Electrical Stimulation of the Brain (ESB)
A procedure which involves the introduction of a weak electrical current into specific locations in the brain by using multiple microelectrodes to apply short pulses of electrical currents intended to mimic the natural flow of impulses through the neural pathways.
Electrical stimulation of the brain (ESB) is useful in a variety of situations, including neurosurgical operations and experimental research. In neurosurgery, this procedure may be used to assist physicians in determining which brain tissue should be removed. Because the patient must remain awake during the procedure, only a local anesthetic is administered. Focal epilepsy has been surgically treated by using electrical brain stimulation in conscious patients to determine the epileptic focus.
In experimental research, ESB does not control complex behavior patterns such as depression, but it can be employed quite successfully to control individual functions. Therefore, this procedure has proven useful in studying the relationships among various areas and structures of the brain and the activities they control. It has been found, for example, that stimulation of the visual cortex produces visual sensations, such as bursts of light or color (blind people have seen spots of light as a result of ESB). Similarly, stimulation of the auditory cortex results in aural sensation, while stimulating areas associated with motor control produces arm, leg, or other body movements. Stimulation of areas of the brain linked to association can induce memories of scenes or events.
In addition to research and experimental uses, electrical brain stimulation has been successfully used for some therapeutic purposes. Brain stem and cerebellar stimulation have aided in some movement disorders; peroneal nerve stimulation has been used to treat dropfoot in stroke victims; and transcutaneous nerve, dorsalcolumn, and deep-brain stimulation have proven useful in the relief of chronic severe pain.
Electrical brain stimulation has aided in mapping connections between different regions of the brain in animals, and has been used to induce many different types of behavior in animals, including eating, drinking, aggression, hoarding, and both sexual and maternal behavior. While hypothalamic stimulation is associated with such emotional responses as attack and defense, stimulation of the reticular formation in the brain stem can induce sleep. ESB has also confirmed the existence of a "reward center" in animals, whereby animals can be taught to stimulate their own brains mechanically by pressing a lever when such stimulation results in a pleasant sensation.