The Baby's Brain

Summary of “Life of Brain”, by Kathleen McAuliffe, Discover, June 30, 2007

Amniotic fluid is an excellent conductor of sound so that before birth, babies are attuned to the rhythm of the mother’s voice. Cultural assimilation begins before birth, impacting on the music liked and food chosen. Before birth we have many more brain cells and connections than we use as adults. Birth sparks more growth with new sights, sounds and sensations. Sights, sounds and touches are all activated together and the infant can’t tell which organ they come from. It is only with time and experience that they distinguish the inputs from the different sense organs. Heavily used pathways become coated in a fatty substance called myelin, which speeds transmission of information within the brain. Rarely used connections wither and die.

Half of the neural circuits toddlers have vanish by adulthood. There are “sensitive periods” in the brain when it is most receptive to stimulation. Infants are fascinated by anything that resembles a face. Newborns don’t see very well, but can see objects within a yard like an out-of-focus photo. By six months a baby can distinguish novelty in faces, but there is a window of time in infancy when the baby must be exposed to faces in order to become expert at distinguishing one face from another. Babies from four months old respond to different facial expressions. Real people’s faces work much better than photos.

Babies have the ability to perceive all of the basic sound units of all of the world’s languages. This facility is lost between 6 –12 months as circuits shrivel from disuse. Adults learning Hindi needed a year of training to make certain phonetic distinctions that a newborn readily makes. The key for a baby is watching a live speaker speak. Infants are more alert in social situations and learn meaning by following eye gaze. If no one engages them they treat language as if it were noise and tune it out. During the first year of life, as the baby goes from cooing to babbling to uttering the first word, parts of the brain that understand and produce speech begin to link up, babies drawing the connections between the movements of their lips and tongue and the sounds they make, allowing speech mimicry.

Our first memory dates from age 3 or 4 because the various parts of the brain are not yet connected, the reason we do not remember our infancy. If a child does not get appropriate sensory inputs at this early age or if the developmental process goes awry the result can be a “very funky wiring system”. The malleability of the young brain is a double edged sword. Learning occurs at a breathtaking pace but can be a liability if something goes wrong or the input is not what it should be.

Parents are the sculptors of their baby’s brain. Nothing beats hugs, kisses and lots of fun together.