Development of postural control--differences between ventral and dorsal muscles?

Area of Science:

• Developmental motor control
• Neuroscience
• Human movement science

Background:

• Postural control relies on direction-specific muscle synergies.
• Early postural development in infants involves adaptable muscle activation patterns.
• Understanding developmental changes in postural control is crucial for assessing motor milestones.

Purpose of the Study:

• To investigate the developmental trajectory of postural control synergies in infants.
• To identify age-related changes in muscle activation patterns during postural adjustments.
• To compare the development of extensor and flexor muscle synergies.

Main Methods:

• Observational study of muscle activation patterns in sitting infants.
• Analysis of direction-specific muscle synergies during postural sway.
• Longitudinal assessment of postural control development from 5-6 months to 3 years.

Main Results:

• Direction-specific muscle activation patterns are present in infants as young as 5-6 months.
• Muscle activation variability decreases with age, with refined synergies emerging around 9-10 months.
• Dorsal extensor synergies develop earlier than ventral flexor synergies, supporting standing and walking.
• A 'fixed' extensor synergy is prominent from 9 months to 3 years, later dissolving.
• Flexor synergies demonstrate greater flexibility than extensor synergies.

Conclusions:

• Infant postural control develops through progressive refinement of direction-specific muscle synergies.
• The maturation sequence of extensor and flexor synergies influences the development of upright locomotion.
• Differences in stability limits and supraspinal modulation may explain varying flexibility between extensor and flexor synergies.