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--- tutorials:writing_your_own_plasticity_model [2016/08/18 16:52] – Updates links zenke
+++ tutorials:writing_your_own_plasticity_model [2016/08/18 16:54] – [Synaptic traces] zenke
@@ Line 37: / Line 37: @@
 The macros ''DEFAULT_TRACE_MODEL'' and ''PRE_TRACE_MODEL'' are defined in ''auryn_definitions.h'' to facilitate the change of the underlying integration scheme. Per default they refer to [[manual:EulerTrace]], because Euler integration is most efficient in most situations (see [[http://journal.frontiersin.org/article/10.3389/fninf.2014.00076/abstract|Zenke and Gerstner (2014)]] for details).
-This declaration should be matched in the ''.cpp'' file by
+This declaration should be matched in the ''.cpp'' file. Typically there should be an init function in your plastic connection class in which you can write:
 <code c++>
 /* Initialization of presynaptic traces */
@@ Line 47: / Line 47: @@
 tr_post_hom = dst->get_post_trace(tau_hom);
 </code>
-which initializes the traces using their respective timeconstants tau_* and registers them to either the presynaptic (''src'') or the postsynaptic (''dst'') [[manual:NeuronGroup]] respectively. By doing so, the traces will be automatically incremented by one upon each spike of the corresponding [[manual:NeuronGroup]]. Moreover, if multiple [[manual:Connection]] objects were to define a trace with the same timeconstant for the same [[manual:NeuronGroup]], Auryn knows about this and internally only computes the trace once.
+which initializes the traces using their respective time constants tau_* and registers them to either the presynaptic (''src'') or the postsynaptic (''dst'') [[manual:NeuronGroup]] respectively. By doing so, the traces will be automatically evolve (decay over time) and be incremented by one upon each spike of the corresponding [[manual:NeuronGroup]]. Moreover, if multiple [[manual:Connection]] objects were to define a trace with the same time constant for the same [[manual:NeuronGroup]], Auryn 'knows' about this and internally only computes the trace once to speed up computation. The current value of a trace can then be accessed in the code via ''tr_post->get(NeuronID id)'' which we will use in the next section to compute weight updates.
-The current value of a trace can then be accessed in the code via ''tr_post->get(NeuronID id)'' which we will use in the next section to compute weight updates.
 ==== Weight updates at spiking events (propagate) ====