iaf_psc_exp_htum
iaf_psc_exp_htum - Leaky integrate-and-fire model with separate relative and absolute refractory period
Description
iaf_psc_exp_htum is an implementation of a leaky integrate-and-fire model with exponential-kernel postsynaptic currents (PSCs) according to [1]. The postsynaptic currents have an infinitely short rise time. In particular, this model allows setting an absolute and relative refractory time separately, as required by [1].
The threshold crossing is followed by an absolute refractory period (t_ref_abs) during which the membrane potential is clamped to the resting potential. During the total refractory period (t_ref_tot), the membrane potential evolves, but the neuron will not emit a spike, even if the membrane potential reaches threshold. The total refractory time must be larger or equal to the absolute refractory time. If equal, the refractoriness of the model if equivalent to the other models of NEST.
Note
If tau_m is very close to tau_syn_exc or tau_syn_inh, numerical problems may arise due to singularities in the propagator matrics. If this is the case, replace equal-valued parameters by a single parameter.
For details, please see IAF_neurons_singularity.ipynb
in
the NEST source code (docs/model_details
).
References
Parameters
Name |
Physical unit |
Default value |
Description |
---|---|---|---|
C_m |
pF |
250pF |
Capacitance of the membrane |
tau_m |
ms |
10ms |
Membrane time constant |
tau_syn_inh |
ms |
2ms |
Time constant of inhibitory synaptic current |
tau_syn_exc |
ms |
2ms |
Time constant of excitatory synaptic current |
t_ref_abs |
ms |
2ms |
Absolute refractory period |
t_ref_tot |
ms |
2ms |
total refractory period, if t_ref_abs == t_ref_tot iaf_psc_exp_htum equivalent to iaf_psc_exp |
E_L |
mV |
-70mV |
Resting potential |
V_reset |
mV |
-70.0mV - E_L |
Reset value of the membrane potentia. lRELATIVE TO RESTING POTENTIAL(!) I.e. the real threshold is (V_reset + E_L). |
V_th |
mV |
-55.0mV - E_L |
Threshold, RELATIVE TO RESTING POTENTIAL(!) I.e. the real threshold is (E_L + V_th) |
I_e |
pA |
0pA |
constant external input current |
State variables
Name |
Physical unit |
Default value |
Description |
---|---|---|---|
r_tot |
integer |
0 |
|
r_abs |
integer |
0 |
|
V_m |
mV |
0.0mV |
Membrane potential |
Equations
Source code
The model source code can be found in the NESTML models repository here: iaf_psc_exp_htum.