Download SR6e Chapter 5

•
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