When a constant stimulus, such as an electric current, is applied to a nerve, the excitability of the nerve under the cathode, or negative electrode, increases quickly. With continued stimulation by current flow, there is a slow decrease in nerve excitability, known as accommodation, followed by a sudden drop when the current is stopped. Following cessation of the stimulating current, the nerve briefly becomes less sensitive to stimulation than it was before the current was turned on. Following a resting period, the original level of excitability tends to be restored. During the adaptation period, or time of decrease in excitability, it may be possible to stimulate the nerve by changing either the length or strength of the stimulus.
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