I like to think of Na+, K+, Ca++ and the corresponding myriad of channels as the colors that our neurons are using to paint their pictures. So many non-linearities, so many effects (from geometry to channel electrophysiology) that it seems like a never-ending battle to comprehend our brain, but a fun a battle at least. :)

Do you think there are other mechanisms involved in neural signal processing then action potentials and synaptic mechanisms? Do you think that the electric field generated by a given small region can have a significant effect on another region so that we should include them in network simulations?