A nerve transmission consists of an message pushingom into the where they bind or dock with -. Once they bind like a key in a lock, they start another message and then they sucked back into the -synaptic neuron for re-use. The limbic system is the and center of the brain. is the primary neurotransmitter in the limbic system. The fasciculus retroflexus is a track of cells that connects the limbic system with the pre-frontal cortex. It is the center for-.