Posture and locomotion in the rat: independent or interdependent development?

Area of Science:

• Neuroscience
• Developmental Biology
• Motor Control

Background:

• The development of walking and postural control is a complex process involving the maturation of the nervous system.
• In rats, an adult-like walking pattern emerges around postnatal day 15-16 (P15-P16).
• Prior to this, postural control, assessed via EMG activity, is not well-coordinated with the step cycle.

Purpose of the Study:

• To review recent research on the relationship between postural control and walking development in rats.
• To investigate the neuroanatomical and neurophysiological underpinnings of developing postural control.
• To elucidate the role of descending projections and suprasegmental structures in this developmental process.

Main Methods:

• Review of existing neurophysiological studies examining EMG activity in trunk muscles during locomotion.
• Analysis of neuroanatomical data on motoneuronal pools and dendrite bundle formation in postural muscles.
• Consideration of results from spinal transection experiments at P10.

Main Results:

• Adult-like walking patterns in rats develop around P15-P16.
• Accurate postural control emerges after P15-P16, with adult EMG patterns established by P21.
• Motoneuronal pools innervating postural muscles develop conspicuous dendrite bundles around the time adult postural control begins.
• Spinal transection at P10 prevents dendrite bundle development, suggesting dependence on descending projections.

Conclusions:

• The maturation of suprasegmental structures and their spinal projections is essential for the development of postural control.
• Dendrite bundle development in motoneuronal pools is likely dependent on the functional maturation of descending pathways.
• Postural control development continues for 5-6 days after the establishment of adult-like walking patterns, indicating a distinct maturation phase.