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PSYCH 2AA3 (402)
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Prenatal Development.docx

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Department
Psychology
Course
PSYCH 2AA3
Professor
Richard B Day
Semester
Summer

Description
May 9 , 2013 Psych 2AA3: Child Development Prenatal Development Video - “In the Womb” (National Geographic)  Neural development  Reflexes  Sensory development  Learning  Fetal behaviour Conception and Genetics - Homozygous pair  When the two sets of instructions are the same at any given locus - Heterozygous pair  When the two sets of instructions are different at any given locus - Genotype – the genetic blueprint  Information contained in the genes  All of the information regardless if it is expressed - Phenotype – observable characteristics  Expressed genes - Dominant-recessive pattern  Dominant genes always express their characteristics  Dominant homozygous pairs  Or heterozygous  Both recessive genes must be present to express their characteristics - Twins  Identical (monozygotic)  Single egg that has been fertilized and split  Sharing of the placenta depends on how early or late the split has occurred  Identical set of genes (100% of shared genes)  Fraternal (dizygotic)  Two separate eggs released within 24 hours  Fertilized by two different sperms  No more similar than siblings (50% of shared genes)  The case of the vanishing twin  Blood supply to one twin is inhibited killing the second foetus - Twins in genetic research Sex Differences in Prenatal Development - Between weeks 4 and 8, males begin to secrete testosterone from primitive testes  2/3 of sperm are male  Male embryos are more delicate  Males are more likely to result in miscarriage  Males have more disease, earlier death, and shorter lifespans in most of the world  Necessary to develop male genetalia  Lack of testosterone will “demasculinize” the male embryo  The amount of testosterone influences the direction the embryo will take  Chromosomes XX and XY affect the levels of testosterone  Too much testosterone will “defeminize” the female embryo  Females begin producing their eggs in vitro  Grandmothers may have an effect on the outcome of their daughters’ offspring - Prenatal hormones may influence sex differences in:  Brain development  Prenatal testosterone may cause things such as autism  Brain development and lateralization of the brain  Hormones in adolescence  Set up hormone production in adolescence  Levels of hormones in puberty  Levels of physical aggression  Relative dominance of right and left hemispheres  A lot of this research is speculative and largely based upon animal research - Girls  Slightly faster skeletal development - Boys  Slightly heavier and longer at birth  Sets mom’s system to be more cautious the next time she delivers a boy  Increased risk of miscarriage when having a second boy  More vulnerable to prenatal problems  Health problems  Learning disabilities  More likely to be aborted spontaneously  Have more birth injuries and birth defects  X-related problems may be a factor  A lot of disorders are based on defects of the X chromosome  In the case of an XY pair, if there is something wrong with the X there is no other X to rectify the problem  Example: colour blindness is more prevalent in males  Slightly more active before birth  Boys may be beginning the physical practice earlier setting themselves up for more physical activity later on  There is an increase level of activity in preschool-aged boys Prenatal Behaviour - Fetuses respond to sound with body movements as early as 25 weeks  Example: music, ultrasounds - Can distinguish between familiar and novel stimuli by 32 weeks - Learning may begin prenatally (~32 weeks)  “The Cat in the Hat” experiment  Music experiments  After birth, those that were exposed responded differently (more calmly) when they were presented with the stimuli they had been presented prenatally - Music played prenatally may lead to advanced motor and cognitive skills at six months  In line with research suggesting that various types of music exposure and music training are more advantageous later in life  Mozart effect: preforming better on a cognitive task after listening to music  Doesn’t matter what kind of music it is  Music stimulates the brain and improve cognitive development Problems in Prenatal Development - Corresponds to high rate of miscarriage - Genetic disorders  Autosomal disorders  Caused by recessive genes o Phenylketonuria (PKU)  Protein that cannot be metabolized by the protein  Found in breast milk  Causes brain damage  Screened for genes at birth  By altering the diet, we can prevent the brain damage o Sickle-cell disease  Identified as having an evolutionary purpose  Resistance to malaria  Prominent in those of African descent  Where malaria does not exist this gene does not have this purpose  Allowed to carry on in ancestors as it protected them from malaria o Tay-Sachs disease  Tend not to live past the age of 3 or 4  Most commonly found in populations that tend to be more restricted, for example in Jewish populations as they tend not to marry outside of their group  Caused by dominant genes o Huntington’s disease  Most dominant gene disorders find their way out of the population as those who carry them will not end up to reproduce  Huntington’s is not manifested until after reproductive age o Schizophrenia  Tends not to be expressed until later in life o Migraine headaches o Extra fingers o Most disorders caused by dominant genes tend to be those that we can live with such as migraine headaches and extra fingers  Sex-linked recessive disorders
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