quantal_stp_synapse – Probabilistic synapse model with short term plasticity
============================================================================

Description
+++++++++++

This synapse model implements synaptic short-term depression and
short-term facilitation according to the quantal release model
described by Fuhrmann et al. [1]_ and Loebel et al. [2]_.

Each presynaptic spike will stochastically activate a fraction of
the available release sites.  This fraction is binomialy
distributed and the release probability per site is governed by the
Fuhrmann et al. (2002) model. The solution of the differential
equations is taken from Maass and Markram 2002 [3]_.

The connection weight is interpreted as the maximal weight that can
be obtained if all n release sites are activated.

.. warning::

   This synaptic plasticity rule does not take
   :ref:`precise spike timing <sim_precise_spike_times>` into
   account. When calculating the weight update, the precise spike time part
   of the timestamp is ignored.

Parameters
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The following parameters can be set in the status dictionary:

==========  ======= =========================================================
 U          real    Maximal fraction of available resources [0,1],
                    default=0.5
 u          real    Available fraction of resources [0,1], default=0.5
 p          real    Probability that a vesicle is available, default = 1.0
 n          integer Total number of release sites, default = 1
 a          integer Number of available release sites, default = n
 tau_rec    ms      Time constant for depression, default=800 ms
 tau_rec    ms      Time constant for facilitation, default=0 (off)
==========  ======= =========================================================

References
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.. [1] Fuhrmann G, Segev I, Markram H, Tsodyks MV (2002). Coding of
       temporal information by activity-dependent synapses. Journal of
       neurophysiology, 87(1):140-8.
       DOI: https://doi.org/10.1152/jn.00258.2001
.. [2] Loebel A, Silberberg G, Helbig D, Markram H, Tsodyks  MV, Richardson MJE
       (2009). Multiquantal release underlies the distribution of synaptic
       efficacies in the neocortex. Frontiers in Computational Neuroscience,
       3, 27.  DOI: https://doi.org/10.3389/neuro.10.027.2009
.. [3] Maass W, Markram H (2002). Synapses as dynamic memory buffers.
       Neural Networks, 15(2):155-161.
       DOI: https://doi.org/10.1016/S0893-6080(01)00144-7

Transmits
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SpikeEvent

See also
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:doc:`Synapse <index_synapse>`, :doc:`Short-Term Plasticity <index_short-term plasticity>`