The Postsynaptic Neuron II: The Neuron as an Integrative Device

Abstract

Ramón y Cajal, the great Spanish neuroanatomist, enunciated the neuron doctrine at the end of the nineteenth century. This states that the nerve cell is the structural (cellular) and functional unit of the nervous system. From his doctrine he inferred the law of dynamic polarisation, namely that all neurons are dynamically polarised such that excitation can only be transmitted from the axon of one neuron to the dendrites or soma of another, and, within a neuron, this excitation travels from the dendritic pole to the axonal pole. The doctrine and the law provided the basis for theories of the nervous system and was supported by the classic work of the British physiologist Sir Charles Sherrington. With the advent of electrophysiological techniques, especially their use by Eccles and his collaborators in the stydy of mammalian motoneurons, it seemed that these ideas were fully validated.