What’s new in NEST 3.4

This page contains a summary of important breaking and non-breaking changes from NEST 3.3 to NEST 3.4. In addition to the release notes on GitHub, this page also contains transition information that helps you to update your simulation scripts when you come from an older version of NEST.

If you transition from a version earlier than 3.3, please see our extensive transition guide from NEST 2.x to 3.0 or release updates for previous releases in 3.x.

Documentation restructuring and new theme

NEST documentation has a new theme! We did a major overhaul of the layout and structure of the documentation. The changes aim to improve findability and access of content. With a more modern layout, our wide range of docs can be discovered more easily. The table of contents is simplified and the content is grouped based on topic (neurons, synapses etc) rather than type of documentation (e.g., ‘guides’).

Query spatially structured networks from target neuron perspective

PyNEST now provides functions GetSourceNodes(), GetSourcePositions(), and PlotSources() which allow you to query or plot the source neurons of a given target neuron.

Changes in NEST behavior

Inferred extent of spatial layers with freely placed neurons

Spatial layers can be created by specifying only the node positions using spatial.free, without explicitly specifying the extent. In that case, in NEST 3.4 and later, the extent will be determined by the position of the lower-leftmost and upper-rightmost nodes in the layer; earlier versions of NEST added a hard-coded padding to the extent. The center is computed as the midpoint between the lower-leftmost and upper-rightmost nodes.

When creating a layer with only a single node, the extent has to be specified explicitly.

Disconnect with SynapseCollection

It is now possible to disconnect using a SynapseCollection, which removes only the connections obtained by calling GetConnections(). The SynapseCollection can either be passed to nest.disconnect(), or one may call the member function disconnect() of the SynapseCollection.

Removal of deprecated models

The models iaf_psc_alpha_canon and pp_pop_psc_delta have long been deprecated and were now removed from NEST. In case you depend on them, you will find similar functionality in the replacement models iaf_psc_alpha_ps and gif_pop_psc_exp, respectively.

Deprecation information

Model spike_dilutor is now deprecated and can only be used in single-threaded mode. To implement connections which transmit spikes with fixed probability, use bernoulli_synapse instead.