STP

models.Synapses.STP(self, tau_rec=100.0, tau_facil=0.01, U=0.5)

Synapse exhibiting short-term facilitation and depression.

Implemented using the model of Tsodyks, Markram et al.:

Tsodyks, Uziel and Markram (2000) Synchrony Generation in Recurrent Networks with Frequency-Dependent Synapses. Journal of Neuroscience 20:RC50

Note that the time constant of the post-synaptic current is set in the neuron model, not here.

Parameters (global):

• tau_rec = 100.0 : depression time constant (ms).
• tau_facil = 0.01 : facilitation time constant (ms).
• U = 0.5 : use parameter.

Variables:

• x : recovery variable::

dx/dt = (1 - x)/tau_rec 

• u : facilitation variable::

du/dt = (U - u)/tau_facil 

Both variables are integrated event-driven.

Pre-spike events:

g_target += w * u * x
x *= (1 - u)
u += U * (1 - u)

Equivalent code:

STP = ann.Synapse(
    parameters = """
        tau_rec = 100.0 : projection
        tau_facil = 0.01 : projection
        U = 0.5
    """,
    equations = """
        dx/dt = (1 - x)/tau_rec : init = 1.0, event-driven
        du/dt = (U - u)/tau_facil : init = 0.5, event-driven
    """,
    pre_spike="""
        g_target += w * u * x
        x *= (1 - u)
        u += U * (1 - u)
    """
)