Survey of electrically evoked responses in the retina (Tsai et al 2017)

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Accession:262389
"Cones and horizontal cells are interconnected to adjacent cones and horizontal cells, respectively, with gap junctions. In particular, the horizontal cell gap junctional conductance is modulated by exogenous factors. What roles does this conductance play in the electrically evoked responses of horizontal cells? To address this question, we constructed a computational model consisting of the cone and horizontal cell layer..."
Reference:
1 . Tsai D, Morley JW, Suaning GJ, Lovell NH (2017) Survey of electrically evoked responses in the retina - stimulus preferences and oscillation among neurons. Sci Rep 7:13802 [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type: Synapse; Extracellular;
Brain Region(s)/Organism: Retina;
Cell Type(s): Retina photoreceptor cone GLU cell; Retina horizontal cell;
Channel(s):
Gap Junctions: Gap junctions;
Receptor(s):
Gene(s):
Transmitter(s):
Simulation Environment: NEURON;
Model Concept(s): Activity Patterns; Oscillations;
Implementer(s): Tsai, David [d.tsai at unsw.edu.au];
Search NeuronDB for information about:  Retina photoreceptor cone GLU cell;
TITLE ICa for horizontal cell
: Calcium current (ICa) for horizontal cells
: 
: Based on parameters of Aoyama et al. (2000)


INDEPENDENT {t FROM 0 TO 1 WITH 1 (ms)}

NEURON {
	SUFFIX HzICa
	USEION ca WRITE ica
	RANGE gbar
	RANGE m_inf
	RANGE tau_m
	RANGE m_exp
}

UNITS {
	(mA) = (milliamp)
	(mV) = (millivolt)
}

PARAMETER {
    gbar = 8.4906e-05 (mho/cm2) : 9 ns total
    eca  = 53.040  (mV)         : 2 mM outside, 30 uM inside
}

STATE {
    m
}

ASSIGNED {
    v       (mV)
	ica     (mA/cm2)
    celsius (degC)
    dt      (ms)

    m_inf
	tau_m
	m_exp
	tadj
}

BREAKPOINT {
	SOLVE states
	ica = gbar * m*m*m*m * (v - eca)
}

PROCEDURE states() {
    : exact when v held constant
	evaluate_fct(v)
	m = m + m_exp * (m_inf - m)
}

UNITSOFF

INITIAL {
	m = 0.059
    tadj = 3.0 ^ ((celsius-25)/10)  : correction for physio temp
}

PROCEDURE evaluate_fct(v(mV)) { LOCAL a, b, v2
    a = (240 * (68-v)) / ( exp( (68-v)/21 ) - 1)
    b = 800 / ( exp( (55+v)/55 ) + 1 )
    tau_m = 1 / (a + b) / tadj
	m_inf = a / (a + b)

	m_exp = 1 - exp(-dt/tau_m)
}

UNITSON


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