There's a lot of other interesting biology besides propagation of electrical signals. Examples include: 1/ Transport of mRNAs (in specialized vesicle structures!) between neurons. 2/ Activation and integration of retrotransposons during brain development (which I have long hypothesized acts as a sort of randomization function for the neural field). 3/ Transport of proteins between and within neurons. This isn't just adventitious movement, either - neurons have a specialized intracellular transport system that allows them to deliver proteins to faraway locations (think >1 meters).