Hi Ali,

Currently, in NEST all delays are seen as purely dendritic, so the parameter "d" that Tony suggested to use can be used to model the dendritic delay of a connection between two neurons, which equals the total transmission delay. Please note that for most synapses, it is not required to model axonal delays, as the time a spike arrives at the synapse is only relevant for some special plasticity rules (such as spike timing dependent plasticity, see https://doi.org/10.1007/s00422-008-0233-1). In case you need to model both axonal and dendritic delays, please describe your use case so we can find a solution for you.

Best,
Jan