“Neighbouring” is defined in terms of embedding in a metric space and inverse-cube diffusion, rather than anything to do with graphic connectivity.

Also, these signals pile up in the synaptic cleft until they’re picked up, so it’s not just about instantaneous transmissivity as if these were radio signals.

But also also, other stuff like monoamine oxidase is floating about in its own diffusion patterns, cleaning up these signals.

It’s basically like a “scent” communication embodied-actor model, but a very complex one where things like redox reactions with the atmosphere occur.

Oh, and there are “secondary messengers”: signals that trigger other signals that, among other things, inhibit the release of the original signal when received back at the sender, such that an dynamic equilibrium state is reached between the two signal types.