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:
“Science is intimately integrated with the whole social structure and cultural tradition. They mutually support one other—only in certain types of society can science flourish, and conversely without a continuous and healthy development and application of science such a society cannot function properly.”
—Talcott Parsons (1902–1979)
“The rank and file have let their servants become their masters and dictators.... Provision should be made in all union constitutions for the recall of leaders. Big salaries should not be paid. Career hunters should be driven out, as well as leaders who use labor for political ends. These types are menaces to the advancement of labor.”
—Mother Jones (1830–1930)
“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)