Facilitation

Facilitation 

in physiology, the intensification of a response to a simultaneous or preliminary stimulation of different parts of the same or another area or the sensory nerve fibers proceeding from the receptor. In facilitation based on an increase in excitability, a single stimulation increases the efficacy of a subsequent stimulation by paving the way for it. One stimulation thus facilitates another (hence the origin of the term). As a result of facilitation, subliminal stimulation, which by itself does not elicit a response, begins to have an effect when excitation develops in new focal centers. For example, the weak stimulation of the skin of a rabbit, insufficient to elicit a motor response, provokes a reflex upon the simultaneous electrical stimulation of the motor center of the brain’s cortex, which also does not produce an effect by itself. The concept of facilitation in the central nervous system was introduced in 1882 by the German physiologist S. Exner, who called the phenomenon Bahnung (German; “facilitation”). I. P. Pavlov noted that facilitation contributes to the formation of conditioned reflexes. If a temporary connection is established, facilitation occurs between two foci of excitation in the cortex of the cerebral hemispheres as a reaction to conditioned and unconditioned stimuli.