Currents contributing to decision making in neurons B31-B32 of Aplysia (Hurwitz et al. 2008)

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Accession:116606
"Biophysical properties of neurons contributing to the ability of an animal to decide whether or not to respond were examined. B31/B32, two pairs of bilaterally symmetrical Aplysia neurons, are major participants in deciding to initiate a buccal motor program, the neural correlate of a consummatory feeding response. B31/B32 respond to an adequate stimulus after a delay, during which time additional stimuli influence the decision to respond. B31/B32 then respond with a ramp depolarization followed by a sustained soma depolarization and axon spiking that is the expression of a commitment to respond to food. Four currents contributing to decision making in B31/B32 were characterized, and their functional effects were determined, in current- and voltage-clamp experiments and with simulations. ... Hodgkin-Huxley kinetic analyses were performed on the outward currents. Simulations using equations from these analyses showed that IK-V and IK-A slow the ramp depolarization preceding the sustained depolarization. The three outward currents contribute to braking the B31/B32 depolarization and keeping the sustained depolarization at a constant voltage. The currents identified are sufficient to explain the properties of B31/B32 that play a role in generating the decision to feed."
Reference:
1 . Hurwitz I, Ophir A, Korngreen A, Koester J, Susswein AJ (2008) Currents contributing to decision making in neurons B31/B32 of Aplysia. J Neurophysiol 99:814-30 [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: Aplysia;
Cell Type(s): Aplysia B31/B32 neuron;
Channel(s): I Na,t; I A; I K;
Gap Junctions:
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: SNNAP;
Model Concept(s): Action Selection/Decision Making;
Implementer(s):
Search NeuronDB for information about:  I Na,t; I A; I K;
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hurwitzEtAl2008
with_all_currents_fast_stimulus
B_B63_K.a *
B_B63_K.b *
B_B63_Na.A *
B_B63_Na.B *
b31_axon.neu *
B31_axon_2_Soma.es *
b31_axon_K.vdg *
b31_axon_K2.vdg *
b31_axon_leak.vdg *
b31_axon_Na.vdg *
b31_leak_fixed.vdg *
b31_leak_only.neu *
b31_soma_K1.A *
b31_soma_K1.B *
b31_soma_K1.vdg *
b31_soma_K2.A *
b31_soma_K2.B *
b31_soma_K2.vdg *
b31_soma_K3.A *
b31_soma_K3.B *
b31_soma_K3.vdg *
b31_with_axon.ntw *
b31_with_axon.ous
b31_with_axon.ous.mnu
b31_with_axon.smu
b31_with_axon.smu.exec
b31_with_axon.smu.hmn
b31_with_axon.smu.ing
b31_with_axon.trt
b31_with_axon_vc.trt *
b31_with_axon_with_I_del.ous *
ousgrf.def *
simufiles.usd
                            
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>    module's name: B		>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

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

		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
B:		> 	Inactivation function (time constant method)	>
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>------------------------------->--------------------------------------->
>				>					>
>	1			>	B = ssB			(1)	>
>				>					>
>------------------------------->--------------------------------------->
	2			>	        ssB - B			>
	-1.0	>IV<		>	dB/dt= ------------	(2)	>
				>	           tB			>
>------------------------------->--------------------------------------->



		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
ssB:		> 	Steady state value for activation		>	
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>----------------------->------------------------------------------------------>
	1		>			1			       >
	-30.0	>h<	>	ssB = --------------------		(1)    >
	11.0	>s<	>		+-	     -+ p	  	       >
	1.0	>p<	>		|     (V-h)/s |			       >
			>		|1 + e        |			       >
			>		+-	     -+			       >
			>						       >
>----------------------->------------------------------------------------------>
>	2		>		   1 - Bn			       >
>	0.15   >.15 Bn<	>	ssB = -------------------- + Bn		       >
>      -16.4    >-7.4 h<	>		+-	     -+ p		       >
>	1.5	>1.5 s<	>		|     (V-h)/s |			(2)    >
>	2	  >2 p<	>		|1 + e        |			       >
>			>		+-	     -+			       >
>----------------------->------------------------------------------------------>


		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
tB:		> 	Time constant for activation			>	
		>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

>----------------------->------------------------------------------------------>
>			>						       >
>	1		> tB = tx					    (1)>
>	xxxx.xx	>tx<	>						       >
>----------------------->------------------------------------------------------>
>	2		>	  tx -tn				       >
>	0.04	>.2 tx<	> tB = -------------------- + tn	            (2)>
>	0.02	>.02 tn<	>	+-	     -+ p			       >
>	-10.0	>-15 h<	>	|     (V-h)/s |				       >
>	1.0	>8.3 s<	>	|1 + e        |				       >
>	1.0	>1 p<	>	+-	     -+				       >
>			>						       >
>----------------------->------------------------------------------------------>
	3		>	 		tx -tn			       >
	0.33	>tx<	> tB = ----------------------------------- + tn     (3)>
	0.0080	>tn<	>	+-	     -+p1 +-	       -+p2	       >
	-56.0	>h1<	>	|   (V-h1)/s1 |	  |   (V-h2)/s2 |	       >
	-16.0	>s1<	>	|1+e          |	  |1+e          |	       >
	1.0	>p1<	>	+-	     -+	  +-	       -+	       >
	-80.0	>h2<	>						       >
	70.0	>s2<	>						       >
	1.0	>p2<	>						       >
>----------------------->------------------------------------------------------>
>			>	  +--			      -+	       >
>	4		>	  |   1 - rtn		       |	       >
>	xxx.xx	>tx<	> tB = tx | -------------------- + rtn |            (4)>
>	xxx.xx	>rtn<	>	  | +-	          -+ p	       |	       >
>	xxx.xx	>h<	>	  | |     (V-h)/s  |	       |	       >
>	xxx.xx	>s<	>	  | |1 + e         |	       |	       >
>	x	>p<	>	  | +-	          -+           |	       >
>			>	  +-- 			      -+	       >
>			>						       >
>----------------------->------------------------------------------------------>
>			>	+--			                 -+    >
>	5		>	| 	1 - rtn	 	                  |    >
>	xxx.xx	>tx<	> tB=tx | ---------------------------------- +rtn | (5)>
>	xxx.xx	>rtn<	>	| +-	      -+p1+-	      -+p2        |    >
>	xxx.xx	>h1<	>	| |   (V-h1)/s1|  |   (V-h2)/s2|          |    >
>	xxx.xx	>s1<	>	| |1+e         |  |1+e         |          |    >
>	x	>p1<	>	| +-	      -+  +-	      -+          |    >
>	xxx.xx	>h2<	>	+-- 			   	         -+    >
>	xx.xx	>s2<	>						       >
>	x	>p2<	>						       >
>----------------------->------------------------------------------------------>



> Ligand
> -------
> ssB is the steady-stae value of activation and tB is its time constant.
> h's are half parameters, s's are shape parameters and p's are values of the 
  exponents.
> Bn is the minimal value of activation.
> tx is the maximal value of the time constant and tn is its minimal value.
> rtn = tn/tx

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