iaf_psc_delta.h

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/*
 *  iaf_psc_delta.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 IAF_PSC_DELTA_H
#define IAF_PSC_DELTA_H

#include "nest.h"
#include "event.h"
#include "archiving_node.h"
#include "ring_buffer.h"
#include "connection.h"
#include "universal_data_logger.h"

namespace nest{
  
  class Network;

  /* BeginDocumentation
     Name: iaf_psc_delta - Leaky integrate-and-fire neuron model.

     Description:

     iaf_psc_delta is an implementation of a leaky integrate-and-fire model
     where the potential jumps on each spike arrival. 

     The threshold crossing is followed by an absolute refractory period
     during which the membrane potential is clamped to the resting potential.

     Spikes arriving while the neuron is refractory, are discarded by
     default. If the property "refractory_input" is set to true, such
     spikes are added to the membrane potential at the end of the
     refractory period, dampened according to the interval between
     arrival and end of refractoriness.

     The linear subthresold dynamics is integrated by the Exact
     Integration scheme [1]. The neuron dynamics is solved on the time
     grid given by the computation step size. Incoming as well as emitted
     spikes are forced to that grid.  

     An additional state variable and the corresponding differential
     equation represents a piecewise constant external current.

     The general framework for the consistent formulation of systems with
     neuron like dynamics interacting by point events is described in
     [1].  A flow chart can be found in [2].

     Critical tests for the formulation of the neuron model are the
     comparisons of simulation results for different computation step
     sizes. sli/testsuite/nest contains a number of such tests.
  
     The iaf_psc_delta is the standard model used to check the consistency
     of the nest simulation kernel because it is at the same time complex
     enough to exhibit non-trivial dynamics and simple enough compute
     relevant measures analytically.

     Remarks:

     The present implementation uses individual variables for the
     components of the state vector and the non-zero matrix elements of
     the propagator.  Because the propagator is a lower triangular matrix
     no full matrix multiplication needs to be carried out and the
     computation can be done "in place" i.e. no temporary state vector
     object is required.

     The template support of recent C++ compilers enables a more succinct
     formulation without loss of runtime performance already at minimal
     optimization levels. A future version of iaf_psc_delta will probably
     address the problem of efficient usage of appropriate vector and
     matrix objects.


     Parameters: 

     The following parameters can be set in the status dictionary.

     V_m        double - Membrane potential in mV 
     E_L        double - Resting membrane potential in mV. 
     C_m        double - Specific capacitance of the membrane in pF/mum^2 
     tau_m      double - Membrane time constant in ms. 
     t_ref      double - Duration of refractory period in ms. 
     V_th       double - Spike threshold in mV. 
     V_reset    double - Reset potential of the membrane in mV.
     I_e        double - Constant input current in pA. 
     V_min      double - Absolute lower value for the membrane potential.

     refractory_input bool - If true, do not discard input during
     refractory period. Default: false.
 
     References:
     [1] Rotter S & Diesmann M (1999) Exact digital simulation of time-invariant
     linear systems with applications to neuronal modeling. Biologial Cybernetics
     81:381-402.
     [2] Diesmann M, Gewaltig M-O, Rotter S, & Aertsen A (2001) State space 
     analysis of synchronous spiking in cortical neural networks. 
     Neurocomputing 38-40:565-571.

     Sends: SpikeEvent

     Receives: SpikeEvent, CurrentEvent, DataLoggingRequest

     Author:  September 1999, Diesmann, Gewaltig
     SeeAlso: iaf_psc_alpha, iaf_psc_exp, iaf_neuron, iaf_psc_delta_canon
  */

  class iaf_psc_delta:
  public Archiving_Node
  {
    
  public:        
    
    iaf_psc_delta();
    iaf_psc_delta(const iaf_psc_delta&);

    using Node::handle;
    using Node::handles_test_event;

    port send_test_event(Node &, rport, synindex, bool);

    void handle(SpikeEvent &);
    void handle(CurrentEvent &);
    void handle(DataLoggingRequest &);
    
    port handles_test_event(SpikeEvent&, rport);
    port handles_test_event(CurrentEvent&, rport);
    port handles_test_event(DataLoggingRequest &, rport);

    void get_status(DictionaryDatum &) const;
    void set_status(const DictionaryDatum &);

  private:

    void init_state_(const Node& proto);
    void init_buffers_();
    void calibrate();

    void update(Time const &, const long_t, const long_t);

    // The next two classes need to be friends to access the State_ class/member
    friend class RecordablesMap<iaf_psc_delta>;
    friend class UniversalDataLogger<iaf_psc_delta>;
    
    // ---------------------------------------------------------------- 

    struct Parameters_ {
      double_t tau_m_;

      double_t c_m_;
    
      double_t t_ref_;

      double_t E_L_;

      double_t I_e_;

      double_t V_th_;

      double_t V_min_;

      double_t V_reset_;

      bool     with_refr_input_;   

      Parameters_();  

      void get(DictionaryDatum&) const;  

       double set(const DictionaryDatum&);
    };
    
    // ---------------------------------------------------------------- 

    struct State_ {
      double_t     y0_;
      double_t     y3_; 

      int_t    r_;  

      double_t    refr_spikes_buffer_;

      State_();  
      
      void get(DictionaryDatum&, const Parameters_&) const;

      void set(const DictionaryDatum&, const Parameters_&, double);
    };    

    // ---------------------------------------------------------------- 

    struct Buffers_ {
      Buffers_(iaf_psc_delta &);
      Buffers_(const Buffers_ &, iaf_psc_delta &);

      RingBuffer spikes_;
      RingBuffer currents_;  

      UniversalDataLogger<iaf_psc_delta> logger_;
    };
    
    // ---------------------------------------------------------------- 

    struct Variables_ { 
    
      double_t P30_;
      double_t P33_;  

      int_t       RefractoryCounts_;

    };

    // Access functions for UniversalDataLogger -------------------------------

    double_t get_V_m_() const { return S_.y3_ + P_.E_L_; }

    // ---------------------------------------------------------------- 

    Parameters_ P_;
    State_      S_;
    Variables_  V_;
    Buffers_    B_;
    static RecordablesMap<iaf_psc_delta> recordablesMap_;
  };

  
inline
port nest::iaf_psc_delta::send_test_event(Node& target, rport receptor_type, synindex, bool)
{
  SpikeEvent e;
  e.set_sender(*this);
  return target.handles_test_event(e, receptor_type);
}
  
inline
port iaf_psc_delta::handles_test_event(SpikeEvent&, rport receptor_type)
{
  if (receptor_type != 0)
    throw UnknownReceptorType(receptor_type, get_name());
  return 0;
}
 
inline
port iaf_psc_delta::handles_test_event(CurrentEvent&, rport receptor_type)
{
  if (receptor_type != 0)
    throw UnknownReceptorType(receptor_type, get_name());
  return 0;
}
 
inline
port iaf_psc_delta::handles_test_event(DataLoggingRequest& dlr, 
                       rport receptor_type)
{
  if (receptor_type != 0)
    throw UnknownReceptorType(receptor_type, get_name());
  return B_.logger_.connect_logging_device(dlr, recordablesMap_);
}

inline
void iaf_psc_delta::get_status(DictionaryDatum &d) const
{
  P_.get(d);
  S_.get(d, P_);
  Archiving_Node::get_status(d);
  (*d)[names::recordables] = recordablesMap_.get_list();
}

inline
void iaf_psc_delta::set_status(const DictionaryDatum &d)
{
  Parameters_ ptmp = P_;  // temporary copy in case of errors
  const double delta_EL = ptmp.set(d); // throws if BadProperty
  State_      stmp = S_;  // temporary copy in case of errors
  stmp.set(d, ptmp, delta_EL);         // throws if BadProperty

  // We now know that (ptmp, stmp) are consistent. We do not 
  // write them back to (P_, S_) before we are also sure that 
  // the properties to be set in the parent class are internally 
  // consistent.
  Archiving_Node::set_status(d);

  // if we get here, temporaries contain consistent set of properties
  P_ = ptmp;
  S_ = stmp;
}

} // namespace

#endif /* #ifndef IAF_PSC_DELTA_H */