Book Notes: WHATS GOING ON IN THERE? LISE ELIOT, Ph.D.

I personally wanted to get a better understanding of infant development. This audible book is 18 hours long. Below are my notes and cliff notes version of the book if you don't have time to sit in on the full 18 hours. Click "Read More" at the bottom of this post to read the notes. 

Lise Eliot, Ph.D is a neuroscientist that explains how the baby's brain is developed from conception to 5 years of life. Lise Eliot is a neurobiologist and assistant professor in the Department of Cell Biology and Anatomy at the Chicago Medical School. She received her Ph.D. in neuroscience from Columbia University and has published work in this field in many professional journals. This is her first book. She lives outside Chicago with her husband and three young children.

Chapter 1 Nature vs. Nurture : A study was done based on families in the prison. Babies from prison families grew up normally because of the attention they got vs. babies that had few attention with being in the crib had issues with social environments. Babies are not born with blank slates, but they are not miniature versions of adult brains. Brain is still growing when born (Cerebellum and Cerebral Cortex). Early nurture / early environment / and hereditary (DNA) vs. experiences.  At birth spinal cord and brain's goal is to survive and grow and both are poorly developed when born. The brain programs itself and access brain cells when needed. Adaptability shaped by environment. Genes and environment play a huge role, but little can be done about genetics. 

Chapter 2 The basic biology of brain development : Fertilization 23 chromosomes from each parent (46 total). 4 days after embryo has divided 5x and resembles a blackberry and clump of 32 cells, only 3-5 cells actually become your child and the outside cells become the placenta. 7 days after fertilization the embryo gets implanted and the cells reshape into a disc with 2 tissue types: Endoderm (inner body) and Ectoderm (outer body). A 3rd type must form before the neuro can form. Mesoderm (all bones and issue to connect everything) which happens day 13, and day 16 the mesoderm connects with the ectoderm to become the babies brain, skin, and nervous system. Neuro starts 19 days and now nature has been set. At day 24, creates a neural tube and at day 26 the tube closes top tube which becomes the brain and the bottom end becomes the spinal cord. 4 weeks after fertilization the brain in formed, heart and eyes are created and now baby is 3mm. Week 5 brain subdivides into a 5 ventricle system. Week 6 brain differentiates into all major structures, 12 cranial nerves have created but not connected (Nose, Face, Ears, and Eyes). Week 7 is typically first OBGYN appointment (9 weeks pregnant), Doctors  count from first day of last period, book is based on fetal development and is based on conception date. Week 8, now is 2 inches and it considered a fetus, organs not fully formed no more tail (spina bifida - tube isn't closed). Baby now has fingers and toes.
The Fetus Brain:  Week 9 the brain is still forming basic shape and takes longer than other developments. The spinal cord function controls the fetal movements. End of the 1st trimester, Week 13, morning sickness protects baby brain, 5 inches long, the cerebral cortex is undifferentiated and smooth. Week 16, OBGYN appointment ultrasound shows baby is 8 inches, fingers and toes, central nervous system, 4 beating chambers in the heart, and gender of baby. Week 24, 14 inches long, cerebral cortex still not functional, breathing movements. the cerebral cortex will continue to grow after birth but the brain in general changes very little. The birth and growth of neurons: the human brain is built out of millions of neurons.  A young child's environment (feels, thinks, tastes, ect.) is a direct influence on the structure of their brain. 

Chapter 3 Prenatal Influences of the Developing Brain : The womb is a quiet, warm, dark, and a safe place that makes perfect for an environment for brain development. Babies born 8 or more weeks early remain at high risk for many mental and neurological problems including visual, hearing, motor deficits, attention problems and language delays. Fatigue and morning sickness  in early pregnancy sets in during the most vulnerable developing stage to prevent over exertion and risky physical activities and keeping the diet bland to avoid toxins in spoiled or exotic foods. These symptoms are typically featured in the placental hormone called HCG, which can be detected after 1 week from gestation, and its levels peak at 10 weeks (8 weeks past gestation). Although the womb is a safe place, exposure to medications, toxins, and chemicals can still pass though the placenta, this usually only accounts for 10% known birth defects. Estimate 60% of birth defects are not identified with any identifiable causes and occur spontaneously. 20 -25% birth defects are genetic.
Neural Tube Defects (NTD): The neural tube must close 22- 28 days after conception, failure to close is called spinal bifida, and can range to different severities. NTD is a common cause in spontaneous miscarriages and more prevalent in different ethnic groups and geographical locations (Rates are high in UK, low in Finland / high in U.S. East Coast, low in West Coast/ African American Ethnicity is low / Native American is high). Elevated temperature during pregnancy (hot tub, sauna, fever), has caused NTD. NTD can be tested early in the second trimester with ultrasound technology and amniocentesis measuring the AFP (alpha-fetoprotein). AFP is created by the fetus and normally present in low concentration in the brain and spinal cord,  if the neural tube did not close, AFP can cross into the amniotic fluid into the placenta and into the mothers blood so if there is AFP in the mothers blood or amniotic fluid it is suggest that the fetus has a NTD. The blood test is best to take 16-18 weeks of pregnancy because this is the time where detecting an abnormal AFP is the highest. There is a risk of the test getting a false positive if the fetus is further along or if multiple fetuses are present. 93% of all NTD can be detected before the first half of pregnancy. Women who take B vitamin Folate or Folic Acid  during conception and during the first few weeks of pregnancy are substantially less likely to have NTD. Nearly half of all pregnancies in the US are not planned and because the neural tube closes so early in the development process many women won't be taking the vitamin b/ folate or folic acid around the time is actually needed. 
Effects of Nutrition on the Developing Brain: From midway through gestation and to 2 years after birth the brain is highly sensitive to the quantity and quality of the nutrition baby receives. A mothers diet can shape the baby's brain development. Undernourished fetuses or children can have permanent brain function impairment. Malnourished children tend to score lower in IQ tests, perform more poorly in school, slower language development, exhibit more behavioral problems, and have difficulty with sensory integration of motor skills. Malnourished infants usually grow up in less stimulating and supportive environments. Over the counter medicines should be avoided unless the mother is extremely uncomfortable. Tylenol is the recommend pain reliever as aspirin can cause brain hemorrhage. 
Illegal Drugs / Chemicals / Radiation : Alcohol, Cigarettes, Illegal Drugs, Caffeine, Aspartame, and Monosodium Glutamate; Ionizing Radiation, Non ionizing Radiation, Non ionizing Electromagnetic Radiation, Microwaves and Radio Waves, VDT’s, MRI’s, and Ultrasound. Maternal Infections : Rubella, Cytomegalovirus, Toxoplasmosis, Genital Herpes, Chicken Pox, Syphilis. Influenza : Maternal flu infections can have severe affects to the fetus brain and scientists believe there is a link between the flu during pregnancy raises the risk for NTD, Schizophrenia, and Dyslexia.  Maternal Hormones : Melatonin can alter brain development during mid gestation. Maternal Emotion & Stress : The bodies response to stress is fight or flight and release adrenaline, the mothers stress hormone is passed through the placenta. If hormone levels get to high, or highly anxious mothers can overdose their fetuses with corticosteroids and catecholamines. Extreme maternal stress is also linked to malformations such as cleft lip, down syndrome, neurological impairment, eczema, respiratory difficulty, stomach ulcers, ear infections, and neonatal death. Studies have also tied stress to miscarriages, low birth weight and premature birth. Exercise releases catecholamines and the fetus responds well with light or moderate maternal exercise. Exercise lowers the hormone cortisol and increases the mothers sense of well being. Women who exercise during pregnancy have easier child birthing experience, average 27 minutes pushing than women who do not exercise average 58 minutes.

Chapter 4 How Birth Affects the Brain : Labor and childbirth, baby experiences the most traumatic experience a human ever goes through, hours of crushing contractions through a birth canal smaller than the diameter of the baby's head, reshapes the head , distorting the shoulders, and squeezes the liquid out of the lungs. A lot of things can go wrong in the the labor process such as breach delivery.  Lack of oxygen from the baby brain, but baby brains can tolerate brief periods of oxygen deprivation better than adult brains can, but prolonged lack of oxygen can cause permanent damage. Studies in primates determines that is the baby's brain which makes the ultimate decision of when its time for the baby to be born. 
Benefits of Birth : Birth stress results in elevated catecholamine hormones; during the birth process the baby's heart rate decreases, the breathing slows down, and activity is nearly  paralyzed to conserve energy and blood flow to the most important tissues, such as the brain and the heart.  Catecholamines prepare infant for life outside the womb and these hormones are still raised until the baby is two hours old. Babies born c section do not experience the same catecholamine hormone surge as vaginal delivered babies.  Hospitals can postpone routine medical care to promote parent/infant bonding during the newborns first hour of life. Skin to skin with both parents is important as baby senses through sight and scent. 
Dangers of Birth for Baby's Brain : Of all the organs in the body, the brain is the most sensitive during the birth process but it also very resilient. Swelling of the head can occur, 1-2% of births but more common with the use of vacuum and  forceps. Injuries can occur when the baby is large. Facial damage can occur, 8/1000, paralysis is usually only temporary and nerves can regenerate.
Rare events: Brain tear and bleeding can cause death, cerebral palsy, or mental retardation. Spinal cord damage and can result to death or varying degrees of paralysis, most common in breach. Breach babies are typically delivered via c section to avoid these dangers. Fetal Monitoring does not improve the chances of babies being born healthy. 
Childbirth Choices : The safest way to deliver breach babies is through c section. Manually turning the baby (ECV) in weeks before term is performed under ultrasound to avoid c section. Forceps used during birth is linked to higher trauma during birth. Anesthetics & analgesics are drugs used for pain delivery during birth delivery. Anesthetics can slow the babies brain metabolism. Epidural block is inserted by an anesthesiologist and this procedure is very common in first time births. Although doctors and hospitals say this method is relatively save, a small amount of the drugs used are still transferred from the mothers blood stream to the placenta and to the circulation of the  baby. Two thirds of the mother's concentration of fentanyl can cross over, whereas bupivacaine is about 30%. Studies has been inconclusive if epidural drugs have any effect to baby's brain and the drugs does not stay in the babies system for more than 1-2 days. The most common side effect of epidural in the mother is hypotension, a reduction in blood pressure, if the blood pressure falls too low for too long it compromises the blood flow to the placenta. Many studies have shown that women who receive epidurals have longer labors on average because it relaxes the pelvic muscles. Overall, the effects of epidurals are subtle and no studies have shown any permanent effects. General anesthesia is only exclusively received for c section. Babies born under general anesthesia tend to be less active and alert than babies born vaginally and have more difficulty breastfeeding. 

Chapter 5 The Importance of Touch : Somatosensory system is most developed at birth. Four types of touch: Temperature; Pain; Cutaneous sensation; Proprioception begins in the skin. Each modality feels different because the signals travel along different paths. Ability to feel lies in somatosensory cortex on either side of brain. A fetus has full sensory of touch at 12 weeks. At 10 weeks, babies can determine objects with their hands and at 6 months can perceive different textures. By age 2, babies can identify objects better with their left hand than their right.
Babies can feel pain but will have infantile amnesia. Amniocentesis is not painful to the baby unless accidentally poked. Holding, swaddling, jiggling, gentle stroking, and rocking are all effective ways of reducing baby's reaction to pain perception. Babies cannot regulate their temperature which is why babies wake up more easier to move round in a cold environment and sleep more in a warm environment. Benefits of early touch is essential to sensory motor development, physical growth, emotional well-being, cognitive potential and overall health.  Premature babies are benefited by massage therapy. Full term babies also benefit from regular massage, children show lower anxiety and stress, better mood, and improved sleep patterns when treated when massage. Babies that are held in slings and close to touch don't cry as much.  Touch is one of the easiest ways of molding emotional and mental well-being. 
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Chapter 6 ​Why Babies Love to be Bounced : The Precocious Sense of Balance and Motion : Babies find great comfort in the feeling of repetitive motion. Babies are born with a highly developed Vestibular System which is named for a hollow opening in skull. Involved in the stabilization of gaze and in the control of balance. Composed of 3 semicircular canals, which are filled with fluid and senses rotational movement, and 2 otoliths that senses linear movements, head tilts, and body's position in relative to gravity. 

In general, the vestibular system operates below the level of consciousness. Prenatal Vulnerability and Development : Certain drugs (amino glycosides) damage hair cells in vestibular and auditory pathway. Defect in the vestibular system have a greater chance of being born in breech position. Vestibular system can be tested by assessing reflex responses: Moro, asymmetrical neck, traction, doll’s eye. The vestibular system isn't fully developed until 7 years of age. Benefits of vestibular stimulation contributes to development of reflexes and motor skills. In the short-term, it soothes and comforts infants, continued stimulation decreases infants arousal.

Chapter 7 The Early World of Smell : Smell, taste and touch are well developed senses at birth. Smell and taste have “Chemical” senses in which neural excitation in response to molecules in environment.  Babies are able to small colostrum after birth, information is transmitted directly from nose to cerebral cortex – no information processing through lower brain centers. Babies rely on smell in infancy more than at any other time. ​Development of Olfactory System starts at  5 weeks gestation creating a Nasal pit. At 7 weeks, Nostrils develop. Olfactory epithelial cells develop and are continuously generated throughout life. At 8 weeks the Olfactory bulb forms. At 13 weeks the Bulb is walled off with thin bone layer. At 28-weeks, the fetus has the ability to smell. While smell developed early on, the experience still important. Smell is not impeded by amniotic fluid. Throughout the third trimester, fetuses can smell odor. Amniotic odors are appealing, comforting and important. Mother’s Breast: Washed vs. unwashed; Nursing vs. non-nursing; Bottle-fed vs. breast-fed; Calming effect of mother’s scent. Babies prefer scent of own mother or caretaker. Nursing babies: richest olfactory experience. After breast, babies prefer the scent of the neck, underarm odor over the scent of a lactating stranger. Bottle-fed babies don't recognize the mothers scent after two weeks of age while breastfeeding babies don't recognize the fathers scent. Don't switch soaps, deodorant, or perfume. Female babies are more sensitive to smell than male babies. At age 6 - 7 their Olfactory preferences are comparable to adults. Scent-marking as develop independence “comfort of Mommy but in a way that they can control”. 

Chapter 8 ​Taste, Milk, and the Origins of Food Preference : Along with touch & smell (vestibular senses), the ability to taste emerges early in development. The sense of taste (gustation) first becomes functional during the third trimester. Taste ability changes slightly during infancy, but taste preference is highly malleable. Like smell, taste is a chemical sense. Taste buds detect only 4 basic categories: sweet; salty; bitter; sour. To taste full flavor then involves considerable interaction between taste and the sense of smell. Taste receptor cells (special elongated epithelial cells that line the pore of each pit like bud). Taste buds are distributed mostly over the perimeter of the tongue (about 4,500 altogether on the tip, sides, back and roof (soft palate) of the mouth, as well as the upper throat. Each taste bud contains some 40 taste receptor cells. Taste buds emerge just 8 wks after conception. By 13 weeks, taste buds have formed throughout the mouth and are already communicating with their invading nerves. The number of taste buds continues to increase for some time postnatally. Evidence shows that babies can taste even before birth and are sensitive to different chemicals in the amniotic fluid. Fetuses can taste some flavors (sweet and perhaps bitter) by the last 2 months of gestation. Taste buds mature at the very end of the first trimester. Amniotic fluid is rich with chemicals that excite taste cells and the amniotic fluid is constantly changing over the course of pregnancy (through mother’s diet & even the fetus’s own urine). Like prenatal smell, a fetus’s taste experience in the womb may bias of food preferences. Newborns can discern many different flavor, but care only for the taste of sweet. Newborns can even tell the difference between different types of sugar and concentrations of the same type of sugar. Favorite type of sugar is sucrose (table sugar), and it is preferred over fructose (found in fruit). Newborns have built in opinions about sweet, bitter & sour. However, they are indifferent to salt. Although they can detect salt, they neither like nor dislike the flavor. ​Because taste perception is intimately interrelated to touch perception in the area of the mouth and tongue, taste pathways may form their cortical connections as early as the precocious touch system, allowing early conscious awareness of taste. Babies taste abilities continue to evolve during early childhood – the biggest changes are in the perception of salt (usually around 4 months). The delay in development of salt sensitivity is thought to be related to the development of the kidney. The response to salty solutions again changes after 2 yrs of age. Children’s perception of bitterness also evolves. While taste perception is well developed in infancy, the understanding of what is edible is largely learned. The bottom line – Sweets taste good because it literally feels good to eat them – they induce pleasurable sensations in the body. In addition to its calming effects, sugar is known to make babies more alert and to encourage their hand-to-mouth coordination. The many pleasures of nursing: Milk not only contains sugar, but high levels of fat (which has many of the same calming effects as sweets). Fats, too, trigger the release of endogenous opiates, as well as a hormone from the gut called cholecystokinin). The calming effect of sugar and fats, produced by endogenous opiates, promotes growth and development by helping the baby conserve energy and allowing them to concentrate on learning about their environment. Breast milk contains not only nutrients, vitamins and minerals – it contains enzymes, immune factors, hormones, growth factors, and many other agents not yet identified. Breast milk provides the baby with a large array of antibodies, enzymes and even whole immune cells (machrophages, neutrophils, T-cells, & B-cells) that protect them from most of the infections which the mother has even been exposed. In many studies, breast-fed children have been found to be smarter than bottle-fed children. The brain undergoes enormous growth between the 3rd trimester of gestation until at least 18 months of age. All of that massive myelination and synaptic reorganization may be facilitated by specific nutrients: Taurine; Lipids; Non-nutrient Components of Breast Milk.  No two women’s milk is identical, nor any one mother’s milk constant at all times. Variation in breast milk flavors may play an important role in taste development itself. Alcohol passes freely through a mother’s blood into her milk and can be detected in her milk after about 30 minutes and peaks at one hour post-ingestion. By 3 hrs. it is nearly gone, although levels remain elevated longer if she consumes more than 1 drink. Alcohol tends to make milk smell sweeter. Babies sleep less following alcohol ingestion. Babies score lower on motor skills test at 1 yr. of age; however motor development scores do not seem to be affected by maternal drinking. Does Early Taste Experience Influence Later Preferences? Taste preferences are remarkably malleable. Aside from liking sweet and salt, virtually every other aspect of food preference appears to be a product of experience (an acquired taste). Little Brains, Big Taste: Taste is important for children’s emotional development. Certain foods (sweets & fats) literally have mood altering effects that can calm a baby, improve their attention span, and eventually help them sleep. Familiar flavors in mother’s milk provide a comforting bridge between the womb and the outside world and begin to shape a baby’s later food preferences. 
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Chapter 9 Wiring up the Visual Brain : During Brain Development the Sense of Vision is Primitive at Birth. At Six Months, all Primary Visual Abilities will have emerged. Infant’s peripheral vision is first to develop. At One Year Visual Abilities Fully Developed— Nearly as good as an Adult’s. 

Getting the Wiring Right : „Role of Nature shows First Phase of Development Controlled by Genes. Role of Experience is In the Act of Seeing, Synaptic Pruning-Survival of the Fittest or “most active connections”, and During the pruning period---until Age 2. 

What happens if something goes wrong? Up to 5% of Children are born with or will develop visual abnormality. Congenital Cataract – Easily Detectable. Strabismus (Cross-eyed) affects Binocular Vision and can degrade fine acuity but usually shows up in 2-4 months after birth. 

Chapter 10 How Hearing is Involved : The auditory system receive sound waves that translate into electrical signals. The system discriminates different signals into familiar sounds. The auditory system consists of the ear, auditory nerve, brain stem, and cerebral cortex. The ear is divided into three sections: The outer ear contains flap funnels sound into canal. Sound vibrates the ear drum; The middle ear are made up of 3 bones (malleus, incus, stapes) and amplify vibrations; The inner ear, cochlea converts vibrations into electrical signal. Sound impulses travel; sequentially through brain-stem, midbrain, thalamus, to cerebral cortex; primary auditory region – upper ridge of temporal lobe; information from two ears not segregated; and Compared/combined with input from opposite ear in brain-stem. What Can a Fetus Hear? Most fetuses begin hearing by early in the six the month of gestation. Low-frequency sounds cross mother’s abdomen better than high-frequency. Every reasonably loud sound may influence auditory brain development. Mother’s voice loudest to fetus.  Older fetuses can discriminate different speech sounds. Fetuses can remember what they fear – become familiar with environment. What newborns can hear: Insensitive to quiet sounds. Discriminate low frequencies better than high ones. Sound localization – horizontal plane. Sensitive to overall melody or intonation of spoken language (show preference for native tongue). How hearing improves. Frequency Sensitivity by the sixth month can perceive high frequency better than low frequency and are able to distinguish full range of frequencies. How Hearing Improves: Sound Localization, Both horizontal and vertical planes by sixth month and continues to improve gradually until about age 7.  Threshold of overall hearing sensitivity matures slowly and gradually improves until puberty. Temporal Resolution: Gradual improvement in ability to discriminate sounds in time. Six month infant requires duration twice as long as adult to distinguish sound. Discriminating Sounds in a Noisy Background : Ability to mask background noise improves over first two years and Fully mature at about age 10. Hearing Impairment : Congenital hearing loss : Any impairment caused either before or shortly after birth 1/1000 babies born deaf. Up to 3% of all children have some minor form of permanent hearing impairment. Prenatal infections : Rubella virus (German Measles) attacks both inner and middle portions of developing ear. Fetuses infected during first half of gestation likely to be severely hearing impaired. Deafness tends to be severe – may have delayed onset. Prenatal Infections : CMV (cytomegalovirus) : 12% of congenital deafness due to mother’s infection – virus can become reactivated and passed on to fetus. Toxoplasmosis, Genital herpes, and syphilis have also been known to cause hearing loss in unborn children. More than 100 different Drugs and Chemicals are known to specifically damage developing auditory system. Medicines – certain antibiotics, anticonvulsants, diuretics, antithyroid. Recreational – tobacco, alcohol. Environmental – mercury, lead.  Middle Ear Infections. Otitis media (OM) more common than congenital deafness. 80% children will have at least one bout before age of three. Generally doesn’t produce any long-term hearing deficits. ​Because language is the primary means we use to teach our children, hearing is probably the most important sense for their intellectual growth.

Chapter 11 Motor Milestones : 

The Brain has 3 Main Parts that are involved in movement: 

• Cerebral cortex
  • movement commands are initiated, there are three motor areas all located in the back half of the frontal lobes.
  • neurons in the “proper” region of the motor cortex send action potentials directly down to the spinal cord through an important pathway known as the corticospinal tract.
  • primary motor cortex—directly triggers voluntary movements e.g. leg, trunk, arm, hand, face, lips, tongue 
  • supplemental motor area and pre-motor cortex—planning and executing more complex sequences of movement e.g. head and face (supplemental motor area) and legs and feet (pre-motor cortex)
• Cerebellum 
  • keeps movements coordinated & precisely timed 
  • sits in the back of the brain, underneath the cerebral cortex and behind the brain stem 
  • receives input from both the motor cortex (telling what kind of movement is being attempted) & various senses (vision, hearing, balance, & proprioception-telling it what kind of movement is actually taking place)
• Basal Ganglia 
  • includes several distinct clusters, or nuclei, of subcortical neurons 
  • located deep inside the brain - under the lobes of the cerebral cortex, atop the brain stem, and adjacent to the thalamus 
  • plays a critical role in producing movements
  • people with basal ganglia disorders have great difficulty initiating voluntary movements 
  • exerts important control over which motor actions are carried out, suppressing involuntary types

Motor Development  : Neuromuscular maturation, fixed process of skill acquisition (first part of this century) Proven Studies1930-identical twins 1940-Hopi Indian babies. Corticospinal Tract—only in mammals; largest corticospinal tract in humans. Babinski sign— 4-6 months of life (baby’s toes will flare or extend up with stroke at the bottom). After 6 months (baby’s toes will curl downward)— if the babinski sign (toes flaring up) persists beyond about six months of age, it is evidence of a possible neurological delay. Role of the Environment : pace of sensory development; physical growth; strength; nutrition; motivation; emotional; well-being; daily practice.

Chapter 12 Social / Emotional Growth : The development of emotional abilities establishes the foundation from which every other mental skill can flourish. The limbic system is a large set of neural structures that control our social and emotional lives and it is molded by both nature and nurture. The limbic system takes a child’s temperament, the inborn “emotional makeup” which is then influenced by experiences with the environment to form our personality. It sits between the cerebral cortex and the brain stem. The limbic cortex is upper level of the limbic system which modifies and controls our emotional responses. The limbic cortex is where we “consciously feel” our emotions. Two amygdala sit between the cortex and the stem, one in each hemisphere, both serving as the gatekeepers that generate emotions. 
The Emotional Brain : While the left hemisphere of our brain is the more analytical part, the right hemisphere is where we appreciate emotions associated with experiences affecting the left hemisphere. The left part of the medial frontal cortex is where we feel good and the right part is where we feel bad. The limbic system develops from bottom to top with the amygdala formed by the end of gestation. The limbic system also plays an important role in memory storage. The 1st 6 months of development are dominated by the lower limbic system - primarily to help meet the baby’s physical needs. At 6 weeks of age a baby begins to smile at other people - actually having started to smile spontaneously since 30 weeks of gestation. Communicating is the next milestone in social development - with prespeech and protoconversation usually starting at about 6 weeks. At 6 months the higher limbic centers begin to activate - with babies becoming more emotionally responsive and connected with their surroundings. They genuinely begin to feel their emotions. The most important social/emotional development in infancy is the emergence of attachment - a baby’s strong tie to a primary caregiver and the corresponding caregiver’s connection to the baby. Attachment becomes a child’s primary source of security, self-esteem, Self-control and social skills. 
Nonmaternal Care, Stress, Gender, Temperament, and Personality : Most babies manage to bond with mothers regardless of mom’s employment status as long as the mother or caregiver is attentive, responsive, consistent and a stable figure in the child’s life. High quality child care can ensure a child’s emotional health, improve social competence and advance cognitive development. Elevated stress hormones can be hazardous to a healthy limbic system. Emotional differences between boys are girls are innate- girls respond earlier to social stimuli while boys are actually more emotional. Temperament is innate and connected to neurobiology. It is often reinforced by parental responses. Temperament is determined by heredity while about 50% of personality is shaped by experiences - the most important ‘limbic tutors” are a child’s parents. Early experiences of abuse “scar” a child’s limbic system - they can wire susceptibility to aggression, fear, and pain. ​

Chapter 13 The Emergence of Memory : Memory is not a single entity but a patchwork of several different forms of information storage. Infantile Amnesia - cannot remember events from the earliest years of life. Memories then grow longer and increasingly conscious throughout the preschool years until elementary school years. Short-Term Memory - Used for immediate and ongoing applications. Long-Term Memory - refers to any kind of recall outside an immediate timeframe and can be recalled at any time. Explicit Memory - Conscious recollections, who we are and what we know. Implicit Memory - Knowledge of how to do things. Memory is governed by the hippocampus that lies immediately behind the amygdala.  Three other brain regions involved in long-term memory - medial thalamus, basal forebrain, and prefrontal cortex. The entire nervous system participates because information storage is a fundamental property of neurons. The Emergence of Recall - Starts at eight months and beyond and is by definition conscious. Deferred Imitation - Demonstrate a sequence of events to a young child and test whether they reproduce the sequence. Could explain why children are prone to replicating their parents behavior. 

Chapter 14 ​Language and the Developing Brain : Language is hard-wired to the brain. Grammar is what sets our language apart from other animal communication. The particular language a child masters, and the way he ends up speaking it, are largely a function of experience. Early language immersion and practice is necessary for mastering any tongue at all. 
​How Language Works : Left hemisphere – more verbal side. We literally speak with half a brain. The dominant location of language for more than 95% of people, including a sizable majority of left-handers. Right hemisphere – responsible for the inflection and overall musical quality that lend important emphasis to verbal communication. 

The Critical Period for Language Experience : Language development is a simple product of brain maturation, of the different schedules for hooking up Wernicke’s and Boca’s areas and greasing the wires between them. Just like each of the sensory and motor skills on which it depends, language development is also critically shaped by experience.
Language in a Newborn : Language in the first eighteen months. Parenting style affects language learning. Providing early language enrichment. 

Chapter 15 ​How Intelligence Grows in the Brain : Intelligence Facts : There is no single “intelligence center” in the brain. Intelligence is difficult to measure. Most IQ tests measure verbal and performance abilities, but do not measure other type of intelligence (e.g., creativity or musical skills). Multiple Intelligence: verbal, spatial, mathematical-scientific, musical, bodily kinesthetic, self- and social-understanding. Babies are born with brains ¼ the size of adult brains. The brain triples in size the first year. Baby IQ tests do not reliably predict adult intelligence. Why some people are smart and others aren’t? Not because of head/brain size (there is a slight correlation, however). High IQ people react faster to various tasks and process information more efficiently. They have better neural conduction of stimuli. They burn less glucose while performing mental tasks (children’s brains burn more energy than adult brains regardless of IQ). 
Baby Milestone Timeline:
Four weeks: babies can store mental representations of objects 
Four months: babies can categorize objects by shape/color 
Eight months: frontal lobes “turn on” increasing sense of time, inhibition, and attention skills  Eighteen months: language and a sense of self develop 
​Three-Four years: discovery of the mind

Chapter 16 Nature, Nurture, and Sex Differences : Intelligence varies between children : Genetic draw has faster neural transmission, product of experience, maternal encouragement of attention. Environment has more attributable to environmental factors in early infancy than at any later time in life. 
Role of Genes : Behavioral Genetics: Compare IQ of known genetic relationships to calculate the degree to which intelligence is hereditary. Identical twins IQ score .86; Siblings  .47; Parent/Child -score .42 (avg. both parents .72). Consensus - genes account for 40% to 50% of one’s IQ.
The Role of Environment : Head Start Program - Increase in IQ „ Disadvantaged children can benefit; Adoption Studies - Increase IQ Low-socioeconomic children adopted by high socioeconomic parents; “Flynn Effect”- FACT: We are getting smarter : Nutrition, Health, Education, Parenting Skill. Greater in Visual- Spatial (Visual Media). 
Sex Differences in Intelligence :  Brain Development Differences : Males have larger brain ( 8%) than female. Males have larger right brain where spatial information is processed, but women are better organized. Nurture - Play styles : Boys & Trucks /  Girls & Dolls.  Hormones such as Estrogen and Testosterone affect the way males and females think. Estrogen promotes mental skills „ and Testosterone promotes better spatial skills.  Experience and Socialization.