Developmental differences in neuromodulation and synaptic properties in the lamprey spinal cord

Area of Science:

• Neuroscience
• Developmental Biology
• Neurophysiology

Background:

• Spinal cord functional properties change during development to meet evolving behavioral needs.
• Neuromodulation plays a critical role in adapting motor outputs.
• Substance P is a key neuromodulator with known effects in adult lamprey spinal cords.

Purpose of the Study:

• To investigate developmental differences in spinal cord plasticity.
• To compare the neuromodulatory effects of substance P in larval versus adult lamprey spinal cords.
• To elucidate the synaptic mechanisms underlying these developmental changes.

Main Methods:

• Comparison of substance P effects in larval and premigratory adult lamprey spinal cords.
• Electrophysiological recordings of excitatory and inhibitory postsynaptic potentials (EPSPs and IPSPs).
• Assessment of N-methyl-d-aspartate (NMDA) receptor contributions to synaptic transmission.

Main Results:

• Substance P's neuromodulatory effects were significantly reduced in larvae compared to adults.
• Larval spinal cords exhibited reduced excitatory synaptic transmission (EPSPs) with a diminished NMDA component.
• Larval spinal cords showed increased inhibitory synaptic transmission (IPSPs), which counteracted substance P's effects.

Conclusions:

• Developmental changes in both excitatory and inhibitory synaptic transmission underlie altered spinal cord plasticity in lampreys.
• Reduced NMDA receptor function and increased inhibition contribute to the diminished neuromodulatory effects of substance P in larvae.
• These synaptic alterations are crucial for adapting motor outputs during spinal cord development.