Left-Right Locomotor Coordination in Human Neonates.

Area of Science:

• Neuroscience
• Developmental Biology
• Motor Control

Background:

• Terrestrial locomotion relies on coordinated limb muscle activation, with left-right alternation or synchrony.
• Neural mechanisms of interlimb coordination are understood in mammals but less so in human neonates.

Purpose of the Study:

• To investigate interlimb coordination during stepping in human neonates.
• To compare neonatal locomotor network function with mature locomotion and spinal mammalian preparations.

Main Methods:

• Recorded electromyography (EMG) of lower-limb muscles in 46 neonates performing bilateral and unilateral stepping.
• A blocked leg in various positions was used to elicit different coordination patterns.
• Analyzed EMG oscillations, interlimb coordination frequencies, and responses to limb release and load.

Main Results:

• Observed episodes of left-right alternating and synchronous coordination, with variable EMG oscillation frequencies between limbs.
• Identified 2:1 interlimb coordination and activity deletions on the blocked side.
• Found that hip position significantly affected ipsilateral muscle activity, and limb release initiated swing phase with specific muscle bursts.

Conclusions:

• Neonatal locomotor networks function differently from mature networks due to limited cortical control.
• Mechanisms observed share properties with spinal mammalian preparations, including independent pattern generators and sensory feedback.
• Variable interlimb coordination and incomplete sensory modulation highlight the unique characteristics of human neonatal locomotion.