November 1999

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What's Going On In There?
Exploring the Brave New Brain

by Daphne Frostchild

What's Going On In There? How the Brain and Mind Develop in the First Five Years of Life
Lise Eliot, Ph.D.
Bantam Books
534 pp.
$26.95 order now logo

Why are humans born with brains that are not fully developed?

Lise Eliot's book-length answer has far-reaching consequences for how we raise our children: we are born without fully developed brains, she writes, because the brain's development must be driven by our experience of and adaptation to our environment.

In the process of justifying her claim, Eliot presents a wealth of neuroscience's experimental results in a manner most laymen will have no trouble grasping.


Brain Development

Since she sees the brain / mind development as a continuum, Eliot begins her study with an in-depth description of the development of the nervous system from the moment of conception.

Babies' brains mature from bottom to top--the lower functions first, reasoning last. (The process continues into the teenage years.) As Eliot observes, human fetuses develop similarly to other phylogenically related species, demonstrating the "conservative nature of evolution." In other words, we initially develop as other animals do, and changes that are species-specific are added on at the end of the developmental process.

Brains develop as the zygote's neural plate transforms into the central nervous system of brain, spinal column and nerves. The basic brain structure is formed by four months. Brain cells (or neurons) are formed at an average rate of 250,000 per minute throughout the nine months of gestation (the highest actual rate is 500,000 per minute early in development, when most are created).

After formation, neurons migrate to function-specific positions. Synaptogenesis, the process of forming synapses (or connections) between brain cells, begins at two months' gestation and continues to two years after birth, at a rate of 1.8 million connections per second. Each cell must also grow dendritic branches. Dendrites grow nobbins (dendritic spikes) to accommodate the synapses. The growth of dendrites triples the thickness of the cerebral cortex in the first year.

Myelination, the production of a lipid / protein which coats each brain cell, enables the conductivity of cells. In fact, until cells are myelinated, they are very poor at conducting information. As Eliot points out, diet plays a key role in myelination, especially in early childhood. Poor nutrition (such as low fat intake) leads to poor brain function.

Each time a particular neuron is used, it is chemically excited, cementing the connections between neurons (across the synapse) from axon to dendrite. Repeated connections are kept; others are pruned. This, Eliot argues, is where nurture plays a key role in all areas of brain development.

Of course, the developing nervous system faces many dangers. A genetically normal baby that is exposed to hazardous substances, for instance, could be born with nervous system defects. But hazardous substances don't necessarily effect all areas of the developing brain. Since each separate function of the brain develops at specific times, avoidance is largely a timing issue. (Eliot includes a useful summary chart of pathogens.)

Birth itself is stressful and potentially dangerous, if the baby is deprived of oxygen for too long. However, Eliot writes, birth is usually a positive experience for newborns, clearing their lungs for normal breathing and releasing stress hormones that help them adjust to their new environment.


Development of the Senses

After the basic structures of the brain are formed, the senses begin to develop. This is a particularly important stage, because the senses allow input into the brain and actually determine how the brain evolves.

Touch is the first sense to develop during gestation. As Eliot notes, it encompasses four types of sensory abilities: cutaneous sensation (touch on the skin), temperature, pain and proprioception (sense of position and movement in one's body). These are all functional at birth. Cortical size, as well as emotional well-being, can be increased by tactile stimulation (baby massage, playing with toys, exposure to different textures).

The vestibular system, which controls reflex and motor skills, is located inside the middle ear. This sense is important to the development of other brain functions because the earlier babies can explore the world, the quicker they will learn.

Smell is a primitive sense, and it is extremely important to other mammals. In humans, it is mature at birth. Fetuses can smell in the womb during the last trimester. This promotes bonding of the infant to the mother after birth. Infants also recognize the smell of their mother's breast.

Fetuses are also capable of tasting in the womb. Taste preference is malleable, but all babies prefer sugar since it satisfies their taste abilities at birth. Eating sweet foods releases endogenous opiates in the brain that induce a sense of pleasure and well-being. Sour-preferring cells in the tongue are the last to develop. (Eliot's examination of food requirements and how they differ for children and adults is particularly thorough.)

Vision, on the other hand, is poor in humans at birth. Many other animals have better vision at birth because it is beneficial in species that require early independence. For humans, though, the lack of early visual skills encourages infants to stay close to their caregivers. Experience, Eliot writes, controls the wiring of our visual cortex. The lack of visual stimulus, for example, can hamper later development of hand-to-eye coordination, and problems such as crossed eyes can deprive a child of binocularity. Since we are visually centered animals, a child's visual experience is important in shaping the rest of his mind.

But the most important sense for intellectual development may be hearing because it leads to the development of language. It also strongly influences emotional development. Hearing begins in the womb and is very advanced at birth, so early detection of hearing impairment can avoid detrimental effects to children's language skills.


Emergence of the Mind

The development of emotions, memory and language is dependent on experience as well, as Eliot demonstrates. Success in later life may stem more from children's emotional intelligence than their IQs. Tests for impulse control in four-year-olds are a better predictor of later high school success than the IQ test, for example.

Language has its own apparatus, like an "extra chip" for humans. Humans have two distinct regions that process different aspects of language (verbs and grammar versus nouns and meanings). This shows that language is innate in the human species. All languages share a "Universal Grammar" ( as Noam Chomsky has argued), and it is grammar that sets human language apart from other animal communication.

Although the capacity for language is instinctive, the particular language we each master is a function of experience. Verbal skills of infants and children can thus be improved by conversation.



There are many areas of human intelligence, only one of which is measured by the IQ test. "The logical conclusion," Eliot argues, "is that there is no single type of intelligence, but many different ones, and the concept 'intelligence' becomes a synonym for excellence in any single area."

Brain size isn't everything, either. Intelligence is based on speed, efficiency of use and memory capacity as well. And all factors except brain size can be improved with proper stimulation.

According to many studies, genes contribute about fifty percent towards a human's intelligence as measured by the IQ test. The remainder is environmentally determined. Early experience--proper nutrition, a stimulating environment, and a nurturing parent / caregiver style--is critical to a child's later intellectual potential. As Eliot writes, experience


rewires the brain. Whether early in a baby's life or well into old age, active synapses and pathways continue to be strengthened, and inactive ones weakened, according to the sights, sounds, feelings, and events of daily life. Learning, then, is really just an extension of development, a later manifestation of the remarkable ability of each individual's brain to modify itself according to his or her unique experiences.


What's Going On in There? is a fascinating book, rich in detail and advice. Eliot is particularly good at raising awareness of the dangers as well as the benefits to developing brains. (Not surprisingly, she encourages an active role in upbringing.) Her study has the potential to help all parents and children. Of course, much of the book's market will undoubtedly be well-read parents who are already prepared for informed child rearing, but teachers of young children should also find it useful.

Luckily for such a complicated subject, Eliot's style is straightforward and clear. While she doesn't talk down to her readers, she simplifies enough to enable non-scientific individuals to understand the general concepts, even if they don't memorize the particular terms. Numerous charts and graphs help (as does the index). A glossary would have been a nice addition, but its absence doesn't detract overall.

This should be required reading for anyone interested in realizing their child's potential. Click here to find any book!


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