Additional weight influences the reaching behavior of low-risk preterm infants

Area of Science:

• Developmental neuroscience
• Infant motor control
• Biomechanics

Background:

• Preterm infants often exhibit motor delays compared to full-term infants.
• Understanding the impact of external forces on infant motor development is crucial for early intervention.
• Reaching behavior is a key indicator of sensorimotor development in infants.

Purpose of the Study:

• To investigate how additional limb weight influences the reaching behavior of preterm infants.
• To compare the reaching kinematics of preterm and full-term infants under a weight-loading condition.
• To identify specific changes in movement patterns and grasp success associated with added weight in preterm infants.

Main Methods:

• Nine low-risk preterm and 10 full-term infants (5-7 months corrected age) participated.
• Infants performed reaching tasks towards a toy under two conditions: baseline and with a weighted bracelet (20% of upper limb mass).
• Reaching kinematics, including straightness index, mean velocity, movement units, and grasp success, were analyzed.

Main Results:

• Additional weight reduced reaching straightness and increased movement velocity in preterm infants.
• Unsuccessful grasps increased in preterm infants at 5 and 7 months with added weight.
• Preterm infants demonstrated fewer movement units and fewer unsuccessful grasps at 6 months compared to full-term infants.

Conclusions:

• Weight disturbances significantly alter the intrinsic dynamics of reaching movements in preterm infants.
• These findings highlight the sensitivity of preterm infant motor control to external perturbations.
• The study suggests that altered biomechanical conditions impact motor learning and execution in early development.