Developmental Research
Sensory Gating p50
Our brains are designed to ignore or screen out repetitive sounds (so we don’t hear the fan always running in the background or the refrigerator turning on and off). Instead, our brains are designed to focus on new or novel sounds. We can measure whether the brain is identifying new sounds and screening out old sounds by measuring brain waves through electroencephalography or EEG. We are interested in the age at which infants' brains can accurately screen out repetitive sounds and what other influences (genetics, exposure to tobacco, etc) affect this ability.
The brain's ability to respond to new sounds and screen out repetitive sounds works as well in dream sleep as it does while we are awake. We measure the brain waves of sleeping infants who are listening to sounds. This procedure is scheduled when infants are tired and ready to sleep. A trained member of our research team cleans the areas where the electrodes will be placed: behind both the infant's ears, by the right eye, under the infant's chin, and a small spot on the center of the head. The cleaning process entails the gentle administration of a mild abrasive cream, similar to an exfoliant and an alcohol preparation pad. The research assistant proceeds to place a cap, similar to a baby bonnet, onto the infant's head. This cap contains electrodes that do not hurt the child, but allow us to record the infant's brain waves. Each electrode is attached to a wire that is able to read the brain waves of the infant and the various muscle movements near the eye and under the chin (this helps us know when the baby is dreaming). While the baby sleeps, we play clicking noises, which are no louder than street traffic, through speakers behind the infants head. We record the infant's brain waves as long as we are able (usually until the baby wakes up). Most babies are done within three to four hours, and this procedure often takes even less time to complete. As a thank you for participating, parents are compensated for their time.
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