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BMC Neuroscience

, 13:P171 | Cite as

Analysis of input-output relationships of CPG elements and their contributions to rhythmic output

  • Terrence Michael WrightJr
  • Brian Mulloney
  • Ronald L Calabrese
Open Access
Poster presentation
  • 759 Downloads

Keywords

Input Pattern Synaptic Input Dynamic Clamp Stereotyped Motor Metachronal Wave 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.
We use the dynamic clamp technique [1] to explore how synaptic input patterns affect motor output (see Figure 1A). We show that leech motor neuron intrinsic properties make a contribution to their output phasing. Then, we show that leech motor neurons receiving the same complement of synaptic inputs can still be organized into a coordinated motor pattern given that a gradient of synaptic strengths exists and that the premotor interneurons fire at different times [2]. In both of these cases, measuring motor neuron responses provides a direct assay for how premotor input patterns produce stereotyped motor output. We are currently extending this analysis to the crayfish swimmeret system, a system in which four segmental oscillators are interconnected by coordinating interneurons to produce a metachronal wave of swimmeret movements [3]. In this system, ascending (ASC) and descending (DSC) coordinating interneurons (see Figure 1B) encode salient features about the activity pattern of their home segment and are exported (via spikes) to other segmental oscillators. Interestingly, when the system is driven across periods by different concentrations of neuromodulators, the number of spikes of a given coordinating interneuron remains constant although their duty cycles change. We are currently building a single-compartment, conductance-based model of the ASC and DSC coordinating neurons, with the goal of understanding how these coordinating neurons encode information in their home modules and how this encoding can be modulated when the swimmeret system is driven at different periods.
Figure 1

Circuit diagrams and rhythmic motor output from the leech heartbeat central pattern generator (A) and the crayfish swimmeret system (B). A, left: Heart (HE) motor neurons in segments 8 and 12 both receive synaptic input from premotor hear (HN) interneurons located in segments 3,4,6 and 7, which sculpt stereotyped motor output as shown in the simultaneous extracellular recordings of HE motor neurons in segments 8 and 12, which illustrate the peristaltic motor phase progression (right panel). B, left: circuit diagram for the independent oscillator in segment 4 (A4) driving PS4 motor activity observed in the extracellular recordings (right panel; Return stroke [RS(4)] activity not shown). Coordinating interneurons ASC and DSC in A4 encode information that is delivered to an interneuron (C1) in segments 3 (ASC) and 5 (DSC), resulting in the stereotyped rear-to-front activity pattern observed across segments 5,4 and 3 (right panel).

References

  1. 1.
    Sharp AA, O’neil MB, Abbott LF, Marder E: Dynamic clamp: artificial conductances in biological neurons. Trends Neurosci. 1993, 16 (10): 389-94. 10.1016/0166-2236(93)90004-6.CrossRefPubMedGoogle Scholar
  2. 2.
    Wright TM, Calabrese RL: Patterns of presynaptic activity interact to produce motor output. J Neurosci. 2011, 31 (48): 17555-71. 10.1523/JNEUROSCI.4723-11.2011.PubMedCentralCrossRefPubMedGoogle Scholar
  3. 3.
    Smarandache-Wellmann C, Mulloney B: Neurobiology of the crayfish swimmeret system. Prog Neurobiol. 2012, 96 (2): 242-67. 10.1016/j.pneurobio.2012.01.002.PubMedCentralCrossRefPubMedGoogle Scholar

Copyright information

© Wright et al; licensee BioMed Central Ltd. 2012

This article is published under license to BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Authors and Affiliations

  • Terrence Michael WrightJr
    • 1
    • 2
  • Brian Mulloney
    • 2
  • Ronald L Calabrese
    • 1
  1. 1.Department of BiologyEmory UniversityAtlantaUSA
  2. 2.Department of Neurobiology, Physiology and BehaviorUniversity of California, Davis, CADavisUSA

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