brain facts chapter 7: infant, child, and adolescent brain

how might schizophrenia result from errors in development during early life

it might actually occur because pathways in the brain and connections to it formed incorrectly in early life

genes that influence brain develpoment could play a role in a person's susceptibility to what type of disorders

autism spectrum disorders

what is the average brain weight of a newborn human baby

~370 grams

what is the percent growth rate of the brain immediately after birth? what about after 3 months after birth

immediately after birth it is 1% per day, at 3 months it is about 0.4% per day

what is the fastest growing brain region at birth

the cerebellum

how much has the cerebellum increased in size between birth and 90 days

it has more than doubled its volume

By the time a baby is 90 days old, its overall brain volume is ___ percent larger than it was at birth

64

During the first three months of life, the number of neurons in the cortex increases by what percentage

23-30%

why does white matter in the brain appear white

the color is due to all the myelin wrapped nerve fibers in those areas

by the time the brain is 5 years old, it has reached about ___ percent of its adult size

90

a 2 year old's brain has ___ percent ______ (more/less) synapses than an adult brain, despite only being about ___ percent the size of an adult brain

50; more; 80

what is the synaptic pruning process shaped by

toddlers' experience as they grow

which connections diminish during synaptic pruning

weaker connections (less activity)

Compared to other animals, humans are born with _____ (more/less) developed brains, and human brains take _________ (longer/less time) to mature

less; longer

at what age do squirrel monkeys reach their adult brain size

6 months old (!)

what is one advantage of having a brain that takes longer to develop

the brain is more easily shaped by environment and experience, helping us adapt appropriately to the surrounding environment

what are critical periods

periods of development where inputs from sensory, motor, and even emotional aspects of life experiences affect how the brain develops and adapts to the given environment

both ______ and ______ exert strong influences during critical periods

genes; environment

changes in neural connections during critical periods coincide with what

high rates of learning, such as a toddler learning to run or to speak multiple languages

what is competitive elimination in synaptic pruning

stronger connections beat out weaker ones

what structural changes happen to neurons in the frontal lobes of adolescents

they grow out their dendrites and myelinate their axons

what are longitudinal studies

ones that track subjects over extended periods of time

what is one important thing related to development that longitudinal studies are capable of revealing

they reveal how early life events and environment can affect outcomes later in life, like education or risk for disease

what happens to the corpus callosum in adolescents

it increases in the volume of white matter it has

the growth of the corpus callosum in adolescence may explain what

enhanced learning capabilities during this period

what are increased risk taking and sensation seeking an aspect of in adolescents (what enhanced ability)

an enhanced ability to learn

risk taking and sensation seeking in teens increases the risk of what disorder

addiction

what is frequent drug use in adolescence associated with in relation to the brain

damage to brain regions important for cognitive functions such as memory, attention, and executive functioning

what is damage to brain regions important for cognitive functions such as memory, attention, and executive functioning linked to in adolescence

frequent drug use

what is diffusion tensor imaging used to study

the quality of white matter

adolescents who used alcohol showed what different qualities about their white and gray matter as opposed to those who didn't

they had reduced gray matter volume and reduced white matter integrity

lower brain activity, less sustained attention, and poorer performance on a working memory task were associated with what behavior in adolescents

binge drinking

what are some consequences of binge drinking during adolescence

lower brain activity, less sustained attention, and reduced working memory

human brains continue to develop until about what age

30 years old

what brain area increases in gray matter density until age 30 while most other areas decrease

the left temporal lobe

brain development in your 20s includes what change involving myelination

changes in where myelination occurs

what is another function of myelin besides speeding up the rate of action potentials

myelin protects the axon

what areas are myelinated around 30 yrs old? What about earlier in life

when your 30 the frontal and parietal neocortices become more myelinated. Earlier in life more myelination is found in the visual, auditory, and limbic cortices

what is -- and what is the significance of -- the different pattern of myelination that arises as you get closer to 30 yrs old

there's more myelin in the frontal and parietal neocortices, which helps with working memory and higher cognitive functions

what is plasticity

ability of the brain to modify itself and adapt to environmental challenges

if you didn't have plasticity what would be different about development

you wouldn't have critical periods and you wouldn't really develop according to your environment

to what extent is plasticity unique to humans

other animals have plasticity, but our brain's capacity to adapt is a defining attribute of human beings

what process allows for critical periods and brain changes during development according to the environment

plasticity

what is experience-expectant plasticity

integrating environmental stimuli into normal developmental patterns

what are some environmental experiences that must occur during limited critical, or sensitive, periods for healthy brain maturation

hearing language, seeing faces, being held, etc.

finches that don't hear adult songs before sexual maturation won't be able to do what as well as finches that did

sing

what does experience dependent plasticity describe

it describes continuing changes in the organization and specialization of a person's brain regions as a result of life experiences that are not universal or anticipated

what is the difference between experience expectant and experience dependent plasticity

experience expectant plasticity involves universally experienced environmental stimuli (ike being held, hearing voices, or seeing faces). Experience dependent plasticity involves environmental stimuli that are different for different individuals

not everyone will play the violin, but violinists often show greater cortical development in the brain region associated with the fingers of the left hand. What is this an example of (note the fact that not everyone plays the violin)

experience-dependent plasticity

what can two-photon imaging allow you to do that other techniques can't

it can allow scientists to observe living neurons in animals with a microscope and track their growth after various experiences

can experience dependent plasticity occur during adulthood

yes