chapter 4: prenatal development Flashcards
prenatal development
the development of humans before they’re born
postnatal development
the development of humans after they’re born, especially in infancy
stages of prenatal development
o Zygote – first two weeks
o Embryo – 2-10 weeks (the period when organs develop)
o Foetus – after week 10 until birth
indirect methods for studying prenatal development
non-human models of prenatal changes in brain and behaviour + human embryos and foetuses that died + testing perception and memory of neonates (infants who’re less than a month old)
direct methods of studying prenatal development
measurement of autonomic nervous system activity with external stimulation + phenotypes (characteristics, capacities and patterns of activity) + placing a foetal ultrasound cardiotocograph sensor around the maternal abdomen that can record the heartrate and movement + using fMRI and MEG
aproptosis
programmed death of cells
when does organogenesis end
8 weeks
stages of zygote
o Zygote – day 1, fertilized egg
o Morula – day 3, ball of 16 cell, cell differentiation starts
o Blastula – day 4-7, cavity arises, embryo arises out of inner cells, implantation in uterus
what’s gastrulation
formation of the 3 germ layers by migration and differentiation of blastula cells
layers of blastula cells
ectoderm - skin, hair and nervous system
mesoderm - muscles and bones
endoderm - most other organs
neurulation
ectoderm - neural plate (18 days) - neural tube (cranial-caudal organization)
when are cells for different parts of the brain differentiated
18 days
what happens when the closing of the neural tube fails
spina bifida (open back) + anencephaly or open skull (usually miscarriage or death shortly after birth)
folic acid during first 12 weeks - helps
neurogenesis
the birth of neurons
cerebral cortex
the area of the brain that is associated with complex tasks (memory, language, thoughts, control and integration of movement and the senses)
when do cerebral hemispheres begin to arise
9 weeks
when do the cells in the cerebral hemisphere proliferate and migrate
4 months
when is the surface no longer smooth and what appears then
6 months, sulci (groove), gyri (ridges)
when does the process of inhibition become function and what happens then
15 weeks - period of reorganisation of behaviours – reflexive neuronal circuits are still in place, now controlled by more sophisticated nerve cells in the new higher centres
when is the number of cells in the cerebral cortex mature
27 weeks - but at birth the brain is only at about 25% of its full adult volume (myelination)
lobes and their function
Frontal lobes – associated with movement, parietal lobes – sensations, temporal lobes – hearing, memory, sense of self and time, occipital lobes – visual centre of the brain
+Association cortex – surrounds the primary sensory areas, longer development (concerned with higher cognitive and integrative function that develop with experience)
what brain regions are the same and different than adult?
Same – sensory and motor networks
Different – emotion and control
pattern of rest and activity at 34 weeks
20-30% of their time in quiet, motion-less sleep with a steady heartbeat and breathing movements that are rhythmic
rest of the time - the same as newborn active sleep - many different body movements, eyes moving rapidly back and forth + heart and breathing rate are irregular + responsive to the sensory stimuli they’re exposed to +fewer general body movements + breathing movements
does the baby move at 38 weeks
longer periods of deep sleep - rest periods of about 80-100 minutes
development of touch
8 weeks – if the area around the lips is stroked – foetuses will respond by moving
10 weeks – foetuses will curl their fingers in a reflexive grasp when their palm is touched
12 weeks – their toes will curl when soles are touches
rooting reflex
the reflex that causes newborn babies to respond to one of their cheeks being touched by turning their head in that direction – helps them nurse
chemosensory system
encompasses both the gustatory (taste) and olfactory (smell) senses
how can infants experience taste stimulants
mouth, nose, blood
when are nose plugs gone
4th month
when is the constitution of amniotic fluid is increasingly dependent on foetal urination
second ja; f pf tje [regmamcu
are some taste preferences learned in utero
yes, newborns turn their heads in the directions of smells present in their mother’s diet (anise, garlic, carrot juice)
colostrum
the breast fluid that comes before true milk – rich in minerals and antibodies, helps populate the newborn’s gut with good bacteria
vestibular system
the sensory system that contributes to balance and spatial orientation
when do infants show the righting reflex and what is that useful for
25 weeks - turning their heads downwards for birth
when do babies move
when the mother isn’t - vestibular stimulation
preterm
born prematurely, anything before 38 weeks
what’s improved if the incubator is rocked
weight gain, visual responsiveness, and later expressive language development
circadian rhythm
bodily cycles within the body that occur on a 24-hour cycle
what’s kangaroo care
skin-to-skin contact between the mother and the preterm infant over 24 days
when are eyelids no longer fused shut
5-7 months
when do eyes start forming
5th week
how do eyes develop
balloons fold inwards, retina develops (function – capture the light entering the eye through rods and cones (develop from the optic cup) and convert it into electrical impulses) + the outer wall forms a pigment-containing layer that absorbs the light + nutritive network of blood vessels
timeline of eye development
2nd month – the lens begins to develop + the eyelids and muscles that move the eyes + the iris
3rd month – the eyelids have fused together + the cornea is forming layers
6th month – all the muscles that move the eyeball are in place
16th to 23rd week - eye movements begin
can premature babies see
26 weeks yes - distinguish light from datk
the visual pathway
connects the light-sensitive cells in the eye (rods and cones) to the brain – deals with the transmission and interpretation of the electrical impulses encoding the visual information that enters the eye
what’s the relay station
lateral geniculate nucleus of the thalamus
when do the nerve fibbers interconnect with the LGN
end of the first ttimester
straite cortex
in the occipital lobe, part of the brain concerned with basic visual function
Surrounding areas – perceptual processes – interpretation of sensory information (development by the end of the third trimester)
when does the development of the auditory system begin
6th week
what can fetuses hear
mother’s heartbeats, borborygmi (gastrointestinal sounds), mother’s voice
when do foetal motor and heart rate responses to external sounds start
26th week
transnatal learning
learning that occurs during the prenatal period which is remembered during the postnatal period
what was found about habituation in the prenatal period
35th week is important
35-37 weeks habituated and dishabituated, 32-34 weeks just mostly habituated
research on hearing heartbeats
Intrauterine sounds calm neonates – but some research called the soothing effect of heartbeat sound into question (failure to replicate + neonatal arousal response to sound dependents upon many variables such as characteristics of the stimulus, infant’s initial state and the experimenter’s choice of response)
how do infants react to mother’s voice compared to a stranger’s voice 2 hours after birth
more movement + sucked to activate the recording of it more frequently
when can infants discriminate languages
4 days after birth, 2 days old show a preference for their maternal language
critical period
Period with specific development is optimal (sensitive period)
Period in which system is vulnerable for lesions
perinatal
just before and after birth
breakdown of congenital defects
10-15% - genetic factors
10% - environmental agents
what causes chromosomal defects
an error in the separation of chromosomes into appropriate daughter cells: meiotic cell division – the type of cell division that occurs in sexually reproducing organisms which halves the number of chromosomes in reproductive cells
risk for Down’s syndrome by age
at 20 is 1/2000, at 30 it’s 1/1000, by 37 it’s 1/200
what can the age of the father cause
schizophrenia, autism, dwarfism
autosomal genetic disorders and examples
resulting from a mutation in a gene in one of the non-sex chromosomes
Sickle cell disease, cystic fibrosis, Tay-Sachs disease, Huntington’s disease, Marfan syndrome
Ashkenazi Jews – 1/30 is a carrier of Tay-Sachs disease, African Americans – 8/100 carriers of the sickle cell gene
adverse outcomes of heavy maternal alcohol consumption
risk for spontaneous abortion, stillbirth, premature placental separation, intrauterine growth restriction, preterm birth, poor development, newborn mortality + risk for SIDS
how many children of Addis get foetal alcohol syndrome
6%
factors linked to severity of FAS
mother’s drinking behaviour (hard to say how much is harmful), timing of the consumption, mother’s alcohol metabolism (faster digestion – less damage), mother’s age, genetic predisposition, mother’s lifestyle
prenatal influence of smoking
Babies weigh 100-200g less + twice the risk for foetal growth restrictions + risk for prematurity and perinatal complications (premature detachment of the placenta) + two to threefold increase for SIDS + o Behavioural problems and cognitive weakness + problems with attention, visuoperceptual processing and speech processing
SSRI
Selective serotonin reuptake inhibitior (SSRI) – a class of drugs used to treat depression or anxiety
microcephaly
small skull, limited brain growth (often in combination with intellectual disability and organ defects)
- Zika virus: spread by mosquitoes, >1000 cases where the mother was infected and the child developed microcephaly
what are calcium and iron needed for
calcium - for foetal bone, muscle and transmitter production
iron - red blood cell and tissue production
developmental programming
the hypothesis that prenatal conditions have detrimental effects on health into adulthood
timing of nutrition - diseases
o Early – diabetes, CVD, breast cancer, depression, schizophrenia, obesity
o Middle – diabetes, lung diseases, kidney diseases
o Late – diabetes
dutch pregnant women in WWII
risk of having schizophrenia, antisocial personality disorder or mood disorder (2nd and 3rd trimester)
reflex behaviors at birth
breathing, rooting, sucking, swallowing + toe-curling reflex, finger-grasping reflex, startle reflex + stepping reflex
