The basic unit of the nervous system — a single elongated cell that propagates an electro-chemical impulse — and the building-brick of every neural model.
Young describes the real neuron and its all-or-none firing, then reviews a generation of attempts to build artificial ones — iron-wire models, neon-lamp fibres, transistor and tunnel-diode “neuristors.”
George idealises the neuron into an “element” obeying defined rules, the basic building-brick from which neural nets and biological models are assembled.