Brain Rules for Baby Read Online Free PDF

during development, her body often senses trouble and deliberately induces a miscarriage. About 20 percent of pregnancies end in spontaneous abortion. Known environmental toxins, things you can actually monitor, account for only 10 percent of the birth defects observed in the lab.

A delicate web of cells, crackling with electricity
    Fortunately, most babies’ brains form just fine. The brain end of the neural tube continues its construction project by creating bulges of cells that look like complex coral formations. These eventually form the large structures of the brain. Before the first month, the baby’s tiny pre-brain cell has grown into a hefty army, millions of cells strong.
    The brain does not develop in isolation, of course. The early embryo temporarily displays gill arches around the fourth week, much like the ones fish have. These soon convert into face muscles and the throat structures that will allow your baby to speak. Your embryo next gets the stub of a tail but soon reverses course and resorbs the structure. There are strong evolutionary roots to our development, and we share this miracle with every other mammal on the planet. Except for one thing.
    Those bulges at the end of your embryo’s neural tube will turn into a great big, fat, super-smart brain—about the heaviest brain-per-body mass that exists on the planet. This massive structure is composed of a delicate spider web of cells, crackling with tiny bolts of electricity. Two types of cells are important here. The first type, glial cells, make up 90 percent of the brain cells inside your child’s head. They give the brain its structure and help the neurons correctly process information. It’s a good name; glial is a Greek word for glue. The second type of cell is the familiar neuron. Though they do a lot of your child’s thinking, neurons make up only about 10 percent of the total number of brain cells. That’s probably where we get the myth that you use only 10 percent of your brain.
     
    One neuron, 15,000 connections
    So how do cells turn into brains? Embryonic cells are manufactured into neurons in a process called neurogenesis. This is when the baby would like to be left alone, in the first half of pregnancy. Then, in the second half of pregnancy, the neurons migrate to the region
they eventually will call home and start wiring together. This is called synaptogenesis.
    Cell migration reminds me of when tracking bloodhounds are suddenly loosed from the sheriff’s truck to pick up the scent of a criminal. Neurons bolt out of their ectodermal cages, crawling over one another, sniffing out molecular cues, pausing, trying out different pathways, slithering helter-skelter throughout the developing brain. Eventually they stop, having arrived at a destination that may be pre-programmed into their cellular heads. They look around their new cellular digs and try to hook up with the neighbors. When they do, tiny, lively gaps between neural cells are created, called synapses (hence the term synaptogenesis). Electrical signals jump between the naked spaces to allow neural communication. This final step is the real business of brain development.
    Synaptogenesis is a prolonged process, for an easily understood reason: It is ridiculously complex. A single neuron has to make an average of 15,000 connections with the locals before its wiring job is over. Some neurons have to make more than 100,000 connections. That means your baby’s brain has to lash together an astonishing 1.8 million new connections per second to make a complete brain. Many of the neurons never complete the process. Like post-sex salmon, they simply die off.
    Even given this incredible speed, baby brains never make the birth deadline. About 83 percent of synaptogenesis continues after birth. Surprisingly, your baby girl’s brain will not completely finish its wiring until she is in her early 20s. Boys brains may take even longer. In humans, the brain is the last organ to finish