Emergence of motor circuit activity

Area of Science:

• Neuroscience
• Developmental Biology
• Computational Neuroscience

Background:

• Ordered neuronal activity patterns can emerge in the developing nervous system without sensory input.
• The embryonic chicken spinal motor circuit, particularly the lateral motor column (LMC), serves as a model to study these emergent patterns.

Purpose of the Study:

• To investigate the molecular and functional basis of early neuronal activity in the developing spinal cord.
• To understand how differential neurotransmitter receptor expression influences motor neuron activity.
• To track the developmental trajectory of neuronal activity from asynchronous to synchronous patterns.

Main Methods:

• Patch-clamp recordings in single medial and lateral LMC neurons.
• Calcium imaging of LMC motor neuron populations.
• Analysis of neurotransmitter receptor subunit and transporter expression (e.g., CHRNA5, CHRNA7, GRIN2A, GRIK1, HTR1A, HTR1B, KCC2).
• Pharmacological inhibition of nicotinic, muscarinic, and GABA-ergic activity.

Main Results:

• Medial and lateral LMC neurons exhibit distinct molecular profiles and subtle differences in activity patterns.
• Inhibition of key neurotransmitter systems significantly impacts early motor circuit activity.
• Neuronal activity transitions from asynchronous and disordered to organized and synchronous during LMC neuron muscle innervation.
• Despite diverse receptor expression, LMC neuron activity patterns show notable similarity.

Conclusions:

• Differential expression of neurotransmitter systems and emergent patterned activity are crucial for developing near-mature locomotor patterns.
• The study elucidates the intrinsic mechanisms driving the formation of functional motor circuits.
• These findings contribute to understanding the developmental basis of coordinated movement.