Download 4 - Florida International University

Chapter 4
Prenatal, Birth, and Postnatal
Periods
A Remarkable Story
• Transaction between special organism
– Zygote
– 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
– ~ 2nd - 14th day
• Embryonic Period
– ~2nd-8th week
• Fetal Period
– 8th -38th week
Ovum-Germinal Period
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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
The Blastula
• Embryoblast
– Inner cell mass
– becomes the embryo
• Trophoblast
– Outer layer of cells
– becomes
• fetal membranes
– amnion
– chorion
– allantois
• Blastula (or
blastocyst)- the
embryoblast &
trophoblast
The BlastulaBasic Structures
Implantation in Uterus
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Hormones prepare uterine environment
Blastula sends out tendrils
Only 1/2 of zygotes implant
Phase shift in development
A Developmental Cusp
Marks end of Germinal Period
Marks the beginning of Embryonic
Period
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
Benefogens
• Coined term for agents present during
prenatal development having a
beneficial outcome
• E.G.:
– AZT (Zidovudine – ZDV)
• HIV infection
– Folic Acid
• Neural tube disorders (spina bifida)
Teratogen Categories
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Maternal Diseases
Drugs
Environmental Hazards
Maternal Characteristics
Maternal Diseases
– Toxoplasmosis
– Cytomegalovirus (CMV)
– Rubella
– Genital Herpes
Drugs
• Cigarette Smoking
• Alcohol Intake
Environmental Hazards
• Radiation
Maternal Characteristics
• Maternal Age
• Malnutrition
– Effect in Last Trimester
– Nutritional demands of late fetus is
greatest
Reproductive Risk versus
Caretaking Casualty
• Reproductive risks - pre & perinatal
events
– Impaired - unimpaired
• Caretaking Casualty - postnatal events
– nonfacilitative - facilitative environment
– vulnerable - nonvulnerable organism
Postnatal Development
The Remarkable Newborn
Assessing the Neonate
• Apgar
• Brazelton Neonatal Behavioral
Assessment Scale
– NBAS-R
• 28 behavioral
• 18 Reflexes
• 7 Areas:
– Habituation, social interaction, motor, state
organization, state regulation, autonomic system,
reflexes
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
How Do We Know the
Sensory/Perceptual
Capabilities of the Infant?
• Common to all methods - Change in
Behavior correlated with change in
Stimulus
Methods of Perceptual Research
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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 – The Coke vs. Pepsi Problem
• There may be perception even though there is
no preference
Looking Chamber - Fantz
Visual Cliff
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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
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 stimulusbehavior relationship
Examples of Reflexes
• Consummatory
• Defensive
• Social
Consummatory Reflexes
(Watson (1920) eliciting rooting reflex)
• Search
Defensive Reflexes
Watson (1920) eliciting Babinski reflex)
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
End of Chapter 4