Topological Connections
From NEST
Contents |
What is a topological connection?
A topological connection is a connection whos nature is decided by the spatial position of the nodes involved in the connection.
 Basic connection graph |
 Connection graph with spatial reference |
In NEST a topological connection is created by first placing a set of nodes into one or several spatial layers (or subnets), and then connecting the layers to each other. The module responsible for these actions must be loaded with the topology using command.
topology using
How to create spatial layers
A layer is created with the CreateLayer command. The layout of the layer should be defined in a input dictionary to the command.
<< /positions [[0.3 0.4] [-0.2 0.25] [0.7 0.0] [-0.9 -0.4]]
/extent [2.0 1.0]
/elements /iaf_neuron
>> CreateLayer
How to connect layers
Layers are connected with the ConnectLayer command. The command takes three inputs; one source layer, one target layer and one dictionary.
<< /rows 9
/columns 18
/extent [2.0 1.0]
/elements /iaf_neuron
>> /layer_dict Set
layer_dict CreateLayer /src Set layer_dict CreateLayer /tgt Set
<< /connection_type (convergent)
/mask << /circular << /radius 0.5 >> >>
/weights << /gaussian << /sigma 0.4 >> >>
>> /connection_dict Set
src tgt connection_dict ConnectLayer
How to print an overview of the spatial connections
The command PrintLayerConnections can be used to get a summary of the connections and their spatial attributes. The command accepts three inputs; one filestream, one layer GID and one synapse type.
(out.sli) (w) file layer_gid /static_synapse PrintLayerConnections
More info
A complete user manual for the topology module can be found in the NEST tarball folder topology/doc/
