weight_recorder – Recording weights from synapses¶
Description¶
The change in synaptic weights over time is a key observable property in
studies of plasticity in neuronal network models. To access this information, the
weight_recorder can be used. In contrast to other recording
devices, which are connected to a specific set of neurons, the weight
recorder is instead set as a parameter in the synapse model.
After assigning an instance of a weight recorder to the synapse model
by setting its weight_recorder property, the weight
recorder collects the global IDs of source and target neurons together
with the weight for each spike event that travels through the observed
synapses.
To only record from a subset of connected synapses, the
weight recorder accepts NodeCollections in the parameters senders and
targets. If set, they restrict the recording of data to only
synapses that fulfill the given criteria.
>>> wr = nest.Create('weight_recorder')
>>> nest.CopyModel("stdp_synapse", "stdp_synapse_rec", {"weight_recorder": wr})
>>> pre = nest.Create("iaf_psc_alpha", 10)
>>> post = nest.Create("iaf_psc_alpha", 10)
>>> nest.Connect(pre, post, syn_spec="stdp_synapse_rec")
Recording time window¶
The time span during which the recorder actively records can be
specified using the properties start and stop. These define
the recording period of the device in ms. An additional property
origin allows to shift the recording window by a certain time,
which can be useful in experimental protocols with repeated
simulations. Please note that events with
timestamp t = start are not recorded.
Data handling¶
All recorded data is handed over to the recording backend, selected
via the record_to property. More details on available backends and
their properties can be found in the guide to recording from
simulations.
Recorder properties¶
- label
A string (default: “”) specifying an arbitrary textual label for the device. Recording backends might use the label to generate device specific identifiers like filenames and such.
- n_events
The number of events that were collected by the recorder can be read out of the n_events entry. The number of events can be reset to 0. Other values cannot be set.
- origin
A positive floating point number (default : 0.0) used as the reference time in ms for start and stop.
- record_to
A string (default: “memory”) containing the name of the recording backend where to write data to. An empty string turns all recording of individual events off.
- start
A positive floating point number (default: 0.0) specifying the activation time in ms, relative to origin.
- stop
A floating point number (default: infinity) specifying the deactivation time in ms, relative to origin. The value of stop must be greater than or equal to start.