Genotype
Refers to a person’s genetic make up;
Phenotype
Refers to observable characteristics, which are due to a combination of genetic and environmental factors
Bronfenbrenner’s Ecological Model
Described development as involving interactions btwn the indiv. & his/her context or environment.
This model distinguishes btwn 5 environmental systems or levels:
Rutter’s Indicators
Argued that the greater the number of risk factors a baby is exposed to, the greater the risk for negative outcomes. He concluded that the following 6 family risk factors are particularly accurate predictors of child psychopathology:
Resilience (Werner and Smith)
Longitudinal research found that exposure to early (prenatal & perinatal) stress may be reduced when the baby:
Critical and Sensitive Periods
Some aspects of human development may depend on critical periods, but,
for many human characteristics & behaviors, sensitive periods are probably more applicable.
Prenatal Development
3 stages of prenatal development:
Birth defects are caused by chromosomal D/O’s, exposure to tetatrogens & poor maternal health.
Autosomal Disorders
When a D/O is carried on an autosome (22 pairs of chromosomes). All human cells (except sperm & ovum) contain 46 chromosomes arranged in 23 pairs.
Sex Linked Disorders
When a D/O is carried on sex chromosomes
Ex: Klienfelter Syndrome & Turner Syndrome
Disorders due to Dominant & Recessive Genes
Disorders related to chromosomes are the result of inheritance of a single dominant or 2 recessive genes or a chromosomal abnormality.
Phenylketonuria (PKU)
Autosomal recessive condition (Homozygous, 2 recessive genes); 1 recessive gene from each parent.
Caused by a pair of recessive genes & produces mental retardation unless the infant is placed on a diet low in phenylalanine soon after birth.
Phenylalanine an amino acid found in milk, eggs , bread can cause MR unless the infant is put on a special diet soon after birth.
Down Syndrome
Autosomal Disorder
Caused by an extra number of 21 chromosome.
It is characterized by mental retardation, retarded physical growth & motor development, distinctive physical characteristics, & increased susceptibility to Alzheimer’s dementia, leukemia, and heart defects.
Klinefelter Syndrome
Occurs in males & is due to the presence of 2 or more X chromosomes along with a single Y chromosome (due to an abnormal level of sex chromosomes).
Males with this disorder have:
Turner Syndrome
Occurs in females when 1 X chromosome is missing or incomplete (due to abnorm # of sex chromosomes).
Charateristics include:
Prader-Willi Syndrome
Caused by a chromosomal deletion on the paternal side & includes:
Teratogens
Env. agents that adversely affect prenatal devel. & cause birth defects in the developing fetus & include:
Exposure during 3-8 weeks (embryonic period) most likely to cause major structural abnormalities.
Prenatal Exposure to Alcohol during 1st Tirmester
Exposure during the 1st Trimester likely to produce severe physical defects.
Res. shows that alcohol exposure during the 2nd half of the 1at Trimester is assoc. w/ most severe physical defects:
Prenatal Exposure to Alcohol during 3rd Tirmester
In the 3rd Trimester alcohol exposure can impact development of attention & other cognitive Fx’s
Fetal Alcohol Syndrome/Effects
Prenatal exposure to alcohol can produce a variety of physical, behavioral, & cognitive Sx’s that, in terms of severity, depend on the amount of alcohol consumed by the pregnant woman.
Maternal HIV
If Mom HIV+ the chances of transmitting it to her child is 35-60%, the risk is greatly reduced when she takes an anti-retroviral drug during pregnancy & delivery.
A minority of babies birn w/HIV devel. severe Sx’s in 1st month after birth, while the rest have a later appearance & slow progression of Sx’s
With Tx infants can survive to 8yrs and beyond
Infected children have delays in physical & cog. devel. & high rates of life-threatening opportunistic infections
Prenatal Exposure to Cocaine
Use of cocaine by a pregnant woman increases the risk for spontaneous abortion & stillbirth.
Infants born to cocaine users are at high risk for:
Malnutrition During Prenatal Development
Malnutrition during prenatal devel. is associated with:
Severe malnutrition in the 3rd trimester (especially protein deficiency) is particularly detrimental for the developing brain & can lead to a reduced number of neurons, reduced myelinization, & neurotransmitter abnormalities.
Good nutrition after birth can reduce some of the negative effects
Congenital Cytomegalovirus (CMV)
Approx. 10% of infants infected w/CMV show Sx’s at birth & about 10-15% of infants who are asymptomatic at birth devel. Sx’s during 1sr few yrs of life.
Brain Development (Cerebral Cortex)
The cerebral cortex is largely undeveloped & least devel. part of brain at birth (25% of adult weight) but shows dramatic growth during the first 2 years of life (approx 80%) as the result of:
Cerebral Cortex responsible for higher level cog. Fx, language, spatial skills & complex motor activities.
The frontal lobes continue to mature into adolescence and the early 20s.
Some neurogenesis (regeneration) occurs in adulthood, especially in hippocampus & brain also compensates for loss of neurons thru axon sprouting, dendrite branching & creation of new synapses
30 yrs of age the brain gradually starts to shrink as a result of loss of neurons & acceleration of brain loss after 60 yrs old in sensory & motor cortex.