brain development and plasticity

Question 1

what brain processes happen during development

Answer 1

cell proliferation and migration
development of synapses
myelination

each process has their own time course (some happen at birth, others through adolescence)

Question 2

neurulation

Answer 2

formation of the hollow tube that becomes the CNS

with time, the tube folds,turns and expands to become the fetal brain

the hole inside the tube becomes the ventricles

around the 7th week of gestation, nerve cells and glia near inside tube divide, proliferate and begin to migrate outward

Question 3

neurogenesis

Answer 3

generation of new nerve cells occurring in the area right around the ventricle

Question 4

migration of nerve cells

Answer 4

happens during early development

glial cells provide the scaffolding or “roads” along which nerve cells can migrate to their ultimate destinations
- cells that migrate often travel along radial glia

by six months of gestation, most neurons have been produced

Question 5

synaptogenesis

Answer 5

dramatic increase in the number of neuronal connections (synapses)

one of the largest changes after birth

dendrites in the cortical regions increase greatly, providing greater SA for synaptic connections

occurs rapidly (increase more than 10 fold during the first year of life)

regional differences across brain regions
- occurs most rapid in primary sensory and motor area (functionally needed before learning more complex things) then the prefrontal cortex

Question 6

synaptic pruning

Answer 6

reducing the number of neural connections

happens because cells do not receive the “survival factor” signals from other neighbouring cells. The ones not getting enough stimulation wither

this allows the brain to fine tune and specialize in specific environments. allows it to be sculpted according to experience

earliest in sensory and cortical regions

latest in frontal cortex (not complete until late adolescence)

Question 7

synaptic overproduction

Answer 7

allows the brain initially to have maximal capacity to respond to the environment

Question 8

myelination

Answer 8

glial cells provide myelin sheath

which matter increases and grey matter

a longer process that varies by region of the nervous system

myelination of basic sensory and motor systems: within 1st year after birth

myelination of integrative systems occurs later

medulla and spinal cord and myelinated early on in life - support basic functions

Question 9

myelination in childhood and teenage years

Answer 9

relative amount of white matter increases and gray matter decreases

brain volume generally larger in boys for both grey and white matter

Question 10

dual systems model

Answer 10

when no reward is involved, adolescents show adult-like logical reasoning skills

when strong emotional incentives are present, adolescents make riskier choices

activity in the nucleus accumbens (ventral striatum) increases in adolescents when anticipating of receiving a reward. Combination of this and the still developing prefrontal cortex leads to riskier behaviours. decreases in adulthood b/c prefrontal cortex matures and has better control over the limbic system.

Question 11

experience-expectant systems

Answer 11

develop in response to experiences are common to nearly all members of that species
ie/ patterened light, presence of caregiver, exposure to language

neural systems develop normally when the expected input is received, but are seriously affected when the expected experience is absent

Question 12

experience-dependent systems

Answer 12

develop in response to experiences that are not universal, but vary across people based on their unique experiences

ie/ musical training early life, learning to juggle, learning to ride a bike

we are likely to develop different motor and musical skills

Question 13

environmental enrichment and deprivation

Answer 13

many studies have been conducted in other species

control condition: rat alone in a small plastic cage
enriched condition: large area with varied spatial arrangement, toys and social interaction with other rats

enriched environments positively influence synaptic connectivity in early development and adulthood

changes persist even when the animals are later removed from the enriched setting

Question 14

bucharest early intervention project

Answer 14

orphaned children in state care randomly chosen to receive
1. continued care in state run orphanage (little social or intellectual stimulation)
2. placement with a highly trained family

those placed in foster car before two years of age showed improvements in intelligence and normalized EEG activity

effects of environmental deprivation during critical developmental windows in orphaned Romanian children

Question 15

sensitive periods

Answer 15

organism is particularly sensitive to certain external stimuli during a specific developmental period
(though certain effects can influence over a lifetime)

• allows for locking in influence

visual system: exposure to visual input in both eyes needed in first months of life to develop normal binocular vision

language: learning a new language becomes more difficult in adulthood

deprivation of social contract during this time can effect development

Question 16

developmental disabilities

Answer 16

conditions that typically make their first appearances during childhood

represents a departure from normal developmental path

lots of unknown causes

Question 17

intellectual disability

Answer 17

mental retardation

can be caused by genetic disorders, infections, toxins and oxygen deprivation

classified based on severity

Question 18

genetic disorders

Answer 18

some genetic disorders can cause intellectual disability

ie/ down syndrome

Question 19

down syndrome

Answer 19

most common genetic cause of intellectual disability

severve disability

associated with IQs in the lowest 2 percent

occurs in 1 in 700-800 births

caused by trisomy 21 (three copies of 21st chromosome results in down syndrome)

characterized by morphology of face and body (aids early diagnosis)

deficits in language and verbal memory - sometimes better functioning in visuospatial and social tasks

Question 20

trisomy 21

Answer 20

a condition where the 21st pair of chromosomes contain 3 chromosomes instead of 2

Question 21

fetal alcohol spectrum disorder

Answer 21

intellectual disabilities cause by mother’s alcohol consumption during pregnancy

continuum of severity impacted by exposure, this is most sever

Question 22

symptoms of fetal alcohol syndrome

Answer 22

hyperactivity, poor impulse control, social/emotional difficulties, difficulties learning and memory, executive dysfunction

slowed physical growth and abnormalities of the face and cranium

Question 23

changes in brain structure for fetal alcohol syndrome

Answer 23

reductions in gray matter volume throughout the brain

altered trajectory of white matter development throughout childhood and adolescence, especially connections between the frontal lobes with other brain regions

Question 24

learning disability

Answer 24

when only one cognitive domain is affected

Question 25

dyslexia

Answer 25

sometimes referred to as a specific reading disability a specific inability to learn to read at an age-appropriate level, despite adequate opportunity, training and intelligence characterized by a deficit in phonological understanding: linking a particular letter to a particular sound, being able to decode words into their constituent phonemes (misreading house for hose) perceptual mechanisms needed to acquire phonological awareness may be deficient poor communication between sensory regions and higher level regions involved in language

Question 26

autism spectrum disorder

Answer 26

diagnosis involves two main characteristics: 1. impairment in social interations across a range of contexts (non-verbal communication, reciprocity, developmental of social relationships) 2. restrictive or repetitive activities or interests (inc.motor actions) symptoms must be present in early development - most diagnoses made around the age of three - behavioural signs are often evident earlier many potential causes: genetics, infectious diseases, birth injuries, metabolic diseases, and environmental factors no evidence that vaccines cause or contribute to autism enlarged overall brain volume

Question 27

cortical thickness in brain

Answer 27

increased cortical thickness early in development decreased thickness in later years of development varies across brain regions

Question 28

white matter development in autisim

Answer 28

increased white matter early in development later: slower rate of myelination, falling behind peers in white-matter development

Question 29

attention-deficit/ hyperactivity disorder (ADHD)

Answer 29

8-10 percent of children in U.S boys more commonly diagnosed compared to the average child of the same age, a child with ADHD is either inattentive, hyperactive/impulsive or both (compared to the average child at that age) symptoms must be "inconsistent with developmental level" child must have a clinically significant impairment that interferes with adaptive functioning in more than one setting

Question 30

many hyptheses of ADHD

Answer 30

suppressed frontal lobe activity - deficit in inhibitory control - inability to inhibit inappropriate responses assess using stop signal task - deficit in motivational processes, such as delay adversion dysregulation of default mode network disruption of attentional filtering by thalamus disruption of right hemisphere function underproduction of dopamine - unwillingness to wait for rewards

Question 31

ADHD and dopamine

Answer 31

dopamine system is strongly implicated dopaminergic cells project both to basal ganglia and prefrontal cortex, regions, regions whose activity is altered by ADHD - drugs used to treat ADHD influence the dopamine system - genes implicated in ADHD are generally genes that influence dopaminergic neurotransmission

Question 32

treatment of ADHD

Answer 32

effects of methylphenidate (Ritalin) on attention networks also given behavioural modification strategies

Question 33

do children outgrow specific learning disabilities

Answer 33

some learning disabilities appear to become less severe with age (maturation hypothesis) however, difficulties may manifest in a different form and manner as an individual matures disabilities persist, but effective compensation mechanisms are developed people with learning disabilities have successful personal and professional lives, often by emphasizing other cognitive strengths and/or utilizing compensation mechanisms

Question 34

brain plasticity in adulthood

Answer 34

brain is not fixed in adulthood - brains can respond to environmental input increased experience can change brains representation of info training can increase cortical representations loss of input of a certain kind can cause representations to wither away brain maps are not set in stone - maintained through continual input new neurons generated just not at the rate of the perinatal period

Question 35

plasticity in amputation

Answer 35

the map in somatosensory cortex is reorganized; territory previously corresponding to lost part is now responsive to a neighbouring part of the body somatosensory cortex can reorganize after amputation amputee continue to feel sensations in their limbs even though they know it is missing

Question 36

reorganization of function

Answer 36

"maps" in sensory cortex are maintained only though continual sensory input - when input changes systemically, the map changes some people continue to perceive sensations that can be distracting and painful phantom limb sensations may occur when cells used to code for the lost limb are now being stimulated by new input from a different body location

Question 37

cross model plasticity

Answer 37

cortex normally dedicated for one purpose can be rededicated to an entirely different purpose ie. visual cortex in people blind from birth no visual input - but is activated by braille reading, other tactile stimulation, and some auditory and verbal tasks indicates that the visual cortex can reorganize to respond to nonvisual information in congenitally blind people - reorganizes "visual" info for other functions

Question 38

necrosis

Answer 38

cells begin to die at site of lesions affects nurons and glia that insulate neurons

Question 39

transneuronal degeration

Answer 39

cells loss can extend to more distal neurons if cells do not recieve optimal stimulations and chemical factors can occur across more than one synapse

Question 40

edema

Answer 40

swelling which increase pressure within skull (can be life threatening)

Question 41

cellular level changes that aid recovery

Answer 41

generation of new cells: neurogenesis and gliogenesis angiogenesis: new blood vessels grow and reestablish blood supply to damaged region axonal sprouting connecting regions that has not previously been connected - new synapses

Question 42

what doees damage to a discrete region of the brain region affects

Answer 42

cells in that immediate area, surrounding tissue and more distant brain tissue when the damaged area within the primary motor cortex is relatively large, there may not be enough intact tissue in that hemisphere to support recovery of function. in such a case, function maybe partly taken over by the parallel region of the opposite hemisphere

Question 43

damage to primary motor cortex (M1)

Answer 43

affect primary somatosensory cortex (S1) and motor cortex (PM), as well as connecting pathways

Question 44

true recovery

Answer 44

the original function is restored may be limited to the first few months

Question 45

compensation

Answer 45

the person learns a work-around, to do a task in a new way strategies can be implemented at any time

Question 46

specific training programs

Answer 46

promotes recovery physical therapy for motor difficulties following stroke emphasis n repeated use of limb or speech

Question 47

stimulation methods

Answer 47

promotes recovery TMS tDCS stimulate damaged hemisphere inhibit contralateral hemisphere to reduce competition

Question 48

kennard principal

Answer 48

not as many consquences in children the idea that the earlier in life damage is sustained, the better the recovery damaged to you brain still has consequences: early left-hemisphere damage: no aphasia, but still deficits in phonology, syntax, and linguistic semantics early right-hemisphere damage: difficulties in spatial cognition, analogous to those of right-hemisphere-damaged adult some evidence say early-occurring brain damafe may actually produce worse long term consequences than later occuring damage - sensitive during development - consequences of an adult brain are usually obvious, but a childhood-acquired injury may take years to see full recovery

Question 49

crowding hypothesis

Answer 49

intact areas of the child's brain must carry out normal functions plus functions that the damaged area would have implemented

Question 50

cognitive changes with aging

Answer 50

general decline - all abilities decline with age - results show a general reduction in mental resources or a general slowing in processing speed reality: some abilities decline more with age than others: - decline with fluid intelligence but not crystallized intelligences -emotional regulation improves - cognitive functions within frontal and temporal regions shows greater decline with afge a lot of older people remember what happened early on in life

Question 51

neural changes with aging

Answer 51

changes in brain volume different brain regions show different trajectories of growth and decline over the lifespan some show general decline in volume over lifespan some show curvilinear pattern last in first out: last to develop in childhood, soonest to decline at the end of the lifespan

Question 52

slow the effects of aging

Answer 52

can never completely aerobic exercise: - multiple benefits - produces a greater proliferation of blood vessels to brain, resulting in enhanced oxygen supply remaining intellectually active - mentally stimulating environment produces an elaboration of dendritic trees, allowing more numerous and varied synaptic connections - will continue to work if you continue to use it - use if or lose it