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class_WeightUpdateModels_PiecewiseSTDP.rst

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.. index:: pair: class; WeightUpdateModels::PiecewiseSTDP

class WeightUpdateModels::PiecewiseSTDP

.. toctree::
        :hidden:

Overview

This is a simple STDP rule including a time delay for the finite transmission speed of the synapse. :ref:`More...<details-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP>`

.. ref-code-block:: cpp
        :class: doxyrest-overview-code-block

        #include <weightUpdateModels.h>

        class PiecewiseSTDP: public :ref:`WeightUpdateModels::Base<doxid-d2/d05/classWeightUpdateModels_1_1Base>`
        {
        public:
                // methods

                :target:`DECLARE_WEIGHT_UPDATE_MODEL<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1a9ef28608d86ff2be8e68e9a97134ce05>`(
                        PiecewiseSTDP,
                        10,
                        2,
                        0,
                        0
                        );

                virtual :ref:`StringVec<doxid-db/d97/classSnippet_1_1Base_1a06cd0f6da1424a20163e12b6fec62519>` :ref:`getParamNames<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1a3401601af479387c1dcbc4d986741c81>`() const;
                virtual :ref:`VarVec<doxid-d6/d97/classModels_1_1Base_1a5a6bc95969a38ac1ac68ab4a0ba94c75>` :ref:`getVars<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1aef7011a4e9e3975ee432e2f901ccf4a9>`() const;
                virtual std::string :ref:`getSimCode<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1aaf6969f0f388155f2efedca6015c0b70>`() const;
                virtual std::string :ref:`getLearnPostCode<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1a8e054d3dd776a3b8d07af81c5d7d8647>`() const;
                virtual :ref:`DerivedParamVec<doxid-db/d97/classSnippet_1_1Base_1ad14217cebf11eddffa751a4d5c4792cb>` :ref:`getDerivedParams<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1a9e85e5c8178425856929c747d53c421f>`() const;
                virtual bool :ref:`isPreSpikeTimeRequired<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1a060eb8fe3f26e106c662519d23a93717>`() const;
                virtual bool :ref:`isPostSpikeTimeRequired<doxid-df/d86/classWeightUpdateModels_1_1PiecewiseSTDP_1a03875502d4f8594bfd1f53d248ae63c2>`() const;
        };

Inherited Members

.. ref-code-block:: cpp
        :class: doxyrest-overview-inherited-code-block

        public:
                // typedefs

                typedef std::vector<std::string> :ref:`StringVec<doxid-db/d97/classSnippet_1_1Base_1a06cd0f6da1424a20163e12b6fec62519>`;
                typedef std::vector<:ref:`EGP<doxid-dd/d5d/structSnippet_1_1Base_1_1EGP>`> :ref:`EGPVec<doxid-db/d97/classSnippet_1_1Base_1a43ece29884e2c6cabffe9abf985807c6>`;
                typedef std::vector<:ref:`ParamVal<doxid-d7/dda/structSnippet_1_1Base_1_1ParamVal>`> :ref:`ParamValVec<doxid-db/d97/classSnippet_1_1Base_1a0156727ddf8f9c9cbcbc0d3d913b6b48>`;
                typedef std::vector<:ref:`DerivedParam<doxid-d9/d0c/structSnippet_1_1Base_1_1DerivedParam>`> :ref:`DerivedParamVec<doxid-db/d97/classSnippet_1_1Base_1ad14217cebf11eddffa751a4d5c4792cb>`;
                typedef std::vector<:ref:`Var<doxid-d5/d42/structModels_1_1Base_1_1Var>`> :ref:`VarVec<doxid-d6/d97/classModels_1_1Base_1a5a6bc95969a38ac1ac68ab4a0ba94c75>`;

                // structs

                struct :ref:`DerivedParam<doxid-d9/d0c/structSnippet_1_1Base_1_1DerivedParam>`;
                struct :ref:`EGP<doxid-dd/d5d/structSnippet_1_1Base_1_1EGP>`;
                struct :ref:`ParamVal<doxid-d7/dda/structSnippet_1_1Base_1_1ParamVal>`;
                struct :ref:`Var<doxid-d5/d42/structModels_1_1Base_1_1Var>`;

                // methods

                virtual :ref:`~Base<doxid-db/d97/classSnippet_1_1Base_1a17a9ca158277401f2c190afb1e791d1f>`();
                virtual :ref:`StringVec<doxid-db/d97/classSnippet_1_1Base_1a06cd0f6da1424a20163e12b6fec62519>` :ref:`getParamNames<doxid-db/d97/classSnippet_1_1Base_1a0c8374854fbdc457bf0f75e458748580>`() const;
                virtual :ref:`DerivedParamVec<doxid-db/d97/classSnippet_1_1Base_1ad14217cebf11eddffa751a4d5c4792cb>` :ref:`getDerivedParams<doxid-db/d97/classSnippet_1_1Base_1ab01de002618efa59541c927ffdd463f5>`() const;
                virtual :ref:`VarVec<doxid-d6/d97/classModels_1_1Base_1a5a6bc95969a38ac1ac68ab4a0ba94c75>` :ref:`getVars<doxid-d6/d97/classModels_1_1Base_1a9df8ba9bf6d971a574ed4745f6cf946c>`() const;
                virtual :ref:`EGPVec<doxid-db/d97/classSnippet_1_1Base_1a43ece29884e2c6cabffe9abf985807c6>` :ref:`getExtraGlobalParams<doxid-d6/d97/classModels_1_1Base_1a7fdddb7d19382736b330ade62c441de1>`() const;
                size_t :ref:`getVarIndex<doxid-d6/d97/classModels_1_1Base_1afa0e39df5002efc76448e180f82825e4>`(const std::string& varName) const;
                size_t :ref:`getExtraGlobalParamIndex<doxid-d6/d97/classModels_1_1Base_1ae046c19ad56dfb2808c5f4d2cc7475fe>`(const std::string& paramName) const;
                virtual std::string :ref:`getSimCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1aff2152fb55b5b0148491ca4eed9291eb>`() const;
                virtual std::string :ref:`getEventCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a090f5529defe517fabf84c543209406f>`() const;
                virtual std::string :ref:`getLearnPostCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1abd6d3ec97fb1da0f5750f71c7afc09b1>`() const;
                virtual std::string :ref:`getSynapseDynamicsCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a307cb4e18479682b74972257c5d28dc5>`() const;
                virtual std::string :ref:`getEventThresholdConditionCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a3157e0e66cdc654be4ef4ad67024f84d>`() const;
                virtual std::string :ref:`getSimSupportCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a948b94c553782e9cc05a59bda014fe26>`() const;
                virtual std::string :ref:`getLearnPostSupportCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1af98ae8f3d545f8d66d0f80662bf5b322>`() const;
                virtual std::string :ref:`getSynapseDynamicsSuppportCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a7aae3190642d0bbe7f3f6fa01021783f>`() const;
                virtual std::string :ref:`getPreSpikeCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a79e16d6c154e21a8ca7e56599cbe553b>`() const;
                virtual std::string :ref:`getPostSpikeCode<doxid-d2/d05/classWeightUpdateModels_1_1Base_1abb81b1a933f13ba2af62c088387e186f>`() const;
                virtual :ref:`VarVec<doxid-d6/d97/classModels_1_1Base_1a5a6bc95969a38ac1ac68ab4a0ba94c75>` :ref:`getPreVars<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a949a9adcbc40d4ae9bbb51b2ec08dff5>`() const;
                virtual :ref:`VarVec<doxid-d6/d97/classModels_1_1Base_1a5a6bc95969a38ac1ac68ab4a0ba94c75>` :ref:`getPostVars<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a97a0a4fb30a66bb629cd88306e659105>`() const;
                virtual bool :ref:`isPreSpikeTimeRequired<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a86fb753d87f35b53d789f96c6189a911>`() const;
                virtual bool :ref:`isPostSpikeTimeRequired<doxid-d2/d05/classWeightUpdateModels_1_1Base_1ad93200ea885e60a88c108db10349edea>`() const;
                size_t :ref:`getPreVarIndex<doxid-d2/d05/classWeightUpdateModels_1_1Base_1ac8b3e37eeb3f0034ebba50ec01c2840e>`(const std::string& varName) const;
                size_t :ref:`getPostVarIndex<doxid-d2/d05/classWeightUpdateModels_1_1Base_1a5812718ff39cc394f1c6242e3d3f0987>`(const std::string& varName) const;

Detailed Documentation

This is a simple STDP rule including a time delay for the finite transmission speed of the synapse.

The STDP window is defined as a piecewise function:

LEARN1SYNAPSE_explain_html.png

width=10cm

The STDP curve is applied to the raw synaptic conductance gRaw, which is then filtered through the sugmoidal filter displayed above to obtain the value of g.

The STDP curve implies that unpaired pre- and post-synaptic spikes incur a negative increment in gRaw (and hence in g).

The time of the last spike in each neuron, "sTXX", where XX is the name of a neuron population is (somewhat arbitrarily) initialised to -10.0 ms. If neurons never spike, these spike times are used.

It is the raw synaptic conductance gRaw that is subject to the STDP rule. The resulting synaptic conductance is a sigmoid filter of gRaw. This implies that g is initialised but not gRaw, the synapse will revert to the value that corresponds to gRaw.

An example how to use this synapse correctly is given in map_classol.cc (MBody1 userproject):

.. ref-code-block:: cpp

        for (int i= 0; i < model.neuronN[1]*model.neuronN[3]; i++) {
                if (gKCDN[i] < 2.0*SCALAR_MIN){
                    cnt++;
                    fprintf(stdout, "Too low conductance value %e detected and set to 2*SCALAR_MIN= %e, at index %d \n", gKCDN[i], 2*SCALAR_MIN, i);
                    gKCDN[i] = 2.0*SCALAR_MIN; //to avoid log(0)/0 below
                }
                scalar tmp = gKCDN[i] / myKCDN_p[5]*2.0 ;
                gRawKCDN[i]=  0.5 * log( tmp / (2.0 - tmp)) /myKCDN_p[7] + myKCDN_p[6];
        }
        cerr << "Total number of low value corrections: " << cnt << endl;

One cannot set values of g fully to 0, as this leads to gRaw = -infinity and this is not support. I.e., 'g' needs to be some nominal value > 0 (but can be extremely small so that it acts like it's 0).

The model has 2 variables:

  • g: conductance of scalar type
  • gRaw: raw conductance of scalar type

Parameters are (compare to the figure above):

  • tLrn: Time scale of learning changes
  • tChng: Width of learning window
  • tDecay: Time scale of synaptic strength decay
  • tPunish10: Time window of suppression in response to 1/0
  • tPunish01: Time window of suppression in response to 0/1
  • gMax: Maximal conductance achievable
  • gMid: Midpoint of sigmoid g filter curve
  • gSlope: Slope of sigmoid g filter curve
  • tauShift: Shift of learning curve
  • gSyn0: Value of syn conductance g decays to

Methods

.. index:: pair: function; getParamNames

.. ref-code-block:: cpp
        :class: doxyrest-title-code-block

        virtual :ref:`StringVec<doxid-db/d97/classSnippet_1_1Base_1a06cd0f6da1424a20163e12b6fec62519>` getParamNames() const

Gets names of of (independent) model parameters.

.. index:: pair: function; getVars

.. ref-code-block:: cpp
        :class: doxyrest-title-code-block

        virtual :ref:`VarVec<doxid-d6/d97/classModels_1_1Base_1a5a6bc95969a38ac1ac68ab4a0ba94c75>` getVars() const

Gets names and types (as strings) of model variables.

.. index:: pair: function; getSimCode

.. ref-code-block:: cpp
        :class: doxyrest-title-code-block

        virtual std::string getSimCode() const

Gets simulation code run when 'true' spikes are received.

.. index:: pair: function; getLearnPostCode

.. ref-code-block:: cpp
        :class: doxyrest-title-code-block

        virtual std::string getLearnPostCode() const

Gets code to include in the learnSynapsesPost kernel/function.

For examples when modelling STDP, this is where the effect of postsynaptic spikes which occur after presynaptic spikes are applied.

.. index:: pair: function; getDerivedParams

.. ref-code-block:: cpp
        :class: doxyrest-title-code-block

        virtual :ref:`DerivedParamVec<doxid-db/d97/classSnippet_1_1Base_1ad14217cebf11eddffa751a4d5c4792cb>` getDerivedParams() const

Gets names of derived model parameters and the function objects to call to Calculate their value from a vector of model parameter values

.. index:: pair: function; isPreSpikeTimeRequired

.. ref-code-block:: cpp
        :class: doxyrest-title-code-block

        virtual bool isPreSpikeTimeRequired() const

Whether presynaptic spike times are needed or not.

.. index:: pair: function; isPostSpikeTimeRequired

.. ref-code-block:: cpp
        :class: doxyrest-title-code-block

        virtual bool isPostSpikeTimeRequired() const

Whether postsynaptic spike times are needed or not.