Related Experiment Videos
The effect of activity during early postnatal development on motor unit size
1Department of Anatomy and Developmental Biology, University College London, Gower Street, London WC1E 6BT, UK. g.vrbova@ucl.ac.uk
Canadian Journal of Physiology and Pharmacology
|November 4, 2004
Summary
Nerve activity during development speeds up motor unit maturation but does not alter the final distribution of motor unit sizes in rat muscles. This finding clarifies the role of activity in neuromuscular development.
Area of Science:
- Neuroscience
- Developmental Biology
- Muscle Physiology
Background:
- During neuromuscular development, motor unit territory initially expands, with synapses and motor unit size decreasing postnatally.
- This developmental process is activity-dependent, accelerating with nerve activation and slowing with reduced activity.
Purpose of the Study:
- To investigate if neural activity during a critical developmental period influences the final distribution of motor unit sizes.
- To determine if activity affects the ultimate outcome of motor unit size, beyond just the rate of development.
Main Methods:
- Daily sciatic nerve stimulation was applied to 8- to 12-day-old rats.
- Muscle tension and individual motor unit sizes were recorded one week after stimulation.
- Motor unit size distributions from stimulated and control groups were compared.
Main Results:
- No significant difference was observed in the distribution of motor unit sizes between stimulated and control muscles.
- Activity influenced the rate of motor unit size attainment but not the final distribution.
Conclusions:
- Nerve activity accelerates the rate at which motor units reach their adult size during development.
- Activity does not alter the final distribution of motor unit sizes, suggesting other factors determine the adult outcome.