key to deciphering motoneuron firing variability.
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