This test records electrical activity from the brain, spinal nerves, or sensory receptors in response to specific external stimulation. Electrodes are applied to the scalp and other areas of the body and a series of stimuli is introduced. Hundreds to thousands of responses are received, amplified, and averaged by a computer. Evoked potentials are helpful in evaluating a number of different neurological problems, including multiple sclerosis, spinal cord injuries, acoustic neuroma, and optic neuritis. Each type of EP looks at a different neurological pathway: auditory, visual, and somatosensory.