Nervous system would not exist without the human brain. Most neurons send signals via their axons, although some types are capable of dendrite-to-dendrite communication. (In fact, the types of neurons called amacrine cells have no axons, and communicate only via their dendrites.) Neural signals propagate along an axon in the form of electrochemical waves called action potentials, which produce cell-to-cell signals at points where axon terminals make synaptic contact with other cells. Synapses may be electrical or chemical. Electrical synapses make direct electrical connections between neurons, but chemical synapses are much more common, and much more diverse in function. At a chemical
Pinky and the Brain Labs research facility. Brain is self-centered and scheming, Pinky is good-natured but feebleminded. In each episode, Brain devises a new plan to take over the world which ultimately ends in failure: usually due to Pinky's idiocy, the impossibility of Brain's plan, Brain's own arrogance, or just circumstances beyond their control. In common with many other "Animaniacs" shorts, many episodes are in some way a parody of something else, usually a film or novel. Many of the "Pinky and the Brain" episodes occur in the 1990s at Acme Labs, located in some large American city underneath a suspension bridge. Several episodes