Locomotor-like activity generated by the neonatal mouse spinal cord

Area of Science:

• Neuroscience
• Developmental Biology
• Motor Control

Background:

• Locomotion is a complex motor behavior essential for survival.
• Understanding the neural circuits controlling locomotion is a key area in neuroscience.
• The neonatal mammalian spinal cord provides a valuable in vitro model for studying fundamental mechanisms of motor pattern generation.

Purpose of the Study:

• To investigate the generation and characteristics of locomotor-like activity in the isolated neonatal mouse spinal cord.
• To explore the underlying neural mechanisms, including potential gradients of excitability and the role of specific neurotransmitter systems.
• To compare findings with existing models of vertebrate locomotion.

Main Methods:

• In vitro electrophysiological recordings and calcium imaging of motoneuron activity in neonatal mouse spinal cord preparations.
• Application of dorsal root stimulation and pharmacological agents to evoke and modulate locomotor-like activity.
• Analysis of spatio-temporal patterns of neural activity to infer network dynamics.

Main Results:

• Locomotor-like activity was reliably generated in vitro, either spontaneously or evoked by stimuli/drugs.
• Calcium imaging revealed a rostrocaudally propagating wave of motoneuron activity in lumbar and sacral segments.
• The data suggest that left/right reciprocal inhibition and NMDA-mediated oscillations are not critical for rhythmogenesis in this model.

Conclusions:

• The neonatal mouse spinal cord in vitro exhibits robust locomotor-like activity with a distinct rostrocaudal propagation.
• A rostrocaudal gradient of excitability is hypothesized to underlie the observed spatio-temporal activity pattern.
• These findings contribute to understanding the basic principles of spinal cord motor control and vertebrate locomotion.