Epigenetic development of postural responses for sitting during infancy

Area of Science:

• Developmental neuroscience
• Motor control
• Biophysics

Background:

• Understanding the emergence of postural control in infants is crucial for developmental milestones.
• Postural responses in infants differ significantly from those in adults, necessitating detailed investigation.

Purpose of the Study:

• To investigate the developmental trajectory of postural responses in children before and during the acquisition of independent sitting.
• To compare infant postural responses to those observed in adults.

Main Methods:

• Electromyography (EMG) and kinematic analysis were used to record body movements and muscle activity in response to surface perturbations (translation and rotation).
• Children were categorized as either able to sit independently or not yet able to sit without support.
• Perturbations were applied in directions causing backward and forward body sway.

Main Results:

• Independently sitting children demonstrated consistent muscle activation patterns in ventral hip, trunk, and neck muscles, with inhibition of extensor muscles.
• Backward sway perturbations elicited predictable pelvic rotation as the initial movement, preceding irregular head movements.
• Pre-sitting infants showed less consistent ventral muscle activation, particularly during forward sway perturbations.
• The basic ventral muscle activation pattern in sitting infants showed similarities to adults, while dorsal muscle activation patterns differed.

Conclusions:

• Backward pelvic rotation is a key trigger for postural adjustments in independently sitting children.
• A foundational form of postural adjustment develops in a predetermined manner prior to independent sitting.
• Infant postural control exhibits a basic structure similar to adults, refined by sensory integration and central pattern generators.