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]
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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;
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
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axona2axonb.es
axonb.neu
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ca.A
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Ca.ion
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Ca2Ikca.fBR
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design.txt
Dr.A
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Dr.vdg
exp.es
exp1.fnc
exp2.fnc
exp3.fnc
grf.def
Ia.A
Ia.A_bak
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Ia.vdg
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Ikca.vdg *
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Ir.vdg
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Na.vdg
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tCa.ion
tca.vdg *
tCa2Ikca.fBR
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tmp.ps
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xbNa.B *
xbNa.vdg *
xcCa.ion *
xcca.vdg *
xcCa2Ikca.fBR
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xcIa.vdg *
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xcNa.B *
xcNa.vdg *
                            
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>    module's name: A		>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>


		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
A:		> 	Activation function (time constant method)	>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>------------------------------->--------------------------------------->
>				>					>
>	1			>	A = ssA			(1)	>
>				>					>
>------------------------------->--------------------------------------->
	2			>	        ssA - A			>
	0.25	>IV<		>	dA/dt= ------------	(2)	>
				>	           tA			>
>------------------------------->--------------------------------------->

		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
ssA:		> 	Steady state value for activation		>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>----------------------->------------------------------------------------------>
>	1		>			1			       >
>	-35	>h<	>	ssA = --------------------		(1)    >
>	20.0	>s<	>		+-	     -+ p		       >
>	1	>p<	>		|     (h-V)/s |			       >
			>		|1 + e        |			       >
			>		+-	     -+			       >
	1
	-35	>h<
	20	>s<
	1	>h<
			>						       >
>----------------------->------------------------------------------------------>
>	2		>		   1 - An			       >
>	0.0001	>An<	>	ssA = -------------------- + An		       >
>	0.0002	>h<	>		+-	     -+ p		       >
>	0.0003	>s<	>		|     (h-V)/s |			(2)    >
>	0.00004	>p<	>		|1 + e        |			       >
>			>		+-	     -+			       >
>----------------------->------------------------------------------------------>


		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
tA:		> 	Time constant for activation			>	
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>----------------------->------------------------------------------------------>
>			>						       >
>	1		> tA = tx					    (1)>
>	.030	>tx<	>						       >
>----------------------->------------------------------------------------------>
>	2		>	  tx -tn				       >
>         .576  >tx<	> tA = -------------------- + tn	            (2)>
>	.0184	>tn<	>	+-	     -+ p			       >
>	105.7	>h<	>	|     (V-h)/s |				       >
>	-53.01>s<	>	|1 + e        |				       >
>	1	>p<	>	+-	     -+				       >
>			>						       >

	2
	1.96	>tx<
	0.31	>tn<
	-33	>h<
	40	>s<
	1	>p<
>----------------------->------------------------------------------------------>