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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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A size principle for bistability in mouse spinal motoneurons
Biorxiv : the Preprint Server for Biology
|October 9, 2023
Summary
Bistability, crucial for tonic activity, is more prevalent in larger spinal motoneurons. This size-dependent difference in bistability and ionic currents suggests a role for fast motoneurons in maintaining posture.
Area of Science:
- Neuroscience
- Motor Control
- Cellular Electrophysiology
Background:
- Spinal motoneuron bistability supports tonic activity without excitatory drive.
- Previous studies suggested smaller motoneurons are key for postural maintenance.
- The role of large motoneurons in postural tone via bistability remains debated.
Approach:
- Investigated soma size and bistability in mouse lumbar ventrolateral α-motoneurons across developmental stages (neonatal, young, mature).
- Utilized ChAT-GFP and Hb9-GFP mouse lines for motoneuron identification.
- Examined ionic currents (Nav1.6, Trpm5, Kv1.2) and serotonin's effect on bistability.
Key Points:
- Bistability prevalence increases with motoneuron size.
- Smaller α-motoneurons lack bistability; larger fast α-motoneurons (soma area ≥ 400µm²) show significantly higher bistability.
- Ionic currents underlying bistability scale with cell size; serotonin enhances bistability in large motoneurons.
Conclusions:
- Motoneuron size is a critical determinant of bistability.
- Differential expression of ionic currents contributes to size-dependent bistability.
- Findings suggest fast motoneurons may contribute to tonic posture maintenance.
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