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Modulation of cellular and synaptic variability in the lamprey spinal cord
1Department of Physiology, Development, and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK. djp27@cam.ac.uk
Journal of Neurophysiology
|October 6, 2006
Summary
Substance P modulates cellular and synaptic variability in the lamprey spinal cord. This neuropeptide alters neural network activity by changing the variance of neuronal signaling, offering insights into spinal cord plasticity.
Area of Science:
- Neuroscience
- Cellular Biology
- Synaptic Plasticity
Background:
- Cellular, synaptic, and network variability are crucial but often overlooked aspects of neural function.
- Traditional research has focused on mean neuronal values, neglecting the impact of variance.
- The neuropeptide substance P's role in modulating neural variability remains underexplored.
Purpose of the Study:
- To investigate cellular and synaptic variability in the lamprey spinal cord.
- To determine how the neuropeptide substance P modulates this variability.
- To elucidate the mechanisms underlying substance P's effects on neural network activity.
Main Methods:
- Electrophysiological recordings of cellular and synaptic activity in the lamprey spinal cord.
- Pharmacological manipulations using substance P.
- Analysis of subthreshold depolarizations, spiking, excitatory postsynaptic potentials (EPSPs), and inhibitory postsynaptic potentials (IPSPs).
- Biochemical assays to determine the dependence on protein kinase A, calcium, and NMDA receptors.
- Ultrastructural analysis of synaptic vesicle morphology.
Main Results:
- Cellular and synaptic variability differed across cell types and synapses.
- Substance P reduced the variability of motor neuron activity and excitatory interneuron spiking.
- Substance P modulated the variance of various postsynaptic potentials (PSPs), with both reductions and increases observed.
- The reduction in EPSP variability was dependent on protein kinase A, calcium, and NMDA receptors, suggesting postsynaptic mechanisms.
- Ultrastructural data indicated a potential presynaptic component involving synaptic vesicle diameter variability.
Conclusions:
- Cellular and synaptic variability are distinct and targetable features of neural systems.
- Substance P significantly modulates neural variability in the spinal cord through both postsynaptic and potentially presynaptic mechanisms.
- Modulation of variability represents an additional pathway for spinal cord plasticity, expanding our understanding of neural adaptation.
