Neurons and the Neuron Doctrine

Although the neuroglia has far greater importance than we accord it, nerve cells are regarded as the fundamental genetic, anatomical, functional, and trophic (nutritive, sustaining) units of the nervous system. These attributes are the four tenets of the neuron doctrine, a once-controversial, ever-authoritative, and still-evolving restatement of the cell theory first applied to nervous tissue in 1891. Fifth and sixth tenets were quick to follow.

In 1890, the histologist Santiago Ramon y Cajal, considering neurons as separate cells and tirelessly delineating their connections, inferred that impulse traffic in a neuron flows one way: from dendrites and soma to axon and axon terminals or from receptor parts to effector parts. In 1897, the physiologist Charles Sherrington proposed the term synapse for the contact between nerve cells and suggested that the one-way sensorimotor traffic in spinal reflexes rested on a one-way valvelike action of the synapse. So a fifth tenet, Cajal's law of dynamic polarization (like neuron doctrine, strong words), was added and then a sixth, his law of connectional specificity: synapses are not random, but determined.

Conquering Fear In The 21th Century

Conquering Fear In The 21th Century

The Ultimate Guide To Overcoming Fear And Getting Breakthroughs. Fear is without doubt among the strongest and most influential emotional responses we have, and it may act as both a protective and destructive force depending upon the situation.

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