(or electrical stimulation), the administration of electric current in specified doses to organs or systems of an organism in order to stimulate the action of the organs or systems. It is carried out by means of electronic stimulators and is employed most frequently for skeletal muscles, nerve trunks, and the cardiac muscle (in the event of disturbances of the normal heart rhythm).

To stimulate muscles and nerve trunks, the current is fed through electrodes placed at the most excitable (motor) points of the muscle or nerve. Through periodic stimulation, the muscles are caused alternately to contract and relax. Rhythmic pulses of gradually increasing intensity are used to treat severely dener-vated skeletal muscles. If the muscles have not totally lost their ability to contract, electrostimulation is used to supplement or intensify the action of the natural mechanisms that cause the dener-vated muscles to contract; electrostimulation furthers the restoration of the normal functioning of the muscles. In present-day diagnosis of muscle and nerve lesions that result in motor disturbances, electrostimulation is combined with the recording of action currents of the muscles.

Electrostimulation of the heart is done by both direct and indirect methods. In direct stimulation, the stimulating pulses are fed directly to the heart. In indirect stimulation, the pulses are fed through, for example, needle electrodes or electrodes placed on the skin. Electronic cardiac pacemakers are used to promote normal conduction of excitation in the heart. Such pacemakers are implanted under the skin. At fixed intervals after the contraction of the left atrium they supply artificial pulses for the direct stimulation of the left ventricle.

Surgeons use electrostimulation of internal organs to treat lesions of the spinal cord. Electrostimulation is also employed to restore the normal action of the urinary bladder and sphincter, to restore the secretory and motor functions of the gastrointestinal tract, and to restore the nutrition of tissues impaired by decubitus ulcers.

Electrostimulation of the brain is widely used in physiology to study the functions of various parts of the central nervous system. Here, electrodes are implanted at certain points of the brain. In animal experiments where electric signals are fed to the brain by the animals themselves (seeSELF-STIMULATION), points, known as pleasure centers, have been found that the animals stimulate with particular eagerness. When certain other parts of the brain are electrically stimulated, the behavior of the animals is altered. In neurosurgery, electrostimulation of the human brain is used to detect foci of pathological excitation that cause, for example, epileptic seizures and nonepileptic hyperkinesia. Electrostimulation may involve the implantation of electrodes deep in the brain or may be performed in single-stage operations. In the USSR, electrostimulation of the human brain is used only in the presence of specific clinical indications for the procedure.