Chapter 2

• Genotype: The genetic makeup of an organism, including the alleles it carries

  Phenotype: observable characteristics (physical and psychological traits)
• Behaviour genetics:

  • field that tries to uncover the influence of genes and environment on interindividual differences (not development)
• Two principle studies of gene-environment interactions:

  1. Hold environment constant and vary genotypes (twin studies)
  2. Variation in phenotypes attributable to variations in genotype
  3. Hold genotypes constant and vary environment (adoption studies)
  4. Variations in phenotype attributable to environmental influence
• Heritability: measure of the extent to which a variation in a particular trait among individuals in a specific population is related to genetic differences among those individuals
• Heritability limitations:

  • population statistic
  • particular time and conditions
  • does not inform us about how developmental processes unfold
• Passive correlation: parents provide environments influenced by their own heredity and children inherit characteristics from their parents
• Evocative correlation: children evokes responses form others that are based on the child's heredity
• Active correlation: at older ages, children actively seek environments that fit their genetic makeup
• Epigenetics: study of environmentally triggered changes by modification of gene expression
• Epigenetic inheritance: transgenerational transmission of molecular factors that determine how DNA is read and expressed
• Epigenesis: developmental results from ongoing bidirectional exchanges between heredity and all levels of the environment
• Probabilistic epigenesis: different neural structures develop and activate either based on an individual's biology or interactions with their environment
• 3 themes of prenatal development:

  1. development involves differentiation
  2. development involves repeated reorganization and qualitative change
  3. new structures and capacities emerge in an orderly fashion form those that existed before
• Germinal period (first two weeks):

  • from fertilization to implantation into the uterine wall
  • blastocyst forms
• Embryonic period (6 weeks):

  • rapid cell division and differentiation
  • arms, legs, face, organs, muscles begin to develop
  • heart begins to pump blood
• Organogenesis: embryonic disk forms 3 layers of cells

  1. Endoderm (digestive system, lungs)
  2. Mesoderm (muscles, circulatory system)
  3. Ectoderm (skin, neural tube)
• Fetal period (30 weeks):

  • growing and finishing phase
  • connections between muscles, organs, and nervous system
  • brain firing leads to diverse movement
• Main events in prenatal neural development:

  1. neuronal production or proliferation, overproduction
  2. Neuronal migration
  3. Neuronal specialization and differentiation
• Teratogen: environmental agent that causes damage during the prenatal period; impact depends on dose, genetic susceptibility, and time of exposure
• Fetal alcohol spectrum disorder: a range of disorders caused by prenatal exposure to alcohol

  • growth retardation
  • facial abnormalities
  • areas of functioning impaired
  • alcohol interferes with prenatal neural production
• Thalidomide: A drug used to treat morning sickness in pregnant women

  • when taken 4-6 weeks after conception, produced gross deformities of embryo's arms, and legs, less frequently damage to ears, heart, and kidneys
• Maternal stress:

  • Psychosocial stress can lead to miscarriage, low birth weight, infant respiratory illness, cognitive and emotional problems
  • stress-induced maternal vasoconstriction leads to lower fetal oxygen and nutrient intake
  • maternal stress and anxiety = fetus increased heart rate
• Cocaine:

  • prematurity, low birth weight, breathing difficulties
  • drug addicted: feverish and irritable at birth
  • Interpret with caution: other factors in the lives of pregnant women who use cocaine often cannot be ruled out as possible contributors to the problems found in their children
• Fetal alcohol syndrome:

  • growth retardation
  • 3 facial abnormalities
  • CNS abnormalities
• Partial fetal alcohol syndrome:

  • two facial abnormalities
  • brain injury or growth retardation or pattern of cognitive abnormalities
• Alcohol-related neurodevelopmental disorder:

  • area of functioning are impaired
  • behaviour or learning problems, intellectual disability
• Permanent mental impairment in FASD:

  • low IQ
  • language and motor problems
  • executive functioning defecits
  • poor school performance
  • externalizing and internalizing problems
• Stages of childbirth:

  1. Regular and strong contractions
  2. dilation and effacement of cervix
  3. Pushing and crowning to deliver baby
  4. head of baby pushes through cervix into vagina
  5. Birth of placenta
  6. afterbirth
• Apgar scale: assess the physical state of newborn

  • heart rate
  • respiratory effort
  • reflex irritability
  • muscle tone
  • skin colour
• Small-for-date infant: below expected weight given gestational age
• Interventions for pre-term infants:

  1. Parent-child relationship
  2. Infant stimulation (massage, kangaroo care)
  3. Training parents in infant caregiving skills
  4. Resilience in the context of good quality home environment, positive relationships to persons outside the family
• Consequences of low birth weight:

  • more likely to have serious problems
  • catch infections, brain damage, low IQ
  • higher risk of sudden death
• Bonding: instantaneous strong feelings of affection for newborns