iaf_chxk_2008

iaf_chxk_2008 - Conductance based leaky integrate-and-fire neuron model used in Casti et al. 2008

Description

iaf_chxk_2008 is an implementation of a spiking neuron using IAF dynamics with conductance-based synapses [1]. A spike is emitted when the membrane potential is crossed from below. After a spike, an afterhyperpolarizing (AHP) conductance is activated which repolarizes the neuron over time. Membrane potential is not reset explicitly and the model also has no explicit refractory time.

The AHP conductance and excitatory and inhibitory synaptic input conductances follow alpha-function time courses as in the iaf_cond_alpha model.

Note

In the original Fortran implementation underlying [1], all previous AHP activation was discarded when a new spike occurred, leading to reduced AHP currents in particular during periods of high spiking activity. Set ahp_bug to true to obtain this behavior in the model.

References

[1] (1,2)

Casti A, Hayot F, Xiao Y, Kaplan E (2008) A simple model of retina-LGN transmission. Journal of Computational Neuroscience 24:235-252. DOI: https://doi.org/10.1007/s10827-007-0053-7

See also

iaf_cond_alpha

Parameters

Name	Physical unit	Default value	Description
V_th	mV	-45.0mV	Threshold potential
E_exc	mV	20mV	Excitatory reversal potential
E_inh	mV	-90mV	Inhibitory reversal potential
g_L	nS	100nS	Leak conductance
C_m	pF	1000.0pF	Membrane capacitance
E_L	mV	-60.0mV	Leak reversal Potential (aka resting potential)
tau_syn_exc	ms	1ms	Synaptic time constant of excitatory synapse
tau_syn_inh	ms	1ms	Synaptic time constant of inhibitory synapse
tau_ahp	ms	0.5ms	Afterhyperpolarization (AHP) time constant
G_ahp	nS	443.8nS	AHP conductance
E_ahp	mV	-95mV	AHP potential
ahp_bug	boolean	false	If true, discard AHP conductance value from previous spikes
I_e	pA	0pA	constant external input current

State variables

Name	Physical unit	Default value	Description
V_m	mV	E_L	membrane potential
V_m_prev	mV	E_L	membrane potential
g_ahp	nS	0nS	AHP conductance
g_ahp	nS / ms	0nS / ms	AHP conductance

Equations

\[\frac{ d^2 g_{ahp} } { dt^2 }= \frac{ -2 \cdot g_{ahp}' } { \tau_{ahp} } - \frac{ g_{ahp} } { { \tau_{ahp} }^{ 2 } }\]

\[\frac{ dV_{m} } { dt }= \frac 1 { C_{m} } \left( { (-I_{leak} - I_{syn,exc} - I_{syn,inh} - I_{ahp} + I_{e} + I_{stim}) } \right)\]

Source code

The model source code can be found in the NESTML models repository here: iaf_chxk_2008.

Characterisation