Convergent neuromodulation onto a network neuron can have divergent effects at the network level

Nickolas Kintos, Michael P. Nusbaum, Farzan Nadim

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Different neuromodulators often target the same ion channel. When such modulators act on different neuron types, this convergent action can enable a rhythmic network to produce distinct outputs. Less clear are the functional consequences when two neuromodulators influence the same ion channel in the same neuron. We examine the consequences of this seeming redundancy using a mathematical model of the crab gastric mill (chewing) network. This network is activated in vitro by the projection neuron MCN1, which elicits a half-center bursting oscillation between the reciprocally-inhibitory neurons LG and Int1. We focus on two neuropeptides which modulate this network, including a MCN1 neurotransmitter and the hormone crustacean cardioactive peptide (CCAP). Both activate the same voltage-gated current (IMI) in the LG neuron. However, IMI-MCN1, resulting from MCN1 released neuropeptide, has phasic dynamics in its maximal conductance due to LG presynaptic inhibition of MCN1, while IMI-CCAP retains the same maximal conductance in both phases of the gastric mill rhythm. Separation of time scales allows us to produce a 2D model from which phase plane analysis shows that, as in the biological system, IMI-MCN1 and IMI-CCAP primarily influence the durations of opposing phases of this rhythm. Furthermore, IMI-MCN1 influences the rhythmic output in a manner similar to the Int1-to-LG synapse, whereas IMI-CCAP has an influence similar to the LG-to-Int1 synapse. These results show that distinct neuromodulators which target the same voltage-gated ion channel in the same network neuron can nevertheless produce distinct effects at the network level, providing divergent neuromodulator actions on network activity.

Original languageEnglish (US)
Pages (from-to)113-135
Number of pages23
JournalJournal of Computational Neuroscience
Volume40
Issue number2
DOIs
StatePublished - Apr 1 2016

All Science Journal Classification (ASJC) codes

  • Sensory Systems
  • Cognitive Neuroscience
  • Cellular and Molecular Neuroscience

Keywords

  • Central pattern generator
  • Mathematical modeling
  • Neuromodulation
  • Phase plane analysis
  • Stomatogastric ganglion

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