Chemical and electrical exchanges between neurons along dendrites and axons, and yes it can be dry words but they are what they are. The gap as empty space though isn't empty...extracellular fluid resides there like it does with all cells of the brain...mostly plasma.
Hmm...but in that very moment when chemical or electrical exchange occurs and the process jumps across the cleft, for one briefest instant we are 'floating free' so to speak...for a moment we are dormant and waiting for the exchange to occur so we can BE once more, and continue being with all these interactions of chemicals and electrical discharges.
I am wondering if what you are skirting about is that very brief instant when there is nothing but a wait for the process to complete itself...and what that brief moment is. As I put in that meditation topic, to let all senses fall away so that you are only a little piece of awareness in your brain basically has nothing but automatic functions occurring which we are not even aware of, and I guess that's the best I can do in comparing what occurs in that cleft...that gap...that brief moment of time when something is traversing from one location to another.
Quite the free-fall I guess. I wonder what we would know if we could slow ourself down enough to perceive that brief moment.