Rendering of the source text

<?xml version="1.0"?>
<!--  FILE :  butera_model_1999.xml

CREATED :  9th May 2002

LAST MODIFIED : 20th April 2005

AUTHOR :  Catherine Lloyd
          Bioengineering Institute
          The University of Auckland
          
MODEL STATUS :  This model conforms to the CellML 1.0 Specification released on
10th August 2001, and the 16/01/2002 CellML Metadata 1.0 Specification.

DESCRIPTION :  This file contains a CellML description of Butera et al's first 1999 mathematical model of respiratory rhythm generation in the pre-Botzinger complex in bursting pacemaker neurons.

CHANGES:  
  18/07/2002 - CML - Added more metadata.
  09/04/2003 - AAC - Added publication date information.
  20/04/2005 - PJV - Made MathML id's unique  
--><model xmlns="http://www.cellml.org/cellml/1.0#" xmlns:cmeta="http://www.cellml.org/metadata/1.0#" cmeta:id="butera_1999" name="butera_1999">

<documentation xmlns="http://cellml.org/tmp-documentation">
<article>
  <articleinfo>
  <title>Models Of Respiratory Rhythm Generation In The Pre-Botzinger Complex. I. Bursting Pacemaker Neurons</title>
  <author>
    <firstname>Catherine</firstname>
          <surname>Lloyd</surname>
    <affiliation>
      <shortaffil>Auckland Bioengineering Institute, The University of Auckland</shortaffil>
    </affiliation>
  </author>
</articleinfo>
  <section id="sec_status">
    <title>Model Status</title>
    <para>
          This CellML model runs in OpenCell and COR to reproduce the published results (Figure 4 A3 where E_L = -57.5 mv).  Please note that the model has to be run for a duration of 10000 ms with a step size of 0.01 ms and a high point density of 100000 points/graph.  This model represents model 1 from the published paper (which does not include a slow potassium current).
          </para>
  </section>
  <sect1 id="sec_structure">
<title>Model Structure</title>

<para>
ABSTRACT: A network of oscillatory bursting neurons with excitatory coupling is hypothesized to define the primary kernel for respiratory rhythm generation in the pre-Botzinger complex (pre-BotC) in mammals. Two minimal models of these neurons are proposed. In model 1, bursting arises via fast activation and slow inactivation of a persistent Na+ current INaP-h. In model 2, bursting arises via a fast-activating persistent Na+ current INaP and slow activation of a K+ current IKS. In both models, action potentials are generated via fast Na+ and K+ currents. The two models have few differences in parameters to facilitate a rigorous comparison of the two different burst-generating mechanisms. Both models are consistent with many of the dynamic features of electrophysiological recordings from pre-BotC oscillatory bursting neurons in vitro, including voltage-dependent activity modes (silence, bursting, and beating), a voltage-dependent burst frequency that can vary from 0.05 to &gt;1 Hz, and a decaying spike frequency during bursting. These results are robust and persist across a wide range of parameter values for both models. However, the dynamics of model 1 are more consistent with experimental data in that the burst duration decreases as the baseline membrane potential is depolarized and the model has a relatively flat membrane potential trajectory during the interburst interval. We propose several experimental tests to demonstrate the validity of either model and to differentiate between the two mechanisms.
</para>

<para>
The complete original paper reference is cited below:
</para>

<para>
Models of Respiratory Rhythm Generation in the Pre-Botzinger Complex. I. Bursting Pacemaker Neurons, Robert J. Butera, Jr., John Rinzel and Jeffrey C. Smith, 1999, <emphasis>Journal of Neurophysiology</emphasis>, 81, 382-397. <ulink url="http://www.ncbi.nlm.nih.gov/pubmed/10400966">PubMed ID: 10400966</ulink> 
</para>

<informalfigure float="0" id="fig_cell_diagram1">
<mediaobject>
  <imageobject>
    <objectinfo>
      <title>diagram of the first model</title>
    </objectinfo>
    <imagedata fileref="butera_1999a.png"/>
  </imageobject>
</mediaobject>
<caption>The first mathematical model is based on a single-compartment Hodgkin-Huxley type formalism.  It is composed of five ionic currents across the plasma membrane: a fast sodium current, I<subscript>Na</subscript>; a delayed rectifier potassium current, I<subscript>K</subscript>; a persistent sodium current,  I<subscript>NaP</subscript>; a passive leakage current, I<subscript>L</subscript>; and a tonic current, I<subscript>tonic_e</subscript> (although this last current is considered to be inactive in these models).</caption>
</informalfigure>

<informalfigure float="0" id="fig_cell_diagram2">
<mediaobject>
  <imageobject>
    <objectinfo>
      <title>diagram of the first model</title>
    </objectinfo>
    <imagedata fileref="butera_1999b.png"/>
  </imageobject>
</mediaobject>
<caption>The second model appears identical to the first except with the addition of a slow K<superscript>+</superscript> current, I<subscript>KS</subscript>.  (The removal of the inactivation term "h" from I<subscript>NaP</subscript> is not visible in the model diagram.)</caption>
</informalfigure>

</sect1>
</article>
</documentation>
  
  
 
  
  <units name="millisecond">
    <unit prefix="milli" units="second"/>
  </units>
  
  <units name="millivolt">
    <unit prefix="milli" units="volt"/>
  </units>
  
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    <unit prefix="nano" units="ampere"/>
  </units>
  
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    <variable name="i_L" public_interface="in" units="picoA"/>
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    <variable initial_value="-5.0" name="sigma_m" units="millivolt"/>
     
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    <variable name="time" private_interface="out" public_interface="in" units="millisecond"/>
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    <variable name="time" private_interface="out" public_interface="in" units="millisecond"/>
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    <variable name="E_Na" public_interface="in" units="millivolt"/>         
    
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      <component_ref component="potassium_current">
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    <map_variables variable_1="i_Na" variable_2="i_Na"/>
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    <map_variables variable_1="V" variable_2="V"/>
    <map_variables variable_1="i_K" variable_2="i_K"/>
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  <connection>
    <map_components component_1="persistent_sodium_current" component_2="membrane"/>
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  </connection>
  
  <connection>
    <map_components component_1="leakage_current" component_2="membrane"/>
    <map_variables variable_1="V" variable_2="V"/>
    <map_variables variable_1="i_L" variable_2="i_L"/>
  </connection>
  
  <connection>
    <map_components component_1="tonic_current" component_2="membrane"/>
    <map_variables variable_1="V" variable_2="V"/>
    <map_variables variable_1="i_tonic_e" variable_2="i_tonic_e"/>
  </connection>
  
  <connection>
    <map_components component_1="fast_sodium_current" component_2="persistent_sodium_current"/>
    <map_variables variable_1="E_Na" variable_2="E_Na"/>
  </connection>
  
  <connection>
    <map_components component_1="fast_sodium_current" component_2="fast_sodium_current_m_gate"/>
    <map_variables variable_1="m_infinity" variable_2="m_infinity"/>
    <map_variables variable_1="V" variable_2="V"/>
  </connection>
  
  <connection>
    <map_components component_1="fast_sodium_current" component_2="fast_sodium_current_n_gate"/>
    <map_variables variable_1="n" variable_2="n"/>
    <map_variables variable_1="V" variable_2="V"/>
    <map_variables variable_1="time" variable_2="time"/>
  </connection>
  
  <connection>
    <map_components component_1="potassium_current" component_2="potassium_current_n_gate"/>
    <map_variables variable_1="n" variable_2="n"/>
    <map_variables variable_1="V" variable_2="V"/>
    <map_variables variable_1="time" variable_2="time"/>
  </connection>
  
  <connection>
    <map_components component_1="persistent_sodium_current" component_2="persistent_sodium_current_m_gate"/>
    <map_variables variable_1="m_infinity" variable_2="m_infinity"/>
    <map_variables variable_1="V" variable_2="V"/>
  </connection>
  
  <connection>
    <map_components component_1="persistent_sodium_current" component_2="persistent_sodium_current_h_gate"/>
    <map_variables variable_1="h" variable_2="h"/>
    <map_variables variable_1="V" variable_2="V"/>
    <map_variables variable_1="time" variable_2="time"/>
  </connection>
  
  
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