stdp_pl_synapse_hom.h

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/*
 *  stdp_pl_synapse_hom.h
 *
 *  This file is part of NEST.
 *
 *  Copyright (C) 2004 The NEST Initiative
 *
 *  NEST is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  NEST is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with NEST.  If not, see <http://www.gnu.org/licenses/>.
 *
 */
 
#ifndef STDP_PL_SYNAPSE_HOM_H
#define STDP_PL_SYNAPSE_HOM_H
 
// C++ includes:
#include <cmath>
 
// Includes from nestkernel:
#include "connection.h"
 
namespace nest
{
 
/* BeginUserDocs: synapse, chemical, functional, stdp
 
Short description
+++++++++++++++++
 
Synapse type for spike-timing dependent plasticity with power law
 
Description
+++++++++++
 
``stdp_pl_synapse`` is a connector to create synapses with spike time
dependent plasticity using homoegeneous parameters (as defined in :footcite:p:`Morrison2007c`).
 
Parameters
++++++++++
 
=========  ======  ====================================================
 tau_plus  ms      Time constant of STDP window, potentiation
                   (tau_minus defined in postsynaptic neuron)
 lambda    real    Learning rate
 alpha     real    Asymmetry parameter (scales depressing increments as
                   alpha*lambda)
 mu        real    Weight dependence exponent, potentiation
=========  ======  ====================================================
 
The parameters can only be set by SetDefaults and apply to all synapses of
the model.
 
.. 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.
 
References
++++++++++
 
.. footbibliography::
 
Transmits
+++++++++
 
SpikeEvent
 
See also
++++++++
 
stdp_synapse, tsodyks_synapse, static_synapse
 
Examples using this model
+++++++++++++++++++++++++
 
.. listexamples:: stdp_pl_synapse_hom
 
EndUserDocs */
 
class STDPPLHomCommonProperties : public CommonSynapseProperties
{
 
public:
  STDPPLHomCommonProperties();
 
  void get_status( Dictionary& d ) const;
 
  void set_status( const Dictionary& d, ConnectorModel& cm );
 
  // data members common to all connections
  double tau_plus_;
  double tau_plus_inv_;  
  double lambda_;
  double alpha_;
  double mu_;
};
 
 
void register_stdp_pl_synapse_hom( const std::string& name );
 
template < typename targetidentifierT >
class stdp_pl_synapse_hom : public Connection< targetidentifierT >
{
 
public:
  typedef STDPPLHomCommonProperties CommonPropertiesType;
  typedef Connection< targetidentifierT > ConnectionBase;
 
  static constexpr ConnectionModelProperties properties = ConnectionModelProperties::HAS_DELAY
    | ConnectionModelProperties::IS_PRIMARY | ConnectionModelProperties::SUPPORTS_HPC
    | ConnectionModelProperties::SUPPORTS_LBL;
 
  stdp_pl_synapse_hom();
 
  stdp_pl_synapse_hom( const stdp_pl_synapse_hom& ) = default;
  stdp_pl_synapse_hom& operator=( const stdp_pl_synapse_hom& ) = default;
 
  // Explicitly declare all methods inherited from the dependent base
  // ConnectionBase. This avoids explicit name prefixes in all places these
  // functions are used. Since ConnectionBase depends on the template parameter,
  // they are not automatically found in the base class.
  using ConnectionBase::get_delay;
  using ConnectionBase::get_delay_steps;
  using ConnectionBase::get_rport;
  using ConnectionBase::get_target;
 
  void get_status( Dictionary& d ) const;
 
  void set_status( const Dictionary& d, ConnectorModel& cm );
 
  bool send( Event& e, size_t t, const STDPPLHomCommonProperties& );
 
  class ConnTestDummyNode : public ConnTestDummyNodeBase
  {
  public:
    // Ensure proper overriding of overloaded virtual functions.
    // Return values from functions are ignored.
    using ConnTestDummyNodeBase::handles_test_event;
    size_t
    handles_test_event( SpikeEvent&, size_t ) override
    {
      return invalid_port;
    }
  };
 
  /*
   * This function calls check_connection on the sender and checks if the
   * receiver accepts the event type and receptor type requested by the sender.
   * Node::check_connection() will either confirm the receiver port by returning
   * true or false if the connection should be ignored.
   * We have to override the base class' implementation, since for STDP
   * connections we have to call register_stdp_pl_connection on the target
   * neuron to inform the Archiver to collect spikes for this connection.
   *
   * \param s The source node
   * \param r The target node
   * \param receptor_type The ID of the requested receptor type
   */
  void
  check_connection( Node& s, Node& t, size_t receptor_type, const CommonPropertiesType& )
  {
    ConnTestDummyNode dummy_target;
 
    ConnectionBase::check_connection_( dummy_target, s, t, receptor_type );
 
    t.register_stdp_connection( t_lastspike_ - get_delay(), get_delay() );
  }
 
  void
  set_weight( double w )
  {
    weight_ = w;
  }
 
private:
  double
  facilitate_( double w, double kplus, const STDPPLHomCommonProperties& cp )
  {
    return w + ( cp.lambda_ * std::pow( w, cp.mu_ ) * kplus );
  }
 
  double
  depress_( double w, double kminus, const STDPPLHomCommonProperties& cp )
  {
    double new_w = w - ( cp.lambda_ * cp.alpha_ * w * kminus );
    return new_w > 0.0 ? new_w : 0.0;
  }
 
  // data members of each connection
  double weight_;
  double Kplus_;
  double t_lastspike_;
};
 
template < typename targetidentifierT >
constexpr ConnectionModelProperties stdp_pl_synapse_hom< targetidentifierT >::properties;
 
//
// Implementation of class stdp_pl_synapse_hom.
//
 
template < typename targetidentifierT >
inline bool
stdp_pl_synapse_hom< targetidentifierT >::send( Event& e, size_t t, const STDPPLHomCommonProperties& cp )
{
  // synapse STDP depressing/facilitation dynamics
 
  const double t_spike = e.get_stamp().get_ms();
 
  // t_lastspike_ = 0 initially
 
  Node* target = get_target( t );
 
  double dendritic_delay = get_delay();
 
  // get spike history in relevant range (t1, t2] from postsynaptic neuron
  std::deque< histentry >::iterator start;
  std::deque< histentry >::iterator finish;
  target->get_history( t_lastspike_ - dendritic_delay, t_spike - dendritic_delay, &start, &finish );
 
  // facilitation due to postsynaptic spikes since last pre-synaptic spike
  double minus_dt;
  while ( start != finish )
  {
    minus_dt = t_lastspike_ - ( start->t_ + dendritic_delay );
    start++;
    // get_history() should make sure that
    // start->t_ > t_lastspike - dendritic_delay, i.e. minus_dt < 0
    assert( minus_dt < -1.0 * kernel().connection_manager.get_stdp_eps() );
    weight_ = facilitate_( weight_, Kplus_ * std::exp( minus_dt * cp.tau_plus_inv_ ), cp );
  }
 
  // depression due to new pre-synaptic spike
  weight_ = depress_( weight_, target->get_K_value( t_spike - dendritic_delay ), cp );
 
  e.set_receiver( *target );
  e.set_weight( weight_ );
  e.set_delay_steps( get_delay_steps() );
  e.set_rport( get_rport() );
  e();
 
  Kplus_ = Kplus_ * std::exp( ( t_lastspike_ - t_spike ) * cp.tau_plus_inv_ ) + 1.0;
 
  t_lastspike_ = t_spike;
 
  return true;
}
 
template < typename targetidentifierT >
stdp_pl_synapse_hom< targetidentifierT >::stdp_pl_synapse_hom()
  : ConnectionBase()
  , weight_( 1.0 )
  , Kplus_( 0.0 )
  , t_lastspike_( 0.0 )
{
}
 
template < typename targetidentifierT >
void
stdp_pl_synapse_hom< targetidentifierT >::get_status( Dictionary& d ) const
{
 
  // base class properties, different for individual synapse
  ConnectionBase::get_status( d );
  d[ names::weight ] = weight_;
 
  // own properties, different for individual synapse
  d[ names::Kplus ] = Kplus_;
  d[ names::size_of ] = static_cast< long >( sizeof( *this ) );
}
 
template < typename targetidentifierT >
void
stdp_pl_synapse_hom< targetidentifierT >::set_status( const Dictionary& d, ConnectorModel& cm )
{
  // base class properties
  ConnectionBase::set_status( d, cm );
  d.update_value( names::weight, weight_ );
 
  d.update_value( names::Kplus, Kplus_ );
}
 
}  // of namespace nest
 
#endif  // of #ifndef STDP_PL_SYNAPSE_HOM_H