lecture 14 Flashcards
motor development
between 1-3 months babies display hand movements similar to adults
develop pincer grasp at 10 mo
- emerging behaviors can predict neural maturation
language development
language onset is between 1-2 years around 5-10 words by 1 year around 200-300 words by 2 year around 25000 words by age 6 largely complete by age 12
language and motor development
language and motor skills develop in parallel to some degree but precise movements of muscles controlling speech sounds develop before children can speak
- even when motor skills developed to articulate most words vocabulary still progresses
what are the major changes in language development
neural connectivity and myelination of speech zones
- happens at around 2-12
development of problem solving ability
piaget: sensorimotor (0-2yr), preoperational (2-6), concrete operational (7-11), formal operational (12+)
what are the neural underpinnings of piagets stages
grwoth spurts- sporadic period of sudden growth that lasts for ifnite time
epstein identified 5 spurts, first 4 coincide with piaget
due to growth of gial cells, blood vessels, myelin and synapses
what does development of problem solving abilities tell us about brain development
if children perform a particular task poorly, can infer that brain regions governing task are not fully developed
overman and colleagues
tested children on:
concurrent discrimination task (temporal lobe)
- around 12 m to learn all correct objects
nonmatching to sample (basal ganglia)
around 18 m to learn the pair
experience on brain development
Hebb- how does experience impact brain development
found that rats raised in enriching kitchen performed much better than rats raised in barren environment- more and larger synapses and astocytes
how does experience influence neural connectivity (pre and post natal)
chemoaffinity hypothesis- neurons or axons/dendrites are drawn towards signalling chemical that indicates correct pathway
postnatal- fine tuning of connections proceeds in an activity dependant manner
abnormal expereince on brain development
absence of the right sensory experience at the right time can result in abnormal development
critical period: developmental window when some specific sensory experience has a long lasting influence on the brain
imprinting
process that predisposes an animal to form an attachment to objects or animals at a critical period in development
- enlargement of synapses in chick forebrain
3 experiments on abnormal experience
hebb- raised dogs in dark enclosures –> behaviorally muted and performed poorly on intelligence tests
harlow- seperated monkeys from their mothers –> incapable of forming normal social relationships in adulthood
riesen- showed absence of visual stimulation leads to atrophy of dendrites on cortical neurons
stress in early life
associated with increased amygdala, decreased hippocampus and later development of depression and anxiety
testosterone (androgen)
released during brief period during prenatal development: alters brain as much as alters sex organs
- sexual dimorphism at around 60 days
sex hormone for male
estrogen
sex hormone responsible for distinguishing characteristics of female
what parts of brain development are affected by hormones
number of neurons formed, number of neurons that die, cell growth, dendritic branching, synaptic growth, activity of synapses
- difference in receptors correspond to differences in volume
rats reaered in complex environments- hormones
males showed more dendritic growth in visual cortex, females showed more dendritic growth in hippocampus, - same experience affects male and female brain differently
gut bacteria and brain development
some neurodevelopmental disorders may be related to atypical microbiome
- mouse model of autism returned to normal from manipulation of gut bacteria
- proved gut bacteria can alter behavior
injury and brain development
worst time for brain injury: last half of intrauterine period and first few months after birth
better time: first few years after birth (2) more resilient to deficits than damage in adults
drugs on brain development
ongoing research
- low dosages can have potentially damaging impact on developing brain
genetic abnormalities of brain developmeent
spina bifida- spinal cord abnormality due to the failure of the neural tube to close completely, motor problems
anecephaly- front end of neural tube doesnt close and forebrain fails to develop
abnormal cell migration
schizophrenia- faulty connections produce a range of
- disorganized pyramidal neurons in hippocampus
developmental disability
impaired cognitive functioning due to abnormal brain development
- many causes, genetic abnormalities, prenatal exposure to infections or toxins, birth trauma, malnutrition
mechanism of developmental disabilities
examined brains of children with developemental disabilities and found dendritic growth was reduced
- suggests fewer connections in brain
