Types
At any given moment, a neuron may be receiving postsynaptic potentials from thousands of other neurons. Whether or not threshold is reached, and an action potential generated, is dependent upon the spatial (from multiple neurons) and temporal summation (from a single neuron) of all inputs at that moment. In addition, the summation of excitatory and inhibitory influences will modulate the outcome. The closer a synapse is to the cell body of a neuron, the greater the influence on the final summation. This is due to the fact that the postsynaptic potentials travel through the unmyelinated dendrites to the axon hillock, where they are combined in summation. Because dendrites are unmyelinated the sustained membrane potential decreases increasingly over the amount of distance travelled.
Read more about this topic: Summation (neurophysiology)
Famous quotes containing the word types:
“He’s one of those know-it-all types that, if you flatter the wig off him, he chatter like a goony bird at mating time.”
—Michael Blankfort. Lewis Milestone. Johnson (Reginald Gardner)
“As for types like my own, obscurely motivated by the conviction that our existence was worthless if we didn’t make a turning point of it, we were assigned to the humanities, to poetry, philosophy, painting—the nursery games of humankind, which had to be left behind when the age of science began. The humanities would be called upon to choose a wallpaper for the crypt, as the end drew near.”
—Saul Bellow (b. 1915)
“If there is nothing new on the earth, still the traveler always has a resource in the skies. They are constantly turning a new page to view. The wind sets the types on this blue ground, and the inquiring may always read a new truth there.”
—Henry David Thoreau (1817–1862)