Brain Development  Largest, most developed part at birth  Weight compared to adult brain 25% at birth 75% at age 2 90% at age 5  Normal experience, stimulation, result in normal brain development

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 Dendrites  Cell Body  Axon  Synapse  Neurotransmitters Dendrites Cell Body Axon Synapse Neurotransmitters Dendrites Cell Body Axon Synapse Neurotransmitters Dendrites Cell Body Axon Synapse Neurotransmitters Dendrites Cell Body Axon Synapse Neurotransmitters

 Figure 5-2

Responsiveness to experiences  Can be negative Vulnerable to damage Environmental deprivation  Can be positive Aids in recovery from injury Can compensate for each other Can benefit from stimulation Allows for adaptability

Critical period: Late prenatal & early infancy Lateralization (at birth)  Left hemisphere Analytic reasoning, language  Right hemisphere Understanding spatial information Visual-motor information  Corpus callosum connects the two

Never truly complete  Changes occur across lifespan Growth spurts in infancy, childhood and adolescence Full adult weight by about age 16 Processing speed increases in adolescence Myelination continues into early adulthood

The Aging Brain  Gradual and mild degeneration Elderly adults  5-30% fewer neurons than younger adult  Greater loss in sensory-motor areas  Plasticity still possible Main result of age is slower processing

The top image shows a normal brain, facing left. The brain tissue occupies most of the space available inside the skull. The creases separating the cortical gyri (those sausage-like outer layers of the brain) are narrow, except for one crease running from lower left toward the middle of the image. That separates the temporal lobe from the rest of the brain. The brain below shows the changes with Alzheimer's disease. The cortical gyri have atrophied. Were you to look under a microscope, you'd see a dearth of grey cells. Were you to weigh the brain, it would be significantly lighter.

Procession of growth is orderly  Cephalocaudal: From head, downward  Proximodistal: From the center, outwards  Orthogenic: From global, undifferentiated to specialized

Typically 7 to 7½ lbs., 20 inches long Period of rapid growth Neonatal reflexes  Survival reflexes: Clearly adaptive Breathing, eye-blink, sucking/rooting  Primitive reflexes: Less adaptive Typically disappear by 4 months Babinski: Toes fan, grasping  Used diagnostically

Behavioral States  Short sleep-wake cycles at first  Establish more regularity at 3-6 months  REM sleep 50% of the time for newborns 25-30% by 6 months  May be useful for reducing stimulation  Individuality in infant patterns

Strengths and weaknesses  Sensory system intact  Ability to learn from experience and from consequences  Limited in capacity to move voluntarily  Intentionality also limited  Cannot interpret complex stimuli

Developmental norms (see Table 5.4)  Average age of mastery Gross before fine motor skills Crawling at 7–10 months Walking at about 1 year Study of “walkers” (Siegel & Burton, 1999)  Infants not using walkers sat up, crawled, and walked earlier  Need sensory feedback to see feet

Manipulating Objects  Grasping reflex disappears: 2-4 mo  Pincer grasp by 6 months Motor Skills  Rhythmic Stereotypies Rocking, bouncing, mouthing objects, banging arms and legs Precede a skill then disappear

Age 2 until puberty  2-3 inches in height, 5-6 lbs weight/per year  Bones grow and harden  Run faster, jump higher, and throw a ball farther  Skills very responsive to practice  Hand-eye coordination, fine motor, and reaction time all improve

Education level of parents a factor Nutrition: Well-balanced diet important  High-carb foods detrimental  Child obesity: Junk-food, TV Injuries, auto crashes: Leading cause of death Exercise: Promotes physical, cognitive, social well-being, academic skill

Growth spurt triggered by hormones  Peak in height: Age 12/girls, 14/boys Menarche: Average age 12½ Earlier in countries with good nutrition Maturation different by ethnicity Semenarche: Average age 13 Emission of seminal fluid

Genes set the process in motion Hormones responsible for changes Environment also important  Secular trend: Better nutrition Earlier maturation, larger body size  Poorly nourished mature later  Heavy and tall mature earlier  Regular strenuous exercise mature later

Sequence of Events in the Sexual Maturation of Males and females.

Girls become concerned w/appearance  Individual reactions vary widely  Negative views about menstruation  Ornamental view Boys likely to welcome the changes  Instrumental View Family relations remain important  Distance and conflict with parents Usually about only minor issues

Early males: Advantageous  More positive reactions from others Late/males: Disadvantageous  More behavior and adjustment problems Early/females: Disadvantageous  Subject of ridicule, lower self esteem  Older peer group = problems Late/ females: Academic advantages Differences tend to fade with time

Dramatic physical growth overall Boys continue to improve Girls tend to level off or decline  Not totally explained by biology Gender role socialization important Gender performance gap has narrowed

Obesity a continuing problem  Higher risk: Diabetes, heart, BP problems  Poor eating habits, sedentary lifestyle Leading causes of death  Motor vehicles and violence Alcohol and drug use, cigarette smoking  Also result in risky choices

Minor changes in the 20s & 30s Noticeable by the 40s  Wrinkles, gray hair, weight gain In the 60s: Weight, muscle, bone loss  Osteoporosis in older women Fair, light frame, smokers Calcium, exercise,  Osteoarthritis: Joint deterioration

Most systems show decline with age  Heart and lung capacity  Temperature control  Immune system and strength  Reserve capacity On average, older people are less fit than younger BUT not all Physically active remain fit

Beginning in adolescence  Sex hormones influence behavior Male testosterone Levels fluctuate daily Female estrogen & progesterone Monthly cycle PMS? Expectations vs. hormones Calcium & Vitamin D helpful

Menopause: Estrogen production declines  Age range  Symptoms: hot flashes, vaginal dryness  Little anxiety, irritability, depression, or other stereotypes  Exercise and adequate sleep helpful Andropause: Decreasing testosterone  Symptoms: Changes in Libido, fatigue, erectile dysfunction, and memory problems

Balance difficulty affects the ability to walk, stand, sit, and turn Older people with strong muscles and good cardiovascular capacity can walk briskly Major change is slowing of the CNS  Increased RT  Novel/complex tasks more difficult Physically-fit older people have quicker RT

Birren (1963) study of men aged  Healthy older same as younger  Conclusion: Aging itself has little effect on physical and psychological functioning Disuse: “Use it or lose it!”  Includes mental exercise Abuse contributes to decline  Alcohol, high-fat diet, smoking

Acute illnesses less common Chronic disease more common Most 70-yr-olds: At least 1 chronic impairment Tremendous variability Exercise, nutrition: Lifelong benefits  Improves cardio, respiratory functioning  Slows bone loss, strengthens muscles  Less depression, delays disability

Osteoporosis: Smokers, light frame, at risk  Increase calcium  Weight-bearing exercise Osteoarthritis: deterioration of cartilage Successful aging  Both physical and mental functioning  Positive attitude