Striatal Spiny Projection Neuron, inhibition enhances spatial specificity (Dorman et al 2018)

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We use a computational model of a striatal spiny projection neuron to investigate dendritic spine calcium dynamics in response to spatiotemporal patterns of synaptic inputs. We show that spine calcium elevation is stimulus-specific, with supralinear calcium elevation in cooperatively stimulated spines. Intermediate calcium elevation occurs in neighboring non-stimulated dendritic spines, predicting heterosynaptic effects. Inhibitory synaptic inputs enhance the difference between peak calcium in stimulated spines, and peak calcium in non-stimulated spines, thereby enhancing stimulus specificity.
1 . Dorman DB, Jedrzejewska-Szmek J, Blackwell KT (2018) Inhibition enhances spatially-specific calcium encoding of synaptic input patterns in a biologically constrained model. Elife, Kennedy, Mary B, ed. [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: Basal ganglia;
Cell Type(s): Neostriatum spiny neuron;
Channel(s): Ca pump; Kir; I A; I A, slow; I CAN; I K,Ca; I Krp; I Na,t; I L high threshold; I R; I T low threshold; IK Bkca; IK Skca; Na/Ca exchanger;
Gap Junctions:
Receptor(s): AMPA; NMDA; GabaA;
Gene(s): Cav3.2 CACNA1H; Cav3.3 CACNA1I; Cav1.2 CACNA1C; Cav1.3 CACNA1D; Cav2.2 CACNA1B; Kv4.2 KCND2; Kir2.1 KCNJ2; Kv2.1 KCNB1;
Transmitter(s): Gaba; Glutamate;
Simulation Environment: GENESIS;
Model Concept(s): Calcium dynamics; Detailed Neuronal Models; Synaptic Integration; Synaptic Plasticity;
Implementer(s): Dorman, Daniel B ;
Search NeuronDB for information about:  GabaA; AMPA; NMDA; I Na,t; I L high threshold; I T low threshold; I A; I K,Ca; I CAN; I A, slow; Na/Ca exchanger; I Krp; I R; Ca pump; Kir; IK Bkca; IK Skca; Gaba; Glutamate;

/***************************		MS Model, Version 9.1	*********************
**************************** 	      Krp.g 	*********************
Rebekah Evans updated 3/22/12

function make_Krp_channel
	float Erev = -0.09
	int m_power = 2 //(Nisenbaum 1996 p 1187)
	int h_power = 1
	//table filling parameters	
    float xmin  = -0.1  
    float xmax  = 0.05  
    int  xdivsFiner = 3000
    int c = 0
    float increment =1000*{{xmax}-{xmin}}/{xdivsFiner}
    float x = -100

   str path = "Krp_channel" 
    create tabchannel {path} 
    call {path} TABCREATE X {xdivsFiner} {xmin} {xmax} 
	call {path} TABCREATE Y {xdivsFiner} {xmin} {xmax} 
//units are mV, ms
//m parameters tuned to fit Nisenbaum 1996 fig6C (minf^2) and fig 8C (mtau)
	float mA_rate = 16
	float mA_slope = 20
	float mB_rate = 2.4
	float mB_slope = -40

//h parameters tuned to fit Nisenbaum 1996 fig 9D (hinf, 87% inactivating) and 9B (htau)	
	float hA_rate = 0.01
	float hA_slope = -100
	float hB_rate = 0.4
	float hB_slope = 18
     for (c = 0; c < {xdivsFiner} + 1; c = c + 1)
		float m_alpha = {exp_form {mA_rate} {mA_slope} {-x}}   //notice x sign is reversed. see tabchanforms.g 
		float m_beta = {exp_form {mB_rate} {mB_slope} {-x}}

		float mtau= {1/(m_alpha+m_beta)}
		float m_inf= {m_alpha/(m_alpha+m_beta)}

		float h_alpha = {exp_form {hA_rate} {hA_slope} {-x}}   
		float h_beta = {exp_form {hB_rate} {hB_slope} {-x}}

		float htau= {(1/(h_alpha+h_beta))+2} //+2 is necessary to fit Nisenbaum fig 9B)
		float h_inf= ((0.87*{h_alpha/(h_alpha+h_beta)})+0.13) //(0.13 non-inact component from Nisenbaum fig 9D)

		//Nisenbaum 1996 does not specify recording temp, so room temp is assumed.
  		setfield {path} X_A->table[{c}] {{mtau}/{qfactorKrp}}
		setfield {path} X_B->table[{c}] {m_inf}
		setfield {path} Y_A->table[{c}] {{htau}/{qfactorKrp}}
		setfield {path} Y_B->table[{c}] {h_inf}
		x = x + increment
     /* Defines the powers of m and h in the Hodgkin-Huxley equation*/
   setfield {path} Ek {Erev} Xpower {m_power} Ypower {h_power} 
    tweaktau {path} X 
    tweaktau {path} Y 
//************************ End Primary Routine ********************************

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