Brain Development Largest, most developed part at birth Weight compared to adult brain 25% at...

• Brain DevelopmentLargest, most developed part at

birthWeight 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

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 experiencesCan 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, languageRight hemisphere

Understanding spatial information Visual-motor information

Corpus callosum connects the two

• Never truly completeChanges 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 BrainGradual and mild degeneration

• Elderly adults5-30% fewer neurons than younger adultGreater loss in sensory-motor areasPlasticity 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 orderlyCephalocaudal: From head, downwardProximodistal: 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 StatesShort sleep-wake cycles at firstEstablish more regularity at 3-6 monthsREM sleep

50% of the time for newborns 25-30% by 6 months

May be useful for reducing stimulation Individuality in infant patterns

• Strengths and weaknessesSensory system intactAbility to learn from experience and

from consequencesLimited 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 ObjectsGrasping reflex disappears: 2-4 moPincer grasp by 6 months

• Motor SkillsRhythmic Stereotypies

Rocking, bouncing, mouthing objects, banging arms and legs

Precede a skill then disappear

• Age 2 until puberty2-3 inches in height, 5-6 lbs weight/per

yearBones grow and hardenRun faster, jump higher, and throw a ball

fartherSkills very responsive to practiceHand-eye coordination, fine motor, and

reaction time all improve

• Education level of parents a factor• Nutrition: Well-balanced diet important

High-carb foods detrimentalChild obesity: Junk-food, TV

• Injuries, auto crashes: Leading cause of death

• Exercise: Promotes physical, cognitive, social well-being, academic skill

• Growth spurt triggered by hormonesPeak 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 laterHeavy and tall mature earlierRegular strenuous exercise mature later

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

• Girls become concerned w/appearance Individual reactions vary widelyNegative views about menstruationOrnamental view

• Boys likely to welcome the changes Instrumental View

• Family relations remain importantDistance and conflict with parents

Usually about only minor issues

• Early males: AdvantageousMore positive reactions from others

• Late/males: DisadvantageousMore behavior and adjustment problems

• Early/females: DisadvantageousSubject of ridicule, lower self esteemOlder 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 problemHigher risk: Diabetes, heart, BP problemsPoor eating habits, sedentary lifestyle

• Leading causes of deathMotor vehicles and violence

• Alcohol and drug use, cigarette smokingAlso 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

lossOsteoporosis in older women

Fair, light frame, smokers Calcium, exercise,

Osteoarthritis: Joint deterioration

• Most systems show decline with ageHeart and lung capacityTemperature control Immune system and strengthReserve capacity

• On average, older people are less fit than younger BUT not all• Physically active remain fit

• Beginning in adolescenceSex hormones influence behavior

Male testosterone Levels fluctuate daily

Female estrogen & progesteroneMonthly cyclePMS? Expectations vs. hormonesCalcium & Vitamin D helpful

• Menopause: Estrogen production declines Age range 45-54Symptoms: hot flashes, vaginal drynessLittle anxiety, irritability, depression, or

other stereotypesExercise and adequate sleep helpful

• Andropause: Decreasing testosteroneSymptoms: 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 RTNovel/complex tasks more difficult

• Physically-fit older people have quicker RT

• Birren (1963) study of men aged 65-91Healthy older same as youngerConclusion: Aging itself has little

effect on physical and psychological functioning

• Disuse: “Use it or lose it!” Includes mental exercise

• Abuse contributes to declineAlcohol, 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 functioningSlows bone loss, strengthens musclesLess depression, delays disability

• Osteoporosis: Smokers, light frame, at risk Increase calciumWeight-bearing exercise

• Osteoarthritis: deterioration of cartilage

• Successful aging Both physical and mental functioning Positive attitude