We are motivated by previous experience with the silicon retina, which required thirteen different cell types, each of which had to be hardwired explicitly. Now since there are a million fibers leaving the retina through the optic tract for the brain, a structure which has on the order of a trillion neurons, each of which averages a thousand synaptic contacts, we would like to find a more efficient method for modeling this system than tracing every connection!

http://www.stanford.edu/group/brainsinsilicon/Brian_bio_N1.html

 

T-Spice is a competent transistor simulator but it chokes on some obviously ridiculous user-designed devices like a hexagonal monolithic charge-diffusing lattice. So we can't simulate the most important feature of our design. Fortunately, we can still simulate all of the surrounding circuitry and fudge the monolithic lattice by substituting a discrete transistor network with the same topology.