Episodic rhythmicity is generated by a distributed neural network in the developing mammalian spinal cord

Area of Science:

• Neuroscience
• Spinal Cord Research
• Motor Control

Background:

• Spinal circuits generate rhythmic motor output for locomotion.
• Mechanisms underlying episodic locomotor behaviors are not fully understood.

Purpose of the Study:

• Investigate dopamine-induced episodic rhythms in isolated neonatal mouse spinal cords.
• Elucidate the neural network mechanisms responsible for these episodic behaviors.

Main Methods:

• Used isolated neonatal mouse spinal cord preparations.
• Induced episodic rhythms using dopamine.
• Performed electrical stimulation of dorsal roots and spinal cord transections/lesions.
• Recorded neural activity in spinal cord segments and axons.

Main Results:

• Episodic rhythms were mostly synchronous and rostro-caudally propagating.
• Dorsal root stimulation entrained rhythms, indicating afferent control.
• Rhythmicity persisted in isolated segments after transection or ventrolateral funiculus (VLF) lesions.
• Activity was independent of cholinergic, GABAergic, or dorsal inhibitory circuits.

Conclusions:

• A flexibly coupled, distributed spinal interneuron network underlies episodic rhythmicity.
• The ventrolateral funiculus (VLF)-coupled networks play a role.
• Findings provide a basis for understanding spinal circuit modulation in motor output diversity.