L&D 2/2 Flashcards
What is differential brain development?
It takes different amounts of time for different parts of the brain to grow to their full size
By how much does the brain increase in size from birth to teenage-hood?
4x
What % of the body is the brain and what % of the O2 inhaled does it use?
2% and 20%
What % of an infant’s body weight is its head?
25%
How many neurones does the brain have at birth?
100 billion+
What are the 3 trimesters of prenatal development?
Zygote - 2wks
Embryo - 3-8wks
Foetus - 8wks-birth
What is the germinal stage?
Where the zygote is formed and implants in the uterus wall
What is the embryonic stage?
amniotic sac, placenta and umbilical cord develop
What are the 3 primary germ layers and what parts of the infant do they become?
endoderm - digestive system
mesoderm - muscles, skeleton
ectoderm - CNS
What is neurulation?
Where the neural tube (formed from the neural fold) forms the brain and the spinal cord
What is neurogenesis?
Where neurones are produced for specific functions
What forms the hindbrain, midbrain and forebrain?
The cranial end of the neural tube
When does neurogenesis and cell migration continue until?
6 months of gestation
How many neurones are added every minute in neural proliferation?
250,000
What is the foetal stage?
3months to 27wks 3m - all body parts present 5m - reflexes 6m - eyes open and close, sulci+gyri appear 22-26wks - viability
What are the 6 stages of brain development?
- neurogenesis
- migration
- differentiation
- aggregation - formation of specialised regions by neurones
- synaptogenesis
- Competition among synapses - synaptic pruning
What is the last thing to develop in a foetus?
The cortex
What are the 3 milestones of prenatal development?
12wks - breathing established
23wks - sleep-wake cycle established
30wks - 70%-80% REM sleep
What are the milestones of prenatal motor development?
7wks - movement detected by ultrasound 8wks - startle response 9wks - arm and leg movements 10wks - head movements, hand-face contact 12wks - move fingers independently 14wks - hand rotation 15wks - 15 different movement patterns 16wks - movements felt by mother 18wks - eye movements 17-24wks - quiescent period (no movement) 24wks - thumb sucking 26wks - eyes open
What is teratology?
Study of congenital abnormalities and abnormal formations in foetuses
What is a teratogen?
An agent that causes developmental deviations
Give a few examples of teratogens and their effects
drugs (aspirin - low IQ, poor motor control, caffeine - risk of miscarriage, heroine/cocaine - addicted babies)
smoking (spontaneous abortion, prematurity, low weight)
disease
radiation (cell death, chromosome injury)
metals (lead, mercury)
parental factors (age - downs’ syndrome, diet, emotional state)
How does the Zika virus affect foetuses?
can cause microecephaly, pre-term birth and miscarriage
What is microecephaly?
bellow average head size ( less than 31.5-32cm at birth)
poor feeding
seizures
developmental delay
What is lissencephaly?
‘smooth brain’ - lacking gyri and sulci
caused by defective neural migration due to viral infection OR genetic anomaly
seizures
developmental disabilities
What if foetal alcohol syndrome? What differnce does it make if taken in 1st trimester vs. 3rd?
distinct facial features CNS damage learning disabilities 1st trimester - impaired brain cell organisation 3rd trimester - impaired brain function
What did Kelly et al. (2009) say about mild drinking during pregnancy?
It could have positive effects (1-2 units p/w)
What is the deal with Thalidomide?
Drug given to help with morning sickness in 1950s-60s BUT
inhibits blood vessels around day 24-28 causing limb deformation
~10,000 cases in 46 countries
What is the deal with agent orange?
~4 million people exposed 1960s-80s
associated w/ mental health issues, cleft palette, polydactyly
What is the evidence for transnatal learning taking place inside the womb?
Increased alertness
Change in movement
Slowed heart rate
Demonstrated preference via sucking techniques
What did Hepper (1998) find in their ‘Neighbours’ fans’ experiment
Babies exposed to Neighbours in the womb showed signs of interest when the theme tune was played 2-4 days after birth
No interest in other theme tunes
What did Hepper (1991) find in their continuation study?
After 21 days from birth the babies no longer ‘remember’ the tune
What did Querleu et al. (1984) find about an infant’s reaction to its mother’s voice?
A 2h old infant will react to its mother voice preferentially to that of a stranger
What did Spence and Freedman (1996) find about babies’ preference when hearing their mother’s voice?
Babies prefer low-pass filtered mother’s voices to unfiltered as it more closely resembles what they hear in the womb
What did Mampe et al. (2009) find about accents in the womb?
2-5 day old infants prefer listening to their own language even just as a melody contour
infants’ cries mimic the prosody of their own language
What did Morokuma et al. (2008) find about hearing in the womb?
Habituation and dishabituation to auditory stimulation occurs at 35-37wks but now 32-34wks
What is the neonatal experience of being born referred to as by scientists?
confusing, bright and disorientating
What did Gopnik (2009) say about babies’ consciousness?
They have ‘lantern consciousness’ that narrows with age
What are some characteristics of neonatal reflexes?
Most disappear soon after birth
They re-emerge as voluntary movements later in development
What is the Moro reflex?
If a baby is dropped or hears a loud noise it will extend its limbs and head back
What is the Rooting reflex?
If their cheek is brushed the child turns in that direction - evolved to aid breastfeeding
What is the grasping reflex?
make a fist when palm is stroked
What is the stepping reflex?
When a baby is held under its arms, bare feet touching a flat surface and it makes step-like movements
What is infant swimming?
a reflex that resembles swimming but is not
coincides with a bradychardic (slow heart rate + breathing) response and laryngeal reflex to stop water entering the lungs
disappears around 6 months
What are some of the methodological problems facing experiments with children?
infants cannot speak or fill in questionnaires
What are the main experimental techniques used with children?
looking time methods preferential looking high aptitude sucking preferential sucking EEG ERP Eye tracking
What are looking time methods?
Habituation and dishabituation to seen objects
What did Lewis et al. (1969) discover about habituation?
habituation rate is considered an indication of cognitive competence - older infants habituate faster
What did Colombo et al. (2004) discover about habituation and IQ?
There is a predictive correlation between habituation in infancy and IQ up to the age of 11
What is preferential looking?
2 stimuli are presented, time looking at each is recorded - any preference suggests infants can discriminate
What is high amplitude sucking?
dummy with a pressure transducer measures rate and pressure of sucking suggesting interest in a stimulus
What is preferential sucking?
sucking on a dummy keeps stimulus 1 present, stimulus 2 appears when sucking stop. Can therefore determine which stimulus the infant prefers
What is a newborn’s auditory and visual perception like?
auditory perception is good
visual acuity is poor
By what age does trichromatic vision develop?
2 months
By what age does ‘adult-like’ vision develop?
4 months
What did Slater et al. (1983) find about infants’ 2D shape perception?
They habituated infants to 1 of 4 shapes, then presented the habituated shape with a new shape and found infants stared longer at the new shape showing that they recognise the difference
What did Slater et al. (1991) find about infants’ whole shape perception?
They habituated infants to angles in different orientations and found that there was a novelty preference for different angles
What did Ghim (1990) find out about infants and perceptive contours?
Infants habituated to a square by subjective contour meant they looked longer at a triangle subjective contour than a square when shown after habituation
What is a subjective contour?
Where a shape is not drawn it appears present by the placing of other shapes or lines in order to create the illusion
What did Slater&Morrison (1985) and Slater et al. (1990) say about infants’ ability to perceive constancy at different distances?
They said infants are able to do this
What did Salapatek (1975) discover about infants’ face perception?
studied how infants scan the human face and how this changes as visual acuity improves
young = all around the face
older = eyes + mouth
What did Frantz (1961) find about neonates and face preferences?
They prefer schematic faces
What did Bushnell et al. (1989) find about infants and their mother’s face?
Infants focus preferentially on their mother’s face than that of a female stranger
Why did Walten et al. (1992) criticise Bushnell et al. (1989) and what did they do to resolve it?
Argued in B’s study it could have been the mother’s smell or bodily cues instead of the face
did the same study but with video footage of mother and stranger instead
What did Gava et al. (2008) find about the types of faces babies prefer?
They prefer average faces
What did Pascalis, Haan&Nelson (2002) find about young infants and monkey face discrimination? What does this tell us about face perception?
6m old babies can discriminate between macaque faces - this skill is lost by 9m.
perceptual narrowing occurs through experience
What did Simeon et al. (2008) show about infants and motion discrimination?
By 2 days old neonates can discriminate biological from non-biological motion
What did Meltzhoff&Borton (1979) find about integration of infants’ senses?
Babies given either a ridged or smooth dummy without seeing which one searched more for the one they were given when it was taken away - cross-modal matching
What did Walker et al. (2010) find about synaesthesia in infants?
suggests synaesthesia is innate but disappears over time
What did Adolph&Robinson prove wrong about infants and motor development?
Infants move to get what they want
Motor development occurs sequentially i.e. later forms of movement develop from earlier ones (sitting –> crawling –> walking)
Both are wrong
What did Adolph&Franchak (2014) find about affordances for action?
The fit between and animal’s capabilities and features of the environment make actions possible - these affordances change as a baby goes from sitting to crawling etc.
What did Adolph et al. (2012) say about natural walking?
It is usually not for a defined goal
