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Serotonin modulates axo-axonal coupling between neurons critical for learning in the leech
Brenda L Moss1, Abby D Fuller, Christie L Sahley
1Neuroscience Group, Division of Basic Biomedical Sciences, University of South Dakota School of Medicine, Vermillion, 57069, USA.
Journal of Neurophysiology
|July 1, 2005
Summary
Serotonin alters leech neural networks by modulating electrical synapses between S cells. This neurotransmitter affects how nerve signals propagate, influencing sensitization during body shortening.
Area of Science:
- Neuroscience
- Cellular Neuroscience
- Neurophysiology
Background:
- S cells form a crucial electrically coupled neuronal network in the leech central nervous system (CNS).
- This network is vital for sensitization during whole-body shortening behaviors.
- Serotonin is known to modulate neural activity patterns within this network.
Purpose of the Study:
- To investigate whether serotonin modulates the electrical synapses between leech S cells.
- To understand the impact of serotonin on action potential (AP) propagation across these synapses.
Main Methods:
- Studied AP propagation in a two-ganglion leech CNS preparation containing an S-cell electrical synapse.
- Utilized suction electrodes for stimulating and recording S-cell activity.
- Applied octanol as a gap junction inhibitor and serotonin to assess synaptic modulation.
Main Results:
- Octanol increased AP latency and blocked propagation at higher concentrations, confirming its effect on electrical synapses.
- Serotonin increased AP latency across the electrical synapse, indicating reduced coupling between S cells.
- Serotonin's effect was bidirectional and amplified with more synapses, and it modulated AP frequency in computational models.
Conclusions:
- Serotonergic modulation of S-cell electrical synapses likely contributes to altered network activity patterns.
- This modulation may play a role in the neural mechanisms underlying sensitization in leeches.