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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
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Developing electrical properties of postnatal mouse lumbar motoneurons
Jacques Durand1, Anton Filipchuk1, Arnaud Pambo-Pambo1
1Institut de Neurosciences de la Timone, Aix Marseille Université - CNRS, UMR 7289 Marseille, France.
Frontiers in Cellular Neuroscience
|September 22, 2015
Summary
During early mouse development, lumbar motoneuron electrical properties rapidly change, influencing motor control before weight-bearing. These changes correlate with dendritic growth and firing patterns, indicating a critical developmental switch.
Area of Science:
- Neuroscience
- Developmental Biology
- Motor Control
Background:
- Lumbar motoneurons are crucial for locomotion.
- Their electrical properties undergo significant maturation during early postnatal development.
- Understanding these changes is key to deciphering motor control acquisition.
Purpose of the Study:
- To investigate the rapid changes in electrical properties of lumbar motoneurons between postnatal days 3 and 9 in mice.
- To correlate these electrical changes with dendritic morphology and firing patterns.
- To identify distinct motoneuron firing types and their developmental trajectory.
Main Methods:
- Electrophysiological recordings of lumbar motoneurons in mice from postnatal day 3 to 9.
- Analysis of input conductance, rheobase, and input resistance (Rin).
- Classification of motoneurons based on firing patterns during current pulse injection and current ramps.
Main Results:
- Input conductance and rheobase increased significantly up to postnatal day 8.
- Input resistance (Rin) negatively correlated with rheobase and dendritic surface area.
- Distinct firing patterns (transient, delayed onset, sustained) emerged, with transient types decreasing and sustained types increasing with age.
- New firing types, including a 'transient' type during current ramps, were identified and showed age-dependent changes.
Conclusions:
- Lumbar motoneuron electrical properties undergo substantial, rapid changes during the first postnatal week.
- These changes are linked to dendritic maturation and the emergence of specific firing patterns.
- A significant developmental switch in motoneuron electrical properties likely occurs in the second postnatal week, preceding and enabling mature motor function.
