Interactions between multiple rhythm generators produce complex patterns of oscillation in the developing rat spinal...

Area of Science:

• Neuroscience
• Developmental Biology
• Computational Neuroscience

Background:

• Early spinal cord development involves the formation of neural networks generating rhythmic activity.
• Understanding the organization of these rhythm generators is crucial for comprehending motor control and development.

Purpose of the Study:

• To investigate the spatiotemporal patterns of rhythmic activity in embryonic and neonatal rat spinal cord slices.
• To determine the distribution and organization of neural networks responsible for generating coordinated rhythmic activity.

Main Methods:

• Utilized voltage-imaging techniques with the voltage-sensitive dye RH414 and a photodiode array to record neural activity in transverse spinal cord slices.
• Measured spontaneous voltage oscillations (3 Hz) and correlated them with extracellular field potentials.
• Examined the effects of cobalt (a Ca(2+) channel blocker) and sectioning of slices to assess network properties.

Main Results:

• Observed spontaneous 3 Hz voltage oscillations dependent on Ca(2+) influx.
• Rhythm generation was found to be distributed throughout lumbar spinal cord slices, with larger amplitudes in lateral regions.
• Slices, even when fragmented, maintained oscillations, indicating a lack of dependence on long-range projections.
• Neonatal rat spinal cord slices showed complex spatiotemporal patterns with alternating depolarizations between lateral and medial regions within each cord half.

Conclusions:

• Rhythm-generating networks are widely distributed within the transverse lumbar spinal cord.
• The coordinated rhythmic activity exhibits complex spatiotemporal patterns, with intrinsic pathways on each side of the cord coordinating medial-lateral activity.
• These findings provide insights into the early development of neural circuits underlying rhythmic motor functions.