In GENESIS, a gap junction between compartments in two different cells can be implemented
by passing an RAXIAL message directly from each compartment to the other, with the Ra
field replaced by a number representing the resistance of the gap junction. However, this
simple approach cannot be used with the hsolve method, normally making it necessary to use
a very small time step when implementing gap junctions on a detailed cell model with many
small compartments. Carson B. Roberts has contributed this tutorial with example scripts
to illustrate a method for implementing gap junctions with hsolve.
Dendrodendritic connections between interneurons via gap junctions ("electical synapses")
are believed to facilitate synchronized firing in networks. (For example, see the 2009
Hjorth et al detailed striatal interneuron network model.) This effect is illustrated
with the non-hsolved method in "gapdemo", a simple example having two coupled cells that
is also included in this tutorial package (gap_junction_tutorial.tar.gz). The gapdemo
directory contains a descriptive README file and a simulation with a GUI.