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;
//bcell-const.g
/** Used with the terminal branches model **/
/* Units: Millimole, nanoamps, megaohms, microsiemens, milliseconds, 
   nanoFarads, Liters, centimeters */

float PI = 3.14159

float umole	=	1e-6	/* units are umoles and uM */
float mmole	=	1e-3	/* units are mmoles and mM */
int quant	=	1 /* integrate using quantity, not concentration */
int concen	=	0 /* integrate using concentration, not quantity */

/* RM*CM = ~ 35 msec => passive membrane time constant. */
float RI	=	100e-6	/* Mohm-cm, could be 200e-6 */
float RM	=	1e-2	/* Megaohms - cm^2; 5e-2 from Spruston et al, used with increased rhab SA */
float CM	=	1e3	/* nanoFarads/cm^2; 1e3 from Spruston et al. */

float gshunt	=	0.005
float Er	=	-60
float Vinit	=	-60

float gleak	=	250	/* produces ~0.029 uS in rhab (consistent with IKlight)*/
float gna	=	5e5
float g_ih	=	2000	/* produces 25nS in entire cell? */
float pca_p	=	0.1	/* consider 0.2 instead of 0.1*/
float pca_t	=	0.1
float gkca	=	64e3
float gka	=	100e3	/* uS/cm^2; consider 150e3 */
float g_gabaa	=	70e4	/* gamma*(mol/cm^2) */
float g_gabab	=	70e3	/* uS/cm^2 */

float somarad	=	10.4e-4 /* e-4 converts from microns to cm */
float somalen	=	24e-4	/* 24 microns */
int somacyls	=	24 
int somashells	=	2

float rhabrad	=	6.17e-4 
float rhabcorerad=  1.0e-4
float rhablen	=	12e-4
float rhabSA	=	0.000125  /*Assuming 5000 microvilli. 0.08 um radius X 10 um len or 0.08 diam x 5 um len */
float rhabxarea	=	3.14e-8  /* Core cross section assuming 2e-4 dia non-villi portion */
int rhabcyls	=	12
int rhabshells	=	2
/*float rhabvillen	=	5.17e-4  length of microvilli used prior to 08/16/02 */
float rhabvillen	=	10e-4	/* actual length, Eakin et al.*/
/*float rhabvilrad	=	0.1e-4 	 radius of microvil used prior to 08/16/02 */
float rhabvilrad	=	0.04e-4 /* actual radius of microvil, Eakin et al. */
int numvilli	=	5000 		/* number of microvilli */
float shellsize	=	1e-4

float neckrad	=	3e-4	/* 3 microns */
float necklen	=	1e-4	/* 1 micron neck width */
float axonlen	=	100e-4	/* 100 micron length */
/*float axonrada  =       1e-4    1 micron short axis  prior to 08/16/02*/
float axondiama	=	1.5e-4	/* 1.5 micron short axis diameter! */
float axondiamb	=	3e-4	/* 3 micron long axis  diameter!*/
int axonslice	=	4	/* four axon  voltage compartments */
int axoncyls	=	100

float syn_br_rad	=	0.63e-4		/*0.215e-4  for asym*/
float nosyn_br_rad	=	0.63e-4		/*0.93e-4 for asym */
float branchlen1	=	5e-4	/* branch between synapse & axon*/
float branchlen2	=	10e-4	/* terminal branch with synapse*/
int branchcyls		=	15

float Cacyt     =       0.11e-3      /* mM, for ca=0.0100 */
float CaER      =       0.020         /* mM for ca=0.0100 */
float bufcyt    =       0.1497       /* mM for ca=0.0100*/
float bufER     =       2.399           /* mM, for ca=0.0100 */

float Cadif     =       6.0e-9  /* cm^2/msec */
float bufcyttot =       153e-3          /* mM */
float bufERtot  =       12.0            /* mM, 2x previous value */
float buf_kf    =       1e2     /* per mM-msec, from Nowycky et al. and */
float buf_kb    =       0.5     /* per msec, from Blumenfeld et al. */

float init00	=	0.7434	/*  for ca=0.0110 */
float init10	=	0.1615	/*  for ca=0.0110 */
float init01	=	0.0781	/*  for ca=0.0110 */
float init000	=	0.325	/*  for ca=0.0110 */
float init100	=	0.0	/*  for ca=0.0110 */
float init010	=	0.435	/*  for ca=0.0110 */
float init001	=	0.103	/*  for ca=0.0110 */
float init101	=	0.0	/*  for ca=0.0110 */
float init011	=	0.137	/*  for ca=0.0110 */
float init110	=	0.0	/*  for ca=0.0110 */

float maxiicr   =       0.16             /* Units are /msec */
int iicrpower	=	3
float maxcicr	=	0.08
int cicrpower	=	1
float serca     =       0.00047           /* Units are mmole/msec */
float pumppower	=	2
float ERfactor	=	0.185	/*0.185 ratio of ER volume to cyt vol */

float ip3dif    =       2.83e-9 /* cm^2/msec - Allbritton et al. 1992  */
float ip3init   =       0.0e-3  /* */
float ip3degrad =       0.7e-3 /* IP3 degradation - per msec - Allbritton et al. 1992*/

float Rhodtot	=	10000	/* uM*/
float krhoF	=	1e-6	/* per msec */
int duration	=	3000	/* msec*/
float intensity	=	10.0	/* isomerizations per msec */
			/* 0.01 = ND3, 0.1 = ND2, 1.0 = ND1, 10.0 = ND0 */
int lightdelay	=	10	/*msec*/
float deplete_power	=	0.16	/* decrease in mrho effectiveness = 1/ time^deplete_factor */


float RKArrtot	=	30	/* uM */
float Krkf	=	0.5e-3	/* per msec - uM */
float Krkb	=	5.0e-3	/* per msec */
float Krkcat	=	5e-3	/* per msec */

float Gtot	=	1000	/* uM */
float Kgf	=	6e-3	/* per msec - uM */
float Kgb	=	10e-3	/* per msec */
float Kgcat	=	1920e-3	/* per msec */
float Khyd	=	0.0057e-3  /* per msec */

float Kplcf	=	100e-3 /* per uM per msec */
float Kplcb	=	0.2e-3 /* per msec */
float plctot	=	100	/* uM */
float piptot	=	160	/* uM */
float Kpif	=	0.83e-3	/* per uM per msec */
float Kpib	=	0.1e-3	/* per msec */
float Kpicat1   =       10.0e-3   
float Kpicat2	=	6.0e-3  /* per msec */
float Kgap	=	3e-3	/* per msec */

float Gprot_syn	=	100
float plc_syn	=	10
float gabab_kf 	=	0.06	/* modified to produce EC50 of 1.5 uM */
float gabab_kb 	=	0.5
float recept_tot 	=	1.0	/* unitless or uM */
float gabab_gf	=	2.0
float gabab_gb	=	0.5		/* g5 modified to slow down peak curren
t, g4 not significant */
float gabab_gcat =	0.5