So far, lu.i implemented a rather rudimentary synaptic interaction: While implementing a conductance-based stimulation (https://neuronaldynamics.epfl.ch/online/Ch13.S6.html), the impact of a presynaptic neuron was realized as a short, delta-like pulse, leading to almost step-like increments of the postsynaptic membrane potential.

More realistic synapse models feature more complex interaction kernels to realize, e.g., exponentially decaying synaptic currents

A direct comparison (taken from Billaudelle, 2022) of different interaction kernels showcases these more complex temporal dynamics and their impact on the shape of postsynaptic membrane potentials.

On April 14th, we submitted a new revision of lu.i, now incorporating such exponential synapses. The exponential current is generated by an additional leaky integrator stage with a tunable synaptic timeconstant. The revised version, furthermore, includes switches to configure a synapse to be excitatory or inhibitory (previously realized by swapping the jumper wires).

The updated fabrication files can be found on GitHub. We are currently awaiting delivery of the first batch of the new revision!