Prenatal, Birth, and Postnatal Periods Chapter 4 Prenatal, Birth, and Postnatal Periods

The Back Story moment of conception fixes your genetic make-up BUT, from that moment, a single cell begins to adapt to its environment. Within 9 mos. increases in size two hundred billion times!

A Remarkable Story Transaction between special organism Zygote - a single-cell fertilized ovum Unique genetic code Specialized Environment Species Typical Fertilization in fallopian tube (oviduct) Implantation in uterus At birth- billions of specialized cells capable of surviving in complex environment

Three Prenatal Periods Ovum-Germinal Period ~ 2 - 14 days (travel) Embryonic Period ~2 -8 weeks (implantation) Fetal Period 8 -38 weeks (major development)

Ovum-Germinal Period Starts as Zygote in fallopian tube Mitosis produces duplication of cells 32 cell ball called morula Blastula (Blastocyst) differentiates into: Embryoblast (Inner cell mass) – develops into the embryo Trophoblast (Outer protective layer) Becomes amnion, chorio, placenta, allantois (umbilical cord) Ends at implantation in the uterus wall

Reproduction of Cells during Period of the Ovum Duplication of undifferentiated cells As cellular reproduction continues, differentiation begins By the time it enters uterus, two distinct masses have formed See notes on Slide #4

The Blastula Embryoblast Trophoblast Inner cell mass becomes the embryo Trophoblast Outer layer of cells becomes fetal membranes amnion chorion allantois Blastula (or blastocyst)- the embryoblast & trophoblast See notes on slide #4

Implantation Hormones prepare uterine environment Blastula sends out tendrils Marks end of Germinal Period Marks the beginning of Embryonic Period

Three Embryonic Layers Endoderm Innermost Becomes digestive, respiratory, internal organs (pancreas & liver) Mesoderm Center Layer Muscles, bones, circ. system Ectoderm Outermost Hair, Skin, CNS

Period of the Fetus Starts when all basic structures are complete Period of refinement for survival in outside world

Laws of Developmental Direction Cephalo-caudal Head - tail (foot) Proximo-distal Near-far Gross - fine basic - refined

Teratogens Substances or agents present prenatally that cause physical or psychological abnormalities Laws of developmental direction mean that timing is important Generally speaking, those having effects during embryonic development will have greater harmful outcomes

Teratogen Categories Maternal Diseases Drugs Environmental Hazards Maternal Characteristics

Maternal Diseases Toxoplasmosis potentially serious disease caused by parasite in undercooked meat and cat feces Passed to fetus through the placenta Possible Fetal Complications: Visual defects & Blindness Hearing Loss Mental Retardation Seizures Cerebral Defects Low Birth Weight

Maternal Diseases Cytomegalovirus (CMV) Caused by type of herpes virus Passed to fetus as it passes through birth canal of infected mother or through the breast feeding Possible fetal complications (which may appear for the next few years): Mental Retardation Hearing Loss Microcephaly

Maternal Diseases Rubella Caused by a flu-like virus so damaging to the fetus during the first 16 weeks of pregnancy that universal immunization is crucial Passed to the fetus through the placenta Possible fetal complications: (during first 16 weeks after conception): Visual Defects / Blindness Hearing Loss / Deafness Cardiovascular Defects Neurological Defects (including AUTISTIC SYMPTOMS!) growth retardation

Maternal Diseases Genital Herpes viral infection caused by the herpes simplex virus remains in nerve cells causing periodic recurrences Passed to the fetus in 3 ways: 1) through the uterus 2) passing through the birth canal 3) immediately after birth Possible fetal complications: Visual Defects / Blindness Cerebral Defects

Drugs Cigarette Smoking Increases chances of: ectopic pregnancy or miscarriage Low birth weight babies (< 5.5 lbs) results from pre- term delivery and/or poor intrauterine growth Increased risk of chronic disabilities (e.g., cerebral palsy, mental retardation, learning problems)

Drugs Alcohol Intake Even moderate amounts place fetus at risk of: Lower IQ Attention Deficits Learning Deficits Reduced Social Competence First Trimester exposure: skull and facial abnormalities Later in pregnancy: postnatal growth affected

Environmental Hazards Radiation fetal brain most vulnerable to radiation exposure 8th – 15th week of pregnancy Decrease in IQ scores Impaired school performance Susceptibility to seizures Changes in the occurrence of major features of physical development

Maternal Characteristics Maternal Age Malnutrition Effect in Last Trimester Nutritional demands of late fetus is greatest

Postnatal Development

Assessing the Neonate Apgar developed by Dr. Virginia Apgar in 1953. It is administered at 1 minute after birth and again at 5 minutes after birth. A perfect score is 10 see table on page 126 A = Appearance color should be completely pink P = Pulse heart rate should be adequate (over 100 beats per minute) G = Grimace - reflex irritability vigorous cries or withdrawal A = Activity muscle tone should be strong, an active motion R = Respiration a good, strong cry

Assessing the Neonate Brazelton Neonatal Behavioral Assessment Scale (NBAS-R) developed by Dr. Berry Brazelton in 1973 and revised in 2000 A detailed look at the child’s physical and behavioral functioning shortly after birth Used to assess behavioral capabilities of newborns up to 20 days of age Looks at 28 behaviors and 18 reflexes in these 7 areas: Habituation Social Interaction Motor State Organization Reflexes State Regulation Autonomic System

The Ability to Respond to the Environment Sensory Capability - Receptors vision hearing smelling tasting feeling Sensation - firing of receptors by stimulus Perception - interpretation of sensory input

Nativism versus Empiricism Nativism - innate - nature Empiricism - experience - nurture Behavioral Systems Approach – Perception is due to both

Research on Infant Sensory/Perceptual Capabilities Common to all methods - Change in Behavior correlated with change in Stimulus

Methods of Perceptual Research Visual Preference (Fantz) Visual Cliff (E. Gibson & Walk) Habituation-Dishabituation Operant Conditioning Procedures

Visual Preference Looking Chamber Reflection of stimulus on cornea The “Basic Problem” Change in behavior - time gazing Change in stimulus - different visual stimuli Limitations – There may be perception even though there is no preference

Looking Chamber - Fantz

Visual Cliff Depth Perception “Deep” vs. “Shallow” end Mother entices the child to crawl Limitations Child or kid must be ambulatory Overcome by monitoring heart rate of babies suspended over each end (Campos)

Visual Cliff - E. Gibson

Habituation-Dishabituation Babies can’t suck & listen (watch) at same time. Establish sucking response Disrupt it with repeated stimulus (e.g., “Pa”) With repetition of Pa, child habituates sucking returns A new stimulus (e.g., “Ba”) is introduced If child perceives difference between Ba & Pa, sucking stops - Dishabituation

Operant Procedures Behaviors which are reinforced become more frequent Researcher reinforces response to one stimulus and not to another If child perceives difference between stimuli than will respond more to reinforced stimulus

Operant Conditioning Procedures Perception Responses: e.g., head turning, sucking, kicking Reinforcers: e.g., mother’s voice, milk, visual stimuli, heartbeat. Memory & Cognition Kicking mobile in presence of an X produces conjugate reinforcement In later testing immediate kicking when X is present shows recall of contingency (remembering)

Operant Conditioning Procedures Early Perception Dr. Seuss passages read by mothers in last trimester. Infants suck to produce mother-read passages. Early Socialization Infant social referencing.

Perceptual Abilities as Universal Behaviors Some abilities are hard wired Examples Detect light from dark Detect horizontal from vertical Detect sound (phoneme) boundaries

Reflexes as Universal Behaviors Hard - Wired Present at birth Do not need much experience Unlearned thus “Unconditioned” Reflex is not a behavior but stimulus- behavior relationship

Examples of Reflexes Consummatory Defensive Social

How Do Reflexes Change? 1. Reflexes May Stay the Same 2. Reflexes May Disappear 3. Reflexes May Be Elicited by New Stimuli - Respondent Conditioning 4. Reflexes May be Elaborated into New Behaviors - Operant Conditioning

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