Leech heart interneuron network model (Hill et al 2001, 2002)

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We have created a computational model of the timing network that paces the heartbeat of the medicinal leech, Hirudo medicinalis. In the intact nerve cord, segmental oscillators are mutually entrained to the same cycle period. Although experiments have shown that the segmental oscillators are coupled by inhibitory coordinating interneurons, the underlying mechanisms of intersegmental coordination have not yet been elucidated. To help understand this coordination, we have created a simple computational model with two variants: symmetric and asymmetric. See references for more details. Biologically realistic network models with two, six, and eight cells and a tutorial are available at the links to Calabrese's web site below.
1 . Hill AA, Masino MA, Calabrese RL (2002) Model of intersegmental coordination in the leech heartbeat neuronal network. J Neurophysiol 87:1586-602 [PubMed]
2 . Hill AA, Lu J, Masino MA, Olsen OH, Calabrese RL (2001) A model of a segmental oscillator in the leech heartbeat neuronal network. J Comput Neurosci 10:281-302 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Realistic Network;
Brain Region(s)/Organism: Leech;
Cell Type(s): Leech heart interneuron;
Channel(s): I Na,p; I Na,t; I K; I h; I Calcium; I Potassium;
Gap Junctions:
Simulation Environment: GENESIS;
Model Concept(s): Activity Patterns; Bursting; Oscillations; Spatio-temporal Activity Patterns; Tutorial/Teaching; Action Potentials; Invertebrate;
Implementer(s): Hill, Andrew A [aavhill at yahoo.com];
Search NeuronDB for information about:  I Na,p; I Na,t; I K; I h; I Calcium; I Potassium;
// genesis

/* Now deal with the new object
** new class definitions can be added using the 'newclass' command
** Note that classes are simply used for grouping of related elements
** and do not alter the element functionality in any way
** See scheduling (genesis/startup/schedule.g) for an example of class use

newclass	SynGSclass

**                          Example OBJECT TABLE                            **

//	name		data_type	function	class		

object  SynS_object     SynS_type       SynS_f  SynGSclass  device \
        -author         "ron  lab, 3/97 " \
        -actions        INIT PROCESS RESET CHECK SAVE2 RESTORE2  \
        -messages       VOLTAGE 0       1  voltage \
        -readwrite      m_SynS     "modulation factor" \
	-readwrite      A          "A"           \
        -readwrite      B          "B"           \
        -readwrite      C          "C"           \
        -readwrite      D          "D"           \
        -readwrite      E          "E"      \
	-hidden		Ek         "Ek not used " \
	-hidden 	Ik         "Ik not used " \
	-hidden         Gk         "Gk not used " \
	-hidden    	activation "activation not used" \
        -description    "a new object for voltage-dependent modulation " \
                        "of spike-mediated synaptic transmission." \
                        "Modulation is a sigmoidal function of membrane" \
                        "potential given by " \
                        "ModInf=A+B/(1+exp(C*(Vm+D)))" \
                        "E is the time constant"

object	SynG_object	SynG_type	SynG	SynGSclass  device \
	-author 	"ron  lab,3/97 " \
	-messages	VOLTAGE 0       1  voltage \
			CAF     1       1  FastCa  \
                        CAS     2       1  SlowCa  \
                        POSTVOLTAGE 3   1  postvoltage \
        -readwrite      A          "shunts effective Ca current"  \
        -readwrite      B          "buffering parameter "  \
        -readwrite      P          "Ca factor governing transmitter release"  \
        -readwrite      C          "limit parameter(limits release to Gbar)"  \
        -readwrite      R          "release = p^3/(p^3+C)"    \
        -readwrite      Gbar       "maximal conductance" \
        -readwrite      A1         "A1 in Ainf=A1+A2/(1+exp(A3+(Vm+A4)))" \
        -readwrite      A2         "A2" \
        -readwrite      A3         "A3" \
        -readwrite      A4         "A4" \
        -readwrite      A5         "A5 is the time constant" \
	-readonly       Ik         "Ik" \
	-hidden 	activation "activation not used" \
	-description	"A new object specifically for" \
			"graded synaptic inhibition in the leech"

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