stdp_facetshw_synapse_hom - Synapse type for spike-timing dependent
plasticity using homogeneous parameters,
i.e. all synapses have the same parameters.
stdp_facetshw_synapse is a connector to create synapses with spike-timing
dependent plasticity (as defined in [1]).
This connector is a modified version of stdp_synapse.
It includes constraints of the hardware developed in the FACETS (BrainScaleS)
project [2,3], as e.g. 4-bit weight resolution, sequential updates of groups
of synapses and reduced symmetric nearest-neighbor spike pairing scheme. For
details see [3].
The modified spike pairing scheme requires the calculation of tau_minus_
within this synapse and not at the neuron site via Kplus_ like in
stdp_connection_hom.
\verbatim embed:rst
======================= =========== ===========================================
**Common properties**
-------------------------------------------------------------------------------
tau_plus ms Time constant of STDP window, causal branch
tau_minus_stdp ms Time constant of STDP window, anti-causal
branch
Wmax real Maximum allowed weight
no_synapses integer Total number of synapses
synapses_per_driver integer Number of synapses updated at once
driver_readout_time real Time for processing of one synapse row
(synapse line driver)
readout_cycle_duration real Duration between two subsequent
updates of same synapse (synapse line
driver)
lookuptable_0 list of Three look-up tables (LUT)
integers
lookuptable_1 list of
integers
lookuptable_2 list of
integers
configbit_0 list of Configuration bits for evaluation
integers function. For details see code in
function eval_function_ and [4]
(configbit[0]=e_cc, ..[1]=e_ca,
..[2]=e_ac, ..[3]=e_aa).
Depending on these two sets of
configuration bits weights are updated
according LUTs (out of three: (1,0),
(0,1), (1,1)). For (0,0) continue
without reset.
configbit_1 list of
integers
reset_pattern list of Configuration bits for reset behavior.
integers Two bits for each LUT (reset causal
and acausal). In hardware only (all
false; never reset) or (all true;
always reset) is allowed.
======================= =========== ===========================================
============ ======= =====================================================
**Individual properties**
---------------------------------------------------------------------------
a_causal real Causal and anti-causal spike pair accumulations
a_acausal real
a_thresh_th real Two thresholds used in evaluation function
No common property, because variation of analog
synapse circuitry can be applied here
a_thresh_tl real
synapse_id integer Synapse ID, used to assign synapses to groups (synapse
drivers)
============ ======= =====================================================
\endverbatim
SpikeEvent
The synapse IDs are assigned to each synapse in an ascending order (0,1,2,
...) according their first presynaptic activity and is used to group synapses
that are updated at once. It is possible to avoid activity dependent synapse
ID assignments by manually setting the no_synapses and the synapse_id(s)
before running the simulation. The weights will be discretized after the
first presynaptic activity at a synapse.
Common properties can only be set on the synapse model using SetDefaults.
\verbatim embed:rst
.. [1] Morrison A, Diesmann M, Gerstner W (2008). Phenomenological models of
synaptic plasticity based on spike-timing. Biological Cybernetics,
98:459-478. DOI: https://doi.org/10.1007/s00422-008-0233-1
.. [2] Schemmel J, Gruebl A, Meier K, Mueller E (2006). Implementing synaptic
plasticity in a VLSI spiking neural network model. In Proceedings of the
2006 International Joint Conference on Neural Networks, pp.1--6,
IEEE Press. DOI: https://doi.org/10.1109/IJCNN.2006.246651
.. [3] Pfeil T, Potjans TC, Schrader S, Potjans W, Schemmel J, Diesmann M,
Meier K (2012). Is a 4-bit synaptic weight resolution enough? -
constraints on enabling spike-timing dependent plasticity in
neuromorphic hardware. Frontiers in Neuroscience 6(90).
DOI: https://doi.org/10.3389/fnins.2012.00090
.. [4] Friedmann, S. in preparation
\endverbatim
Thomas Pfeil (TP), Moritz Helias, Abigail Morrison
July 2011
/var/www/debian/nest/nest-simulator-2.18.0/models/stdp_connection_facetshw_hom.h