Developmental Research
P50 Sensory Gating
When our brains process stimuli, such as sound, the cells communicate by producing small electrical impulses. An EEG, or electroencephalogram, is a recording of that electrical activity which is displayed in the form of waves (brain waves). The p50 test that we do is a recording of your child's brain waves in response to a particular sound, or in other words, an auditory evoked potential recording. We record your child's response to a pair of clicks that sound like someone snapping his/her fingers. For most people the recordings show that their brain responds to the first click and has a much lower response to the second click. This occurs because the brain is wired to assume that repeated sounds are background noises and can generally be ignored. When the brain screens out the second sound, we say they “gate,” and when the person does not screen out the second sound we call this as “non-gating”. In other words, people that “gate” seem to be able to drown out background noise better then people that “do not gate”. Since this test must be done while a child is asleep, parents are asked to bring their child in for an overnight stay at Children's Hospital in Aurora. Parents will be allowed to sleep in the same room as their child.
Before the sleep P50, your child will be given a general physical to make sure he/she is in good health. In the evening, you and your child will check into The Children's Hospital where you will be sleeping overnight. Each room at Children's Hospital has two beds, one for you and one for your child, a private bathroom, and TV with On Demand movies. First, we will begin by setting up the test as follows:
- First we will clean your child's skin with alcohol pads and a mild exfoliant to remove oils from the skin.
- We will place eight electrodes on your child's face and head using a conductive paste and some cloth tape. Two of the electrodes will be placed behind the ears, one on the front of the forehead, two near one of the eyes, two under the chin, and one will be placed on the top of your head. Nothing comes through these wires to your head; these electrodes only record your brain waves.
Next, you and your child will be able to relax before falling asleep. During the course of the evening, a series of clicks will be played in the background through two speakers located near your child's head. In the morning, you will wake up at your normal time and check out. For this overnight visit, please bring any comfort items such as stuffed animals, blankets, books, etc. that will help your child feel more comfortable during the night.
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