Comodulation of h- And Na¹/K¹ pump currents expands the range of functional bursting in a central pattern generator by navigating between dysfunctional regimes

• Type of Material: Article
• Authors: Parker J Ellingson, Georgia State University; William H Barnett, Georgia State University; Daniel Kueh, Emory University; Alex Vargas, Georgia State University; Ronald Calabrese, Emory University; Gennady S Cymbalyuk, Georgia State University
• Language: English
• Date: 2021-07-28
• Publisher: Society for Neuroscience
• Publication Version: Final Published Version
• Copyright Statement: © 2021 the authors
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1523/JNEUROSCI.0158-21.2021
• Title of Journal or Parent Work: Journal of Neuroscience
• Volume: 41
• Issue: 30
• Start Page: 6468
• End Page: 6483
• Grant/Funding Information: This work was supported by National Institutes of Health Grant 1 R21 NS111355 to G.S.C. and R.L.C.; and Georgia State University Brains and Behavior Fellowship Program to P.J.E. and W.H.B.
• Keywords: leech; Central Pattern Generators; seizure-like oscillations; Sodium-Potassium-Exchanging ATPase; oscillatory networks; Neuropeptides; Computer Simulation; Models, Neurological; neuromodulation; Interneurons; Leeches; Action Potentials; invertebrate; half-center oscillator; Animals
• Research Categories: Biology, Neuroscience

Abstract

Central pattern generators (CPGs), specialized oscillatory neuronal networks controlling rhythmic motor behaviors such as breathing and locomotion, must adjust their patterns of activity to a variable environment and changing behavioral goals. Neuromodulation adjusts these patterns by orchestrating changes in multiple ionic currents. In the medicinal leech, the endogenous neuromodulator myomodulin speeds up the heartbeat CPG by reducing the electrogenic Na1/K1 pump current and increasing h-current in pairs of mutually inhibitory leech heart interneurons (HNs), which form half-center oscillators (HN HCOs). Here we investigate whether the comodulation of two currents could have advantages over a single current in the control of functional bursting patterns of a CPG. We use a conductance-based biophysical model of an HN HCO to explain the experimental effects of myomodulin. We demonstrate that, in the model, comodulation of the Na1/K1 pump current and h-current expands the range of functional bursting activity by avoiding transitions into nonfunctional regimes, such as asymmetric bursting and plateau-containing seizure-like activity. We validate the model by finding parameters that reproduce temporal bursting characteristics matching experimental recordings from HN HCOs under control, three different myomodulin concentrations, and Cs1 treated conditions. The matching cases are located along the border of an asymmetric regime away from the border with more dangerous seizure-like activity. We found a simple comodulation mechanism with an inverse relation between the pump and h-currents makes a good fit of the matching cases and comprises a general mechanism for the robust and flexible control of oscillatory neuronal networks.