Neuron doctrine
The principle that the nervous system is composed of discrete cells, rather than a continuous network, that communicate at specialized junctions.
Santiago Ramón y Cajal: A Spanish neuroscientist whose detailed drawings of nervous tissue established neurons as discrete cells. His observations supplied the strongest early anatomical case for cellular independence.
Neuron: An electrically excitable cell that receives, processes, and transmits information through electrical and chemical signals. Neurons are the discrete cellular units asserted by the doctrine.
Cell theory: The biological principle that living organisms are composed of cells, the basic units of structure and function. The neuron doctrine applies cell theory specifically to the nervous system.
Electrical synapse: A junction where cells exchange ionic current directly through intercellular channels called gap junctions. Direct electrical coupling complicates, but does not erase, cellular separateness.
Camillo Golgi: An Italian physician who developed a silver-staining method that reveals individual nerve cells. His staining method enabled the observations that supported the doctrine, though he opposed its conclusion.
Synapse: A junction where one neuron communicates with another cell, usually by chemical or electrical signaling. Synapses provide the contact points through which separate neurons communicate.
Neuroscience: The scientific study of the nervous system, including its structure, function, development, and disorders. The doctrine established cellular organization as a foundation for the field.
Gap junction: A channel connecting neighboring cells and allowing ions and small molecules to pass between their cytoplasms. Gap junctions create limited cytoplasmic continuity between otherwise distinct cells.
Reticular theory: The theory that nervous tissue forms a continuous interconnected network rather than distinct cellular units. It was the direct rival to the neuron doctrine in debates over nervous-system structure.
Dendrite: A branched neuronal projection that receives synaptic input and conveys it toward the cell body. Dendrites illustrate how a neuron gathers signals from other cells.