Localization of Rhythm Generating Components of the Mammalian Locomotor Central Pattern Generator

Area of Science:

• Neuroscience
• Spinal Cord Research
• Mammalian Locomotion

Background:

• Mammalian locomotion relies on spinal cord central pattern generators (CPGs).
• Identifying specific rhythmogenic interneurons within CPGs remains challenging.
• Previous research focused on genetic identification of CPG components.

Purpose of the Study:

• To identify the specific spinal cord region housing rhythm-generating neurons.
• To investigate the role of medial spinal cord interneurons in locomotion.

Main Methods:

• Focal application of 5-hydroxytryptamine (5-HT) and N-methyl-D-aspartate (NMDA) to the central canal of neonatal mouse spinal cords.
• Inhibition or ablation of neurons in specific spinal cord regions.
• Analysis of fictive locomotion patterns.

Main Results:

• 5-HT and NMDA application to the rostral lumbar central canal rapidly induced fictive locomotion.
• Inhibition of neurons in this medial region disrupted locomotor rhythm.
• Caudal lumbar application required higher drug volumes and had localized effects.

Conclusions:

• Interneurons in the medial laminae of the neonatal mouse spinal cord are necessary and sufficient for locomotor activity.
• This medial region likely contains the rhythm-generating core of the locomotor CPG.