Development of postural adjustments in sitting position during the first half year of life

Area of Science:

• Developmental motor control
• Infant biomechanics
• Neuroscience

Background:

• Understanding the development of postural control in infants is crucial for assessing motor development.
• Early postural adjustments are foundational for upright stability and complex motor skills.
• Limited research exists on how infants develop postural responses to external disturbances.

Purpose of the Study:

• To investigate the development of postural adjustments in healthy term infants from 1 to 5 months of age.
• To analyze the relationship between postural activity and spontaneous motor behavior during development.
• To identify age-specific changes and patterns in infant postural control.

Main Methods:

• Studied 40 healthy term infants (1-5 months old) and included data from 26 older infants (6-10 months).
• Recorded surface electromyograms (EMG) of neck, trunk, and leg muscles during sudden postural perturbations (forward/backward surface displacements).
• Analyzed video recordings of spontaneous motor behavior alongside EMG data.

Main Results:

• Postural adjustments were direction-specific and highly variable across all ages studied.
• A transient decrease in postural activity was observed around 3 months of age.
• Following this period, direction-specific postural activity, particularly dorsal activity, correlated with spontaneous motor behavior.

Conclusions:

• Infant postural development is characterized by increasing direction-specific adjustments and variability.
• A transient dip in postural activity at 3 months suggests a critical developmental phase.
• The maturation of postural control is linked to the development of spontaneous motor behaviors.