neuron + logos

Greek neuron meant sinew, cord, or string — referring to tendons and other cord-like structures in the body. Ancient anatomists were uncertain about the function of the pale, fibrous structures that ran from the brain and spinal cord throughout the body. Galen believed nerves were hollow tubes carrying pneuma (animal spirits) from the brain to the muscles. This pneumatic model persisted for 1,400 years.

The modern understanding of nerves as electrical signal conductors began with Luigi Galvani's 1780 demonstration that electrical stimulation caused muscle contraction in frog legs. Alessandro Volta's battery (1800) made electrical experimentation reproducible. Emil du Bois-Reymond's 1840s studies established the electrical nature of nerve impulses. The pneuma in the hollow tubes was replaced by electrical potential.

Jean-Martin Charcot, practicing at the Salpêtrière hospital in Paris from the 1860s to 1890s, created clinical neurology as a systematic discipline — using careful clinical observation to correlate specific symptoms with specific brain and nerve lesions found at autopsy. His Tuesday lectures, attended by Freud and by artists and writers across Paris, made neurology a cultural as well as medical event.

Modern neuroscience has extended neurology into molecular biology, genetics, and imaging technologies. MRI, PET scans, and functional brain imaging have made it possible to watch the living brain in operation. The Greek word for sinew and cord now names a field studying 86 billion neurons connected by 100 trillion synapses.