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• 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 PLAY VIDEO Dendrites Dendrites CellBody Body Cell Axon Axon Synapse Synapse Neurotransmitters 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 Right hemisphere Analytic reasoning, language 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 • Elderly adults • Gradual and mild degeneration 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 Primitive reflexes: Less adaptive Breathing, eye-blink, sucking/rooting 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 • Boys likely to welcome the changes • Individual reactions vary widely Negative views about menstruation Ornamental view Instrumental View Family relations remain important Distance and conflict with parents Usually about only minor issues • Early males: Advantageous • Late/males: Disadvantageous • • More behavior and adjustment problems Early/females: Disadvantageous • More positive reactions from others 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 • Leading causes of death • Higher risk: Diabetes, heart, BP problems Poor eating habits, sedentary lifestyle 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 45-54 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 65-91 • Disuse: “Use it or lose it!” • Healthy older same as younger Conclusion: Aging itself has little effect on physical and psychological functioning 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