Paired turbulence and light effect on calcium increase in Hermissenda (Blackwell 2004)

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Accession:53427
The sea slug Hermissenda learns to associate light and hair cell stimulation, but not when the stimuli are temporally uncorrelated...These issues were addressed using a multi-compartmental computer model of phototransduction, calcium dynamics, and ionic currents of the Hermissenda photoreceptor...simulations show that a potassium leak channel, which closes with an increase in calcium, is required to produce both the untrained LLD and the enhanced LLD due to the decrease in voltage dependent potassium currents.
Reference:
1 . Blackwell KT (2004) Paired turbulence and light do not produce a supralinear calcium increase in Hermissenda. J Comput Neurosci 17:81-99 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell; Electrogenic pump;
Brain Region(s)/Organism:
Cell Type(s): Hermissenda photoreceptor Type B;
Channel(s): I A; I K,leak; I h; I K,Ca; I Sodium; I Calcium; I Potassium;
Gap Junctions:
Receptor(s): GabaA; GabaB; IP3;
Gene(s):
Transmitter(s): Gaba;
Simulation Environment: Chemesis;
Model Concept(s): Temporal Pattern Generation; Invertebrate; Signaling pathways; Calcium dynamics;
Implementer(s): Blackwell, Avrama [avrama at gmu.edu];
Search NeuronDB for information about:  GabaA; GabaB; IP3; I A; I K,leak; I h; I K,Ca; I Sodium; I Calcium; I Potassium; Gaba;
//ryan-func.g CHEMESIS1.0 
// sets up cicr objects and communication between them for ryanodine receptor
// parameters: betaf, betab, gammaf, gammab = l1, l-1, l2, l-2 from Tang & Othmer 
// Units of per uM-sec equal per mM-msec.  Units of per sec - e-3 per msec

function makecicr(path)
   str path
	
   create cicr {path}/x00
   setfield {path}/x00 \
	alpha_state	0 \
	beta_state	0 \
	gamma_state	0 \
	alpha	0 \
	beta	15 \		/* l1 Tang and Ottmer, 15 per sec-uM*/
	gamma	0.8 \		/* l2 Tang and Ottmer 0.8 per sec-uM*/
	conserve	0 \
	xinit		{init00} \
	xmin		0 \
	xmax		1
	
   create cicr {path}/x10
   setfield ^ \
	alpha_state	0 \
	beta_state	1 \
	gamma_state	0 \
	alpha	0 \
	beta	7.6e-3 \	/* L-1 Tang and Ottmer 7.6/ sec = 7.6e-3/msec*/
	gamma	0.8 \		/* L2 Tang and Ottmer */
	conserve	0 \
	xinit		{init10} \
	xmin		0 \
	xmax		1
	
   create cicr {path}/x01
   setfield ^ \
	alpha_state	0 \
	beta_state	0 \
	gamma_state	1 \
	alpha	0 \
	beta	15 \		/* l1 Tang and Ottmer */
	gamma	0.84e-3 \	/* L-2 Tang and Ottmer 0.84/sec = 0.84e-3/msec*/
	conserve	0 \
	xinit		{init01} \
	xmin		0 \
	xmax		1
	
   create cicr {path}/x11
   setfield ^ \
	alpha_state	0 \
	beta_state	1 \
	gamma_state	1 \
	alpha	0 \
	beta	7.6e-3 \	/* L-1 Tan and Ottmer */
	gamma	0.84e-3 \	/* L-2 Tan and Ottmer */
	conserve	1 \
	xinit		{1-init00-init01-init10} \
	xmin		0 \
	xmax		1

addmsg {path}/x10 {path}/x00 BSTATE beta fraction
addmsg {path}/x01 {path}/x00 GSTATE gamma fraction

addmsg {path}/x00 {path}/x10 BSTATE beta previous_state
addmsg {path}/x11 {path}/x10 GSTATE gamma fraction

addmsg {path}/x11 {path}/x01 BSTATE beta fraction
addmsg {path}/x00 {path}/x01 GSTATE gamma previous_state

addmsg {path}/x00 {path}/x11 CONSERVE previous_state
addmsg {path}/x01 {path}/x11 CONSERVE previous_state
addmsg {path}/x10 {path}/x11 CONSERVE previous_state

end

/********************************************************/
// must create ca and er compartments first

function makecicrflux(Capath,erpath,maxcond,expon, unit)
   str Capath,erpath
   float maxcond, unit
   int expon
   
   create cicrflux {Capath}/ryanflux
   setfield {Capath}/ryanflux \
	power {expon} \	/* open fraction = x10^power */
	maxflux {maxcond} \
	units {unit}

/* Messages from cytosolic calcium to ryanodine receptor channel states */
addmsg {Capath} {Capath}/x00 CALCIUM Conc	
addmsg {Capath} {Capath}/x10 CALCIUM Conc
addmsg {Capath} {Capath}/x01 CALCIUM Conc
	
/*Messages to cicr flux  (compute channel permeability) */

addmsg {Capath} {Capath}/ryanflux CONC1 Conc
addmsg {erpath} {Capath}/ryanflux CONC2 Conc
addmsg {Capath}/x10 {Capath}/ryanflux IP3R fraction

/* Messages back to cytosol and er */

addmsg {Capath}/ryanflux {Capath} RXN0MOLES deltaflux1
addmsg {Capath}/ryanflux {erpath} RXN0MOLES deltaflux2

end

/********************************************************************/