Enables inhibitory stdp

models/stdp_connection.h

@@ -68,6 +68,7 @@
 
   FirstVersion: March 2006
   Author: Moritz Helias, Abigail Morrison
+  Adapted by: Philipp Weidel
   SeeAlso: synapsedict, tsodyks_synapse, static_synapse
 */
 
@@ -327,6 +328,13 @@ STDPConnection< targetidentifierT >::set_status( const DictionaryDatum& d,
   updateValue< double_t >( d, "mu_plus", mu_plus_ );
   updateValue< double_t >( d, "mu_minus", mu_minus_ );
   updateValue< double_t >( d, "Wmax", Wmax_ );
+
+  // check if weight_ and Wmax_ has the same sign
+  if ( not( ( ( weight_ >= 0 ) - ( weight_ < 0 ) )
+         == ( ( Wmax_ >= 0 ) - ( Wmax_ < 0 ) ) ) )
+  {
+    throw BadProperty( "Weight and Wmax must have same sign." );
+  }
 }
 
 } // of namespace nest

models/stdp_triplet_connection.h

@@ -76,10 +76,12 @@
 
   FirstVersion: Nov 2007
   Author: Abigail Morrison, Eilif Muller, Alexander Seeholzer, Teo Stocco
+  Adapted by: Philipp Weidel
   SeeAlso: stdp_triplet_synapse_hpc, synapsedict, stdp_synapse, static_synapse
 */
 
-#include <cmath>
+// C-header for math.h since copysign() is in C99 but not C++98
+#include <math.h>
 #include "connection.h"
 
 namespace nest
@@ -195,16 +197,16 @@ class STDPTripletConnection : public Connection< targetidentifierT >
   inline double_t
   facilitate_( double_t w, double_t kplus, double_t ky )
   {
-    double_t new_w = w + kplus * ( Aplus_ + Aplus_triplet_ * ky );
-    return new_w < Wmax_ ? new_w : Wmax_;
+    double_t new_w = std::abs( w ) + kplus * ( Aplus_ + Aplus_triplet_ * ky );
+    return copysign( new_w < std::abs( Wmax_ ) ? new_w : Wmax_, Wmax_ );
   }
 
   inline double_t
   depress_( double_t w, double_t kminus, double_t Kplus_triplet_ )
   {
     double_t new_w =
-      w - kminus * ( Aminus_ + Aminus_triplet_ * Kplus_triplet_ );
-    return new_w > 0.0 ? new_w : 0.0;
+      std::abs( w ) - kminus * ( Aminus_ + Aminus_triplet_ * Kplus_triplet_ );
+    return copysign( new_w > 0.0 ? new_w : 0.0, Wmax_ );
   }
 
   // data members of each connection
@@ -355,6 +357,13 @@ STDPTripletConnection< targetidentifierT >::set_status(
   updateValue< double_t >( d, "Kplus_triplet", Kplus_triplet_ );
   updateValue< double_t >( d, "Wmax", Wmax_ );
 
+  // check if weight_ and Wmax_ has the same sign
+  if ( not( ( ( weight_ >= 0 ) - ( weight_ < 0 ) )
+         == ( ( Wmax_ >= 0 ) - ( Wmax_ < 0 ) ) ) )
+  {
+    throw BadProperty( "Weight and Wmax must have same sign." );
+  }
+
   if ( not( Kplus_ >= 0 ) )
   {
     throw BadProperty( "State Kplus must be positive." );

pynest/nest/tests/test_stdp_triplet_synapse.py

@@ -24,6 +24,7 @@
 import nest
 import unittest
 from math import exp
+import numpy as np
 
 
 @nest.check_stack
@@ -80,25 +81,27 @@ def status(self, which):
 
     def decay(self, time, Kplus, Kplus_triplet, Kminus, Kminus_triplet):
         """Decay variables."""
-        Kplus *= exp(- time / self.syn_spec["tau_plus"])
-        Kplus_triplet *= exp(- time / self.syn_spec["tau_plus_triplet"])
-        Kminus *= exp(- time / self.post_neuron_params["tau_minus"])
-        Kminus_triplet *= exp(- time /
+        Kplus *= exp(-time / self.syn_spec["tau_plus"])
+        Kplus_triplet *= exp(-time / self.syn_spec["tau_plus_triplet"])
+        Kminus *= exp(-time / self.post_neuron_params["tau_minus"])
+        Kminus_triplet *= exp(-time /
                               self.post_neuron_params["tau_minus_triplet"])
         return (Kplus, Kplus_triplet, Kminus, Kminus_triplet)
 
     def facilitate(self, w, Kplus, Kminus_triplet):
         """Facilitate weight."""
-        return w + Kplus * (
+        Wmax = self.status("Wmax")
+        return np.sign(Wmax) * (abs(w) + Kplus * (
             self.syn_spec["Aplus"] +
-            self.syn_spec["Aplus_triplet"] * Kminus_triplet
+            self.syn_spec["Aplus_triplet"] * Kminus_triplet)
         )
 
     def depress(self, w, Kminus, Kplus_triplet):
         """Depress weight."""
-        return w - Kminus * (
+        Wmax = self.status("Wmax")
+        return np.sign(Wmax) * (abs(w) - Kminus * (
             self.syn_spec["Aminus"] +
-            self.syn_spec["Aminus_triplet"] * Kplus_triplet
+            self.syn_spec["Aminus_triplet"] * Kplus_triplet)
         )
 
     def assertAlmostEqualDetailed(self, expected, given, message):
@@ -109,6 +112,7 @@ def assertAlmostEqualDetailed(self, expected, given, message):
 
     def test_badPropertiesSetupsThrowExceptions(self):
         """Check that exceptions are thrown when setting bad parameters."""
+
         def setupProperty(property):
             bad_syn_spec = self.syn_spec.copy()
             bad_syn_spec.update(property)
@@ -201,6 +205,7 @@ def test_weightChangeWhenPrePostSpikes(self):
         Kminus = 0.0
         Kminus_triplet = 0.0
         weight = self.status("weight")
+        Wmax = self.status("Wmax")
 
         (Kplus, Kplus_triplet, Kminus, Kminus_triplet) = self.decay(
             2.0, Kplus, Kplus_triplet, Kminus, Kminus_triplet)
@@ -239,6 +244,7 @@ def test_weightChangeWhenPrePostPreSpikes(self):
         Kminus = 0.0
         Kminus_triplet = 0.0
         weight = self.status("weight")
+        Wmax = self.status("Wmax")
 
         (Kplus, Kplus_triplet, Kminus, Kminus_triplet) = self.decay(
             2.0, Kplus, Kplus_triplet, Kminus, Kminus_triplet)
@@ -288,13 +294,57 @@ def test_maxWeightStaturatesWeight(self):
             "weight"), "weight should have been limited")
 
 
+@nest.check_stack
+class STDPTripletInhTestCase(STDPTripletConnectionTestCase):
+
+    def setUp(self):
+        nest.set_verbosity('M_WARNING')
+        nest.ResetKernel()
+
+        # settings
+        self.dendritic_delay = 1.0
+        self.decay_duration = 5.0
+        self.synapse_model = "stdp_triplet_synapse"
+        self.syn_spec = {
+            "model": self.synapse_model,
+            "delay": self.dendritic_delay,
+            # set receptor 1 post-synaptically, to not generate extra spikes
+            "receptor_type": 1,
+            "weight": -5.0,
+            "tau_plus": 16.8,
+            "tau_plus_triplet": 101.0,
+            "Aplus": 0.1,
+            "Aminus": 0.1,
+            "Aplus_triplet": 0.1,
+            "Aminus_triplet": 0.1,
+            "Kplus": 0.0,
+            "Kplus_triplet": 0.0,
+            "Wmax": -100.0,
+        }
+        self.post_neuron_params = {
+            "tau_minus": 33.7,
+            "tau_minus_triplet": 125.0,
+        }
+
+        # setup basic circuit
+        self.pre_neuron = nest.Create("parrot_neuron")
+        self.post_neuron = nest.Create("parrot_neuron", 1,
+                                       params=self.post_neuron_params)
+        nest.Connect(self.pre_neuron, self.post_neuron, syn_spec=self.syn_spec)
+
+
+def suite_inh():
+    return unittest.makeSuite(STDPTripletInhTestCase, "test")
+
+
 def suite():
     return unittest.makeSuite(STDPTripletConnectionTestCase, "test")
 
 
 def run():
     runner = unittest.TextTestRunner(verbosity=2)
     runner.run(suite())
+    runner.run(suite_inh())
 
 if __name__ == "__main__":
     run()