Enhanced Excitability in Hermissenda: modulation by 5-HT (Cai et al 2003)

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Accession:34163
Serotonin (5-HT) applied to the exposed but otherwise intact nervous system results in enhanced excitability of Hermissenda type-B photoreceptors. Several ion currents in the type-B photoreceptors are modulated by 5-HT, including the A-type K+ current (IK,A), sustained Ca2+ current (ICa,S), Ca-dependent K+ current (IK,Ca), and a hyperpolarization-activated inward rectifier current (Ih). In this study,we developed a computational model that reproduces physiological characteristics of type B photoreceptors, e.g. resting membrane potential, dark-adapted spike activity, spike width, and the amplitude difference between somatic and axonal spikes. We then used the model to investigate the contribution of different ion currents modulated by 5-HT to the magnitudes of enhanced excitability produced by 5-HT. See paper for results and more details.
Reference:
1 . Cai Y, Baxter DA, Crow T (2003) Computational study of enhanced excitability in Hermissenda: membrane conductances modulated by 5-HT. J Comput Neurosci 15:105-21 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Hermissenda photoreceptor Type B;
Channel(s): I Na,t; I L high threshold; I N; I A; I K; I h; I K,Ca; I Calcium; I A, slow;
Gap Junctions: Gap junctions;
Receptor(s):
Gene(s):
Transmitter(s): Serotonin;
Simulation Environment: SNNAP;
Model Concept(s): Activity Patterns; Action Potentials; Invertebrate;
Implementer(s): Cai, Yidao;
Search NeuronDB for information about:  I Na,t; I L high threshold; I N; I A; I K; I h; I K,Ca; I Calcium; I A, slow; Serotonin;
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Cai
readme.txt
00note.txt
axona.neu
axona2axonb.es
axonb.neu
axonb2axonc.es
axonc.neu
axonc2term.es
bph.ntw
bph.ntw_genp
bph.ous
bph.ous_bak
bph.ous_genp
bph.ous_mod
bph.ous_Ri
bph.ous_sp
bph.ous_vclamp
bph.ous2
bph.ous3
bph.ous4
bph.smu
bph.trt
bph.trt_casmod
bph.trt_Drmod
bph.trt_Iamod
bph.trt_Ihmod
bph.trt_Ikcamod
bph.trt_light
bph.trt_mixmod
bph.trt_Ri
bph.trt_std
bph.trt_vclamp
bph.trt0
bph_casmod.smu
bph_Drmod.smu
bph_genp.smu
bph_Iamod.smu
bph_Ihmod.smu
bph_Ikcamod.smu
bph_mixmod.smu
bph_Ri.smu
bph_stdmod.smu
ca.A
ca.B
Ca.ion
ca.vdg *
Ca2Ikca.fBR
cat.A
cat.B
cat.vdg
design.txt
Dr.A
Dr.B
Dr.vdg
exp.es
exp1.fnc
exp2.fnc
exp3.fnc
grf.def
Ia.A
Ia.A_bak
Ia.B
Ia.vdg
Ikca.A
Ikca.B
Ikca.vdg *
Ir.A
Ir.vdg
leak.vdg
mv.neu
mv2soma.es
mvleak.vdg
Na.A
Na.B *
Na.vdg
ousgrf.def
simufiles.usd
soma.neu
soma2axona.es
tCa.ion
tca.vdg *
tCa2Ikca.fBR
tcat.vdg *
tDr.vdg
term.neu
term.neu_bak
tIa.vdg
tIkca.vdg *
tIr.vdg
tleak.vdg
tmp.1
tmp.ps
tNa.A
tNa.B
tNa.vdg
treatment.fnc
xaleak.vdg
xbCa.ion *
xbca.vdg *
xbCa2Ikca.fBR
xbcat.vdg *
xbDr.vdg *
xbIa.vdg *
xbIkca.vdg *
xbIr.vdg
xbleak.vdg
xbNa.A *
xbNa.B *
xbNa.vdg *
xcCa.ion *
xcca.vdg *
xcCa2Ikca.fBR
xccat.vdg *
xcDr.vdg *
xcIa.vdg *
xcIkca.vdg *
xcIr.vdg
xcleak.vdg
xcNa.A *
xcNa.B *
xcNa.vdg *
                            
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>    module's name: fnc	>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>----------------------------------------------------------------------->

		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
fnc:		> 	treatment function 	>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>----------------------->----------------------------------------->
>			>					  >
	1 		> f = g * pow(X1, p1) * pow(X2, p2) *  ...
>			>					  >
> ................................................................>
>	60	>g<	> scaling factor
>	30	>g<	> scaling factor
>	4	>g<	> scaling factor
	6	>g<	> scaling factor
	2	>N<	> number of pow(X, p) terms
>----------------------->----------------------------------------->

		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
powxp:		> 	individual function 	>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>----------------------->----------------------------------------->
> Note: 
>	1. "t" is relative to injection starting time
>	2. this section may be repeated N times if N > 1 
>
>----------------------->----------------------------------------->
>			>					  >
>   	1		> type 1, sinewave 
>			>					  >
> ................................................................> 
>  X = k + sin(2 * PI *(t/T + alpha)) 
> ................................................................> 
>	1	>p<	> power factor for X
>	2	>T<	> period, in sec
>	0.	>alpha< > phase lead/delay, in fraction of period
>	0	>k<	> offset value for the waveform
> ................................................................> 
>----------------------->----------------------------------------->
>			>					  >
>	2		> type 2, triangular 
>			>					  >
> ................................................................> 
>	x = alpha + t/T
>	x = x - INT(x)		# INT(x) is the integer portion of X
> 	if (x >= 0 && x < 0.5) X = (k2 - k1) * x * 2 + k1;
> 	if (x >= 0.5 && x < 1.0) X = k2 - (k2 - k1) * (x-0.5) * 2;
> ................................................................> 
>	2	>p<	> power factor for X
>	4.0	>T<	> period, in sec
>	0.5	>alpha< > phase lead/delay, in fraction of period
>	-1	>k1<	> minimum value of X, -1, or 0
>	1	>k2<	> maximum value of X, 0 or 1
>----------------------->----------------------------------------->
>			>					  >
>	3		> type 3, linear ramp
>			>					  >
> ................................................................> 
>	if (t <= t1) X = k1;
> 	if (t > t1 && t < t2) X = (k2 - k1) * (t-t1)/(t2-t1) + k1;
> 	if (x >= t2) X = k2;
> ................................................................>
>	1	>p<	> power factor for X
>	0.5	>t1<	> time ramp starts, in sec
>	7.5	>t2<	> time ramp ends, in sec
>	-1	>k1<	> starting value of X, -1, 0 or 1
>	1	>k2<	> ending value of X, -1, 0 or 1
>----------------------->----------------------------------------->
>			>					  >
>	4		> type 4, square wave
>			>					  >
> ................................................................> 
>	x = alpha + t/T
>	x = x - INT(x)		# INT(x) is the integer portion of X
> 	if (x >= 0 && x < 0.5) X = k2;	# positive half comes first
> 	if (x >= 0.5 && x < 1.0) X = k1;
> ................................................................> 
>	1	>p<	> power factor for X
>	4	>T<	> period, in sec
>	0	>alpha< > phase lead/delay, in fraction of period
>	-1	>k1<	> minimum value of X, -1, or 0
>	1	>k2<	> maximum value of X, 0 or 1
>----------------------->----------------------------------------->
>			>					  >
	5		> type 5, exponential function
>			>					  >
> ................................................................> 
>	X = k1 + k2 * exp((t-t0)*u(t-t0)/tau)
>  i.e.
>	if (t < t0) X = k1 + k2;
>	else X = k1 + k2 * exp((t-t0)/tau)
> ................................................................> 
	1	>p<	> power factor for X
	0	>t0<	> delay time, in sec
	-0.5	>tau<   > time constant, in sec
	1	>k1<	> -1 to 1
	-1	>k2<	> -1 to 1
>----------------------->----------------------------------------->
	5		> type 5, exponential function
> ................................................................> 
	1	>p<	> power factor for X
	0	>t0<	> delay time, in sec
	-0.24	>tau<   > time constant, in sec
	0	>k1<	> -1 to 1
	1	>k2<	> -1 to 1
>----------------------->----------------------------------------->


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