When does the fetus's brain begin to work?

Generally speaking, the central nervous system (which is composed of the brain/spinal cord) matures in a sequence from "tail" to head. In the 5th week after conception, the first synapses begin forming in a fetus's spinal cord.

By the 6th week, these early neural connections permit the first fetal movements - spontaneous arches & curls of the whole body -that researchers can detect thru ultrasound imaging.

Many other movements soon follow - of the limbs (8 weeks) & fingers (10 weeks), as well as some surprisingly coordinated actions (hiccuping, stretching, yawning, sucking, swallowing, grasping & thumb-sucking).

By the end of the 1st trimester, a fetus's movement repertoire is remarkably rich, even though most pregnant women can feel none of it. (Most women sense the first fetal movements around 18 weeks of pregnancy.)

The 2nd trimester marks the onset of other critical reflexes: continuous breathing movements (that is, rhythmic contractions of the diaphragm & chest muscles) & coordinated sucking & swallowing reflexes.

These abilities are controlled by the brainstem, which sits above the spinal cord but below the higher, more recently-evolved cerebral cortex. The brainstem is responsible for many of our body's most vital functions - heart rate, breathing & blood pressure. It's largely mature by the end of the 2nd trimester, which is when babies first become able to survive outside the womb.

Last of all to mature is the cerebral cortex, which is responsible for most of what we think of as mental life:

• conscious experience
• voluntary actions
• thinking
• remembering 
• feeling

It has only begun to function around the time gestation comes to an end. Premature babies show very basic electrical activity in the primary sensory regions of the cerebral cortex - those areas that perceive touch, vision & hearing - as well as in primary motor regions of the cerebral cortex.

In the last trimester, fetuses are capable of simple forms of learning, like habituating (decreasing their startle response) to a repeated auditory stimulus, such as a loud clap just outside the mother's abdomen.

Late-term fetuses also seem to learn about the sensory qualities of the womb, since several studies have shown that newborn babies respond to familiar odors (such as their own amniotic fluid) & sounds (such as a maternal heartbeat or their own mother's voice).

In spite of these rather sophisticated abilities, babies enter the world with a still-primitive cerebral cortex & it's the gradual maturation of this complex part of the brain that explains much of their emotional & cognitive maturation in the first few years of life.

Postnatal Development

How developed is the brain by birth?

Although it's already undergone an amazing amount of development, the brain of a newborn baby is still very much a work-in-progress. It's small - little more than 1/4 of its adult size & strikingly uneven in its maturity.

By birth, only the lower portions of the nervous system (the spinal cord/brain stem) are very well developed, whereas the higher regions (the limbic system/cerebral cortex) are still rather primitive.

The lower brain is therefore largely in control of a newborn's behavior: all of that kicking, grasping, crying, sleeping, rooting & feeding are functions of the brain stem & spinal cord. Even the striking visual behavior of newborns - their ability to track a bold moving object, like a red ball of string, or to orient to Mom or Dad's face - is thought to be controlled by visual circuits in the brain stem.

When pediatricians conduct a series of reflex tests on the newborn, they're primarily assessing the function of these lower neural centers. These reflexes include the doll's eye maneuver (the baby's eyes stay focused forward when his head is turned to one side), the "Moro" or startle response (baby splays out arms & then slowly closes them in response to a sudden movement or feeling of falling) & even the remarkable stepping reflex (the baby "walks" when you hold him up with feet touching a flat surface).

The human brain takes time to develop, so nature has insured that the neural circuits responsible for the most vital bodily functions - breathing, heartbeat, circulation, sleeping, sucking & swallowing - are up & running by the time a baby emerges from the protective womb.

The rest of brain development can follow at a more leisurely pace, maximizing the opportunity for a baby's experience & environment to shape his emerging mind.

What role do parents play in a baby's brain development?

Parents are another important part of the developmental equation. Infants prefer human stimuli:

• your face
• voice
• touch
• & even smell

over everything else.

They innately orient to people's faces & would rather listen to a speech or singing than any other kind of sound.

Just as newborn babies are born with a set of very useful instincts for surviving & orienting to their new environment, parents are equally programmed to love & respond to our babies' cues. Most adults (& children) find infants irresistible & instinctively want to nurture & protect them.

It's certainly no accident that the affection most parents feel towards their babies & the kind of attention we most want to shower them with:

• touching
• holding
• comforting
• rocking
• singing 
• talking to

provide precisely the best kind of stimulation for their growing brains.

Because brain development is so heavily dependent on early experience, most babies will receive the right kind of nurturing from their earliest days, thru our loving urges & parenting instincts.

In spite of all the recent hype about "making your baby smarter," scientists haven't discovered any special tricks for enhancing the natural wiring phase in children's brain development. Normal, loving, responsive caregiving seems to provide babies with the ideal environment for encouraging their own exploration, which is always the best route to learning.

The one form of stimulation that has been proven to make a difference is language: infants & children who are conversed with, read to & otherwise engaged in lots of verbal interaction show somewhat more advanced linguistic skills than children who aren't as verbally engaged by their caregivers.

Because language is fundamental to most of the rest of cognitive development, this simple action - talking & listening to your child - is one of the best ways to make the most of his or her critical brain -building years.

What are the most important changes in the brain after birth?

While babies come into the world with some very useful survival reflexes, they're still strikingly helpless, because the cerebral cortex is still quite immature. As the highest, most recently evolved part of the brain, the cerebral cortex is responsible for all of our conscious thoughts, feelings, memories & voluntary actions.

Although all of the neurons in the cortex are produced before birth, they're poorly connected. In contrast to the brain stem & spinal cord, the cerebral cortex produces most of its synaptic connections after birth, in a massive burst of synapse formation known as the exuberant period.

At its peak, the cerebral cortex creates an astonishing 2 million new synapses every second. With these new connections come a baby's many mental milestones, such as color vision, a pincer grasp, or a strong attachment to his parents.

By 2 years of age, a toddler's cerebral cortex contains well over a hundred trillion synapses. This period of synaptic exuberance varies in different parts of the cerebral cortex:

 it begins earlier in primary sensory regions, like the visual cortex or primary touch area of the cortex, while it takes off somewhat later in the temporal & frontal lobes, brain areas involved in higher cognitive & emotional functions.

Nonetheless, the number of synapses remains at this peak, over-abundant level in all areas of the cerebral cortex thru-out middle childhood (4-8 years of age).

Beginning in the middle elementary school years & continuing until the end of adolescence, the number of synapses then gradually declines down to adult levels.

This pattern of synaptic production & pruning corresponds remarkably well to children's overall brain activity during development.

Using PET imaging technology, neuroscientists have found dramatic changes in the level of energy use by children's brains over the first several years of life - from very low at birth, to a rapid rise & over-shoot between infancy & the early elementary school years, followed by a gradual decline to adult levels between middle childhood & the end of adolescence.

In other words, children's brains are working very hard, especially during the period of synaptic exuberance that corresponds to the various critical periods in their mental development (see above).

Besides synapse formation & pruning, the other most significant event in postnatal brain development is myelination. Newborns' brains contain very little myelin, the dense impermeable substance that covers the length of mature brain cells & is necessary for clear, efficient electrical transmission.

This lack of myelin is the main reason why babies & young children process information so much more slowly than adults - why it might take a toddler a minute or more to begin responding to a request such as "Joey, bring Mommy the teddy bear."

Myelination of the cerebral cortex begins in the primary motor & sensory areas - regions that receive the first input from the eyes, ears, nose, skin & mouth - & then progresses to "higher-order," or association regions that control the more complex integration of perception, thoughts, memories & feelings.

Myelination is a very extended process: although most areas of the brain begin adding this critical insulation within the first 2 years of life, some of the more complex areas in the frontal & temporal lobes continue the process thru-out childhood & perhaps well into a person's 20's.

Unlike synaptic pruning, myelination appears to be largely "hard-wired." Its sequence is very predictable in all healthy children & the only environmental factor known to influence it is severe malnutrition.

Are there any differences in the development of boys' & girls' brains?

Yes, but they're subtle & a product of both nature & nurture.

Neuroscientists have known for many years that the brains of men & women aren't identical. Men's brains tend to be more lateralized -that is, the 2 hemispheres operate more independently during specific mental tasks like speaking or navigating around one's environment.

For the same kinds of tasks, females tend to use both their cerebral hemispheres more equally.

Another difference is size: males of all ages tend to have slightly larger brains, on average, than females, even after correcting for differences in body size.

Electrical measurements reveal differences in boys' & girls' brain function from the moment of birth. By 3 months of age, boys' & girls' brains respond differently to the sound of human speech.

Because they appear so early in life, such differences are presumably a product of sex-related genes or hormones. We do know that testosterone levels rise in male fetuses as early as 7 weeks of gestation & that testosterone affects the growth & survival of neurons in many parts of the brain.

Female sex hormones may also play a role in shaping brain development, but their function is currently not well understood.

Sex differences in the brain are reflected in the somewhat different developmental timetables of girls & boys. By most measures of sensory & cognitive development, girls are slightly more advanced:

• vision
• hearing
• memory
• smell 
• touch

are all more acute in female than male infants. Girl babies also tend to be somewhat more socially-attuned - responding more readily to human voices or faces, or crying more vigorously in response to another infant's cry & they generally lead boys in the emergence of fine motor & language skills.

Boys eventually catch up in many of these areas. By age 3, they tend to out-perform girls in one cognitive area:

• visual-spatial integration

which is involved in navigation, assembling jigsaw puzzles & certain types of hand-eye coordination.

Males of all ages tend to perform better than females on tasks like mental rotation (imagining how a particular object would look if it were turned 90 degrees) while females of all ages tend to perform better than males at certain verbal tasks & at identifying emotional expression in another person's face.

(It's important to emphasize that these findings describe only the average differences between boys & girls. In fact, the range of abilities within either gender is much greater than the difference between the "average girl" & the "average boy." In other words, there are plenty of boys with excellent verbal skills & girls with excellent visual-spatial ability. While it can be helpful for parents & teachers to understand the different tendencies of the 2 sexes, we shouldn't expect all children to conform to these norms.)

Genes & hormones set the ball rolling, but they don't fully account for sex differences in children's brains. Experience also plays a fundamental role. Consider, i.e., the "typical" boy, with his more advanced spatial skills; he may well prefer activities like climbing or pushing trucks around - all of which further hone his visual-spatial skills.

The "typical" girl, by contrast, may gravitate more toward games with dolls & siblings, which further reinforce her verbal & social skills. It isn't hard to see how initial strengths are magnified - thanks to the remarkable plasticity of young children's brains - into significant differences, even before boys & girls begin preschool.

But this remarkable plasticity also provides parents & other caregivers with a wonderful opportunity to compensate for the different tendencies of boys & girls; i.e., it's known that greater verbal interaction can improve young children's language skills.

So the "typical boy" may especially benefit from a caregiver who engages him in lots of conversation & word play. The "typical girl" may benefit more from a caregiver who engages her in a jigsaw puzzle or building a block tower - activities that encourage her visual-spatial integration.

The point isn't to discourage children from sex-typical play (since pushing trucks or playing w/dolls are great activities for any young child), but to supplement those activities w/experiences that encourage the development of many competences.

Does experience change the actual structure of the brain?

Yes. Brain development is "activity-dependent," meaning that the electrical activity in every circuit:

• sensory
• motor
• emotional
• cognitive

shapes the way that circuit gets put together.

Like computer circuits, neural circuits process information thru the flow of electricity. Unlike computer circuits, however, the circuits in our brains aren't fixed structures.

Every experience - whether it's seeing one's first rainbow, riding a bicycle, reading a book, sharing a joke - excites certain neural circuits & leaves others inactive. Those that are consistently turned on over time will be strengthened, while those that are rarely excited may be dropped away.

Or, as neuroscientists sometimes say, "Cells that fire together, wire together." The elimination of unused neural circuits, also referred to as "pruning," may sound harsh, but it's generally a good thing.

It streamlines children's neural processing, making the remaining circuits work more quickly & efficiently. Without synaptic pruning, children wouldn't be able to walk, talk, or even see properly.

What is a "critical period" in brain development?

Pruning or selection of active neural circuits takes place thru-out life, but is far more common in early childhood. Animal studies have shown there are certain windows of time during which the young are especially sensitive to their environment:

• newborn mice must experience normal whisker sensation in the 1st few days of life or they'll develop abnormal tactile sensitivity in the face region

• cats must be allowed normal visual input during the first 3 months or their vision will be permanently impaired

• monkeys need consistent social contact during the first 6 months or they'll end up extremely emotionally disturbed

Many of the same critical periods appear to hold for human development, although we're less certain about their exact length.

Thus, babies also require normal visual input or they may suffer permanent impairment; children born w/crossed or "lazy" eyes will fail to develop full acuity & depth perception if the problem isn't promptly corrected.

Language skills depend critically on verbal input (or sign language, for babies w/hearing impairments) in the 1st few years or certain skills, particularly grammar & pronunciation, may be permanently impacted.

The critical period for language-learning begins to close around 5 years of age & ends around puberty. This is why individuals who learn a new language after puberty almost always speak it with a foreign accent.

Are there critical periods in the development of every brain function?

Probably not. In the case of visual development, certain abilities are more at-risk than others when a young child's vision is impaired by eye-crossing or other visual problems (i.e., congenital cataracts).

Thus, 2 visual abilities:

• acuity (the perception of fine detail)
• binocularity (the coordinated use of both eyes)

which is especially important for depth perception - do depend on normal visual experience as a child, whereas 2 other visual abilities:

• color 
• peripheral vision 

aren't impaired by visual problems in early life.

A similar distinction holds for language development: certain skills (incl: grammar & phonology - the ability to perceive & produce individual speech sounds) are more sensitive than others (such as vocabulary size) to a child's experience with language in the first few years of life.

We know much less about the development of other mental skills, such as:

• emotional functioning
• mathematical ability
• musical skill

If their development is comparable to vision & language, we may expect that some features will be subject to a critical period while others aren't. One musical skill known as "perfect pitch" - the ability to identify a musical note without reference to a tuning note - seems to develop only in musicians who began their training before the age of 7 (& then, not in all professional musicians).

Similarly, a child's social-emotional development depends on a positive, nurturing attachment to a primary caregiver, based on the higher frequency of serious behavioral problems among children who were severely neglected during the 1st year or more of life, (i.e., the thousands of Romanian children reared in state-run orphanages).

Comparable problems emerge among monkeys who are reared in isolation & neuroscientists are beginning to understand how the lack of attachment in infancy alters development of emotional areas of the primate brain.

When is the brain fully developed?

In some way, never. Our brains are continually re-shaping themselves to meet the demands of everyday life, even throughout adulthood.

However, there are certain aspects of brain structure & function that do level off during development. For example, the number of neurons peaks even before birth; some 100 billion are formed during just the first 5 months of gestation. (Recent evidence suggests that new neurons are produced throughout life, though far less rapidly & probably in numbers sufficient only to replace those that gradually die off.)

In spite of the great number of neurons present at birth, brain size itself increases more gradually: a newborn's brain is only about 1/4 the size of an adult's. It grows to about 80% of adult size by 3 years of age & 90% by age 5.

This growth is largely due to changes in individual neurons, which are structured much like trees. Thus, each brain cell begins as a tiny sapling & only gradually sprouts its hundreds of long, branching dendrites. Brain growth (measured as either weight or volume) is largely due to the growth of these dendrites, which serve as the receiving point for synaptic input from other neurons.

Another way of measuring brain development is to look at the speed of neural processing. A newborn's brain works considerably more slowly than an adult's, transmitting information some 16 times less efficiently.

The speed of neural processing increases dramatically during infancy & childhood, reaching its maximum at about age 15. Most of this increase is due to the gradual myelination of nerve cell axons (the long "wires" that connect one neuron to another neuron's dendrites.)

Myelin is a very dense, fatty substance that insulates axons much like the plastic sheath on a power cable, increasing the speed of electrical transmission & preventing cross-talk between adjacent nerve fibers. Myelination (the coating or covering of axons with myelin) begins around birth & is most rapid in the first 2 years but continues perhaps as late as 30 years of age.

Synaptic development is a more complicated issue. Synapses are the connecting points between the axon of one neuron & the dendrite of another. While information travels down the length of a single neuron as an electrical signal, it's transmitted across the synapse through the release of tiny packets of chemicals or, neurotransmitters.

On the receiving (post-synaptic) side, special receptors for neurotransmitters change the chemical signal into an electrical signal, repeating the process in this next neuron in the chain. The number of synapses in the cerebral cortex peaks within the first few years of life, but then declines by about 1/3 between early childhood & adolescence.

How does nutrition affect the developing brain?

Brain development is most sensitive to a baby's nutrition between mid-gestation & 2 years of age. Children who are malnourished - not just fussy eaters but truly deprived of adequate calories & protein in their diet - thru-out this period don't adequately grow, either physically or mentally.

Their brains are smaller than normal, because of reduced dendritic growth, reduced myelination & the production of fewer glia (supporting cells in the brain which continue to form after birth & are responsible for producing myelin).

Inadequate brain growth explains why children who were malnourished as fetuses & infants suffer often lasting behavioral & cognitive deficits, including slower language & fine motor development, lower IQ & poorer school performance.

A baby's birth weight - & brain size - do depend on the quality of his or her mother's nutrition during pregnancy. Pregnant women should gain about 20% of their ideal pre-pregnancy weight (e.g., 26 pounds for a 130-lb woman) to insure adequate fetal growth.

This requires consuming an extra 300 calories per day, including 10-12 extra grams of protein.

After birth, brain growth depends critically on the quality of a child's nutrition. Breast milk offers the best mix of nutrients for promoting brain growth, provided that breast-fed infants receive some form of iron supplementation beginning around 6 months of age. (Most infant cereals are fortified w/iron & breast-fed babies require this supplementation at 6 months whether or not their mothers are iron-deficient.)

Iron deficiency has been clearly linked to cognitive deficits in young children. Iron is critical for maintaining an adequate number of oxygen-carrying red blood cells, which in turn are necessary to fuel brain growth. Bottle-fed babies should receive formula that contains iron.

Because of the rapid pace of myelination in early life, children need a high level of fat in their diets - some 50% of their total calories - until about 2 years of age. Babies should receive most of this fat from breast milk or formula in the 1st year of life & breastmilk remains an excellent source of liquid nutrition into the toddler years.

However, whole cow's milk can be introduced after the 1st birthday & provides an excellent source of both fat & protein for toddlers in the 2nd year. After 2 years of age, children should begin transitioning to a more heart-healthy level of dietary fat (no more than 30% of total calories), including lower-fat cow's milk (1 or 2%).

how thinking negatively can make you feel better

WHEN YOU'RE ANGRY or in a bad mood or upset, it doesn't work very well to try to be positive. Your whole mind-set is against it.

But you can get out of it with a special kind of negative thinking. It's the key technique of Cognitive Therapy (the most effective therapy available, according to over 600 studies).

Here it is: Criticize your own thinking. Be negative about your own mistaken, exaggerated, distorted thoughts. The fact is, when you're upset, your thinking becomes irrational & your negative (& false) conclusions keep you upset.

Author: Adam Khan

Ask yourself, "How many people could I really tell exactly what I'm thinking?" One? Maybe 2... including your mother & then, most likely, you can't tell her... everything....

This is true for 2 important reasons. First; we're afraid of ridicule. We hate to give someone a tool to mock us with, "Oh, that's so silly," or "How stupid!" These rebukes are harmless enough statements & most often, used in a joking manner, but still, we don't like to hear them.

2nd & more importantly; we're afraid that our true thoughts might frighten them away from us. We're afraid that if they really knew what we were thinking... they wouldn't want to be around us... they wouldn't want to remain our friend... that if they knew how we think, they might not love us anymore.

It isn't that we're thinking so wrongly, or perversely. It's that we have such a jumble of "programmed reactions" & "subconscious suggestions" assaulting us from the media. Every idiotic advertising campaign runs thru our mind each time our mother suggests that we use a certain brand of laundry detergent. We can adequately envision challenging her to once & for all match her personal whites with our personal whites, or we can envision stuffing her into the washing machine... or worse.

We tend to interpret these momentary lapses of reason as insanity. Some of us even get so into thinking in a bizarre manner, that we willingly choose to think abstractly, thus, we can support the notion that we're undeserving, or that we're so bad... or even... insane!

Many of us have even fallen into the habit of stating,

• "I'm so crazy."
• "I'm going nuts."
• "I'm just mad about you."
• "I'm out of my head."
• "I've just been out of control."
• "It just drives me up a wall"
• "My kids are driving me crazy."
• "I feel like a looneytoon."
• "I'm losing my head."
• "I'm delirious."
• "I'm just touched in the head."
• "I'm not in my right mind."
• "I need to come to my senses."
• "That just kills me."
• "If you're not careful, I'll go insane & I'll take you with me...."
  

The only problem with these statements, is... that we come to believe them.

We think them, then we believe them & so we give over our control to admitting that there's some more rational way of analyzing life. If there's a more rational way, then we aren't utilizing that rational power & therefore, we obviously must not be... rational.

Too many of us, were even proud of our wildness... our insanity. We thought that it made us unique, cool... or a free-spirit. It doesn't. If negative thinking is the root of all negative illnesses, such as addiction & nearly everyone is addicted to something, then our seeking to establish our negative "insanity" simply makes us exactly like everyone else.

Actually, we're still supporting our negative self-image by our claiming that we're different... that we're just crazy! We think we're claiming uniqueness when we're really joining the rest of the human race in their own private mental abasements.

These strange associations & thought patterns aren't your fault. We've been programmed this way. The good news is:

we can recognize these strange associations for what they really are & then, properly identify them, so that we may defeat them.

They're just thoughts. Everyone has them, some just more than others, but then some of us watched more TV then others. Having them, doesn't verify our supposed insanity. Since you've had these cartoon-like commercials blasted into your mind, thousands of times, it's only natural for your mind to "free-associate."

When you're walking thru a grocery store, you'll pick the product that was most repetitiously or creatively forced upon your conscious mind. We'll purchase whatever will give us sex-appeal & kissing sweet breath....

Now, that we recognize that our thoughts are our power, we can begin to search out Universal Truths that support this revelation. We will become more sensitive to what makes us react the way that we do. We'll recognize the need to acquire more information on this subject, so we can determine if we need to guard our thinking / programming processes with greater consideration.

With our thoughts, we dictate our emotions. We "feel" what we think we feel. We feel down, if we think we should have a reason to feel down. We feel up if we think we should have a reason to feel up. We don't have to change our feelings. We don't have to overcome depression... or insanity....

We have to overcome our thoughts that lead us to believe that we're ill.

If we change our thoughts, our emotions will follow. If our MINDSET is focussed on "insane," then we'll produce actions that substantiate our claims to insanity. If our MINDSET is focussed on healing, then we'll begin to produce more healing thoughts. We absolutely know, that...

CAN YOU open your mind to a different perspective?

Can you consider that there's an alternative?

Are you capable of allowing your spirit to become receptive?

Are you capable of changing your thoughts?

If you can... if you're capable... then you may receive the gift of the following promises.

PROMISE #1. We can overcome any of our past "feelings," by renaming them & then using them constructively. We can master the ability to see the world thru different eyes. We are in effect, becoming different beings. We will be amazed at what we discover that we can see. We can be different!