Key Terms. cholinergic: Pertaining to, activated by, producing, or having the same function as acetylcholine.; postsynaptic neuron: The nerve cell that bears receptors for neurotransmitters released into the synaptic cleft by the presynaptic neuron.; preganglionic fiber: In the autonomic nervous system, fibers from the CNS to the ganglion are known as preganglionic fibers.