iaf_tum_2000 – Leaky integrateandfire neuron model with exponential PSCs and integrated shortterm plasticity synapse¶
Description¶
iaf_tum_2000
is a leaky integrateandfire neuron model with shortterm synaptic
plasticity and exponential shaped postsynaptic currents (PSCs). In particular,
iaf_tum_2000
implements shortterm depression and shortterm facilitation
according to [1] by solving Eqs. (3) and (4) from that paper in an exact manner.
iaf_tum_2000
differs from iaf_psc_exp by the addition
of synaptic state variables \(x\), \(z\) and \(u\), which together
with the membrane potential \(V_\text{m}\) and synaptic current \(I_\text{syn}\)
obey the following dynamics:
where \(\Gamma_X\) is an index set over either excitatory (\(\text{X} = \text{ex}\)) or inhibitory (\(\text{X} = \text{in}\)) presynaptic neurons, \(k\) indexes the spike times of neuron \(j\), and \(d_j\) is the delay from neuron \(j\).
iaf_tum_2000
incorporates the tsodyks_synapse
computations directly in the presynaptic neuron, that is, the synaptic state
variables \(x,y,z,u\) are integrated in the presynaptic neuron instead of
the synapse model. For a presynaptic neuron with \(K\) outgoing connections
following the tsodyks_synapse
dynamics, iaf_tum_2000
saves \(K1\)
integrations of the synaptic ODEs. This makes iaf_tum_2000
very computationally
efficient in network simulations. Since the synaptic ODEs are linear, the
postsynaptic current can be found as the sum of all presynaptic synaptic
currents computed in the presynaptic neurons.
In order for synaptic depression or facilitation to take effect, both the
presynaptic and postsynaptic neuron must be of type iaf_tum_2000
.
Note
Connections between iaf_tum_2000
neurons must be through receptor_type
1.
Warning
iaf_tum_2000
does not support precise spike timing.
Using precise spike timing will result in incorrect dynamics and must therefore
be avoided.
Parameters¶
The following parameters can be set in the status dictionary.
Parameter 
Unit 
Math equivalent 
Description 


mV 
\(V_{\text{m}}\) 
Membrane potential 

mV 
\(E_\text{L}\) 
Resting membrane potential 

pF 
\(C_{\text{m}}\) 
Capacity of the membrane 

ms 
\(\tau_{\text{m}}\) 
Membrane time constant 

ms 
\(t_{\text{ref}}\) 
Duration of refractory period 

mV 
\(V_{\text{th}}\) 
Spike threshold 

mV 
\(V_{\text{reset}}\) 
Reset potential of the membrane 

ms 
\(\tau_{\text{syn, ex}}\) 
Excitatory synaptic time constant 

ms 
\(\tau_{\text{syn, in}}\) 
Inhibitory synaptic time constant 

real 
\(U\) 
Parameter determining the increase in u with each spike [0,1] 

ms 
\(\tau_{\text{fac}}\) 
Time constant for facilitation 

ms 
\(\tau_{\text{rec}}\) 
Time constant for depression 

real 
\(x\) 
Initial fraction of synaptic vesicles in the readily releasable pool [0,1] 

real 
\(y\) 
Initial fraction of synaptic vesicles in the synaptic cleft [0,1] 

real 
\(u\) 
Initial release probability of synaptic vesicles [0,1] 

pA 
\(I_\text{e}\) 
Constant input current 

mV 
\(V_{\text{min}}\) 
Absolute lower value for the membrane potenial (default \(\infty\)) 
References¶
Transmits¶
SpikeEvent
See also¶
Neuron, IntegrateAndFire, CurrentBased, Synapse, ShortTerm Plasticity