Axel T. Brunger and coworkers have examined the mechanism of synaptic vesicle fusion and have proposed that fusion is initially inhibited until it is released by “calcium ion binding to synaptotagmin-C2 domains. . . fusion is [then] assisted by SNARE complex zippering and by active membrane remodeling properties of synaptotagmin.” Their article was published in Trends in Cell Biol., August 2018. The process of synaptic transmission was summarized as follows: “Synaptic transmission between pre- and post-synaptic neurons occurs when the pre-synaptic neuron terminal is temporarily depolarized upon an action potential, opening calcium ion channels near the active zones of synapses. Since the extracellular calcium ion concentration is much higher than the cytoplasmic concentration, calcium ion will flow into the cytoplasm. In turn, calcium ion will trigger fusion of neurotransmitter-filled synaptic vesicles with the presynaptic membrane in less than a millisecond. Upon fusion, neurotransmitter molecules are released into the synaptic cleft, and then bind to receptors that are located in the postsynaptic membrane.”
The authors described the complex machinery mechanism in considerable detail. It is a highly coordinated process that acts in mere milliseconds. Their proposal shows how synaptic fusion is kept from happening until calcium ion influx releases the inhibition. They state, “Taken together, synaptotagmin and synaptotagmin-like C2 domains may play a dual role of inhibiting a certain process, such as membrane fusion, in the absence of calcium ions, and of activating the same process after release of inhibition by membrane remodeling in the presence of calcium ions.”
It is reasonably apparent that design went into the creation of synaptic machines that function with extreme speed and efficiency. It is therefore reasonable to conclude that the design was that of our Creator God who made possible the personal communion between His Holy Spirit and our human spirit and souls/minds through the synaptic networks of the human brain.