Cognition and the Developing Brain

Question 1

development time for a human child compared to an animal infant

Answer 1

Children have a very long development and need care for a long time, this is very different than most other mammals. You have to wait at least a year for children to walk which is a really long time compared to a horse - longer period of vulnerability for human infants

Question 2

what are the advantages of having a long development time for children

Answer 2

advantage to the immature cognition - motor development is limited = less wandering may help with safety

limited visual acuity = help focus on the most salient features they need to perceive in the env, simplify the info to build base knowledge.

overestimating their abilities keeps them trying until they learn

Question 3

what is the most striking feature of brain development in the first ten years of life

Answer 3

the most striking thing is there is a lot of change in even the volume of the brain between the 1st week and the first year. it also becomes whiter and whiter. between 2 and 10 years the change is so much smaller than between 1 week and 2 years.

Question 4

at what size is the brain at preschool age

Answer 4

90% of adult size by preschool age

Question 5

what are the structural changes in grey matter at the level of the cortex
describe the direction of development

Answer 5

neuron bodies, dendrites, axon terminals.

• includes synapses.
• inverted U shaped trajectory
• from back to front, lower to higher cognitive functions

Question 6

what is the process called that creates synapses

Answer 6

synaptogenesis
this increases very sharply after birth
way more synapses in the infant brain than adult brain
does not happen at the same time for everywhere in the brain e.g sensorimotor cortex earlier than prefrontal

Question 7

what follows synaptogenesis

Answer 7

pruning - way more synapses in the infant brain than in the adult brain but these will be neither strengthened nor weakened and cancel out each other. therefore functioning is not that efficient yet. over time these will be pruned due to interactions, learning and experience. some get stronger (those that are helpful) but those that get weaker are less helpful and may eventually be pruned completely

Question 8

what does it mean that there is asynchrony across brain regions

which areas mature before others and why

Answer 8

somatosensory and visual cortices mature before higher order association cortices. this is because the sensorimotor is for perception of things in env but association is for planning, not needed until later in life. it also builds on the development of other skills first.
somatosensory and visual cortices mature before higher-order association cortices

Question 9

how is the development of the childhood brain compared to the alzheimers

Answer 9

development of the childhood brain is the opposite of alzheimers progression. the red on the AZ brain is plaque and knots that represent a protein that interferes with the function of the brain. these develop first in the association cortex and then eventually affect the sensorimotor cortex. regions of the brain that support higher order cog functions take the longest to develop but are the first to start declining in AZ but also in normal aging.

Question 10

which areas are more robust

Answer 10

areas that develop earlier are more robust

Question 11

how does cortical thickness relate to intelligence

Answer 11

if you keep the ability to make new connections for longer you will adapt better to the environment. this leads to higher intelligence. thinning is slower in higher intelligence.

Question 12

how do you measure intelligence in relation to cortical thinning

Answer 12

usually use the WESCHLER for intelligence. use g for intelligence. this is a standardised test that help you measure different cognitive abilities.

Question 12

how does the influence of genes and env change over time on intelligence

Answer 12

using MZ twins you can investigate it, as time goes on in high IQ twins the genes become more important than env. in low IQ twins the same pattern but the genes become important sooner than high IQ

Question 13

what are the changes in white matter

what is the role of myelin and what are white matter tracts made of

Answer 13

Glia and myelinated axons (white-matter tracts) white matter is mostly myelin.
Myelin is the cells in the brain whose role is to develop layers of fat along the axons which insulates the neurons so the signals can propagate faster. White matter tracts are made of the axons of projection neurons (these project their axon very far from one part of the brain to another)

Question 14

how do you measure myelin

what is the range of possible outcomes

Answer 14

Diffusion tensor imaging (DTI)

• Water molecules diffuse in all directions in gray matter and cerebrospinal fluid (isotropic diffusion), and along axon bundles as myelin sheath impedes diffusion in other directions
• Fractional anisotropy (FA) measures how directional diffusion is within a voxel (0 = isotropic, no white matter; 1=anisotropic, white matter)

isotropic = molecules diffuse in all directions no variation = low integrity of myelin.
anisotropic = a lot of myelin the integrity of myelin is high.

Question 15

how long does myelin develop

Answer 15

continues developing after 5 years, may even cont to over 50

Question 16

what are the categories that myelinate at different times from gestation to 30 years old

Answer 16

gestation to first year - sensory systems (optic nerve, initial stages of sensory processing)
gestation to years one to 2 - cerebellum (motor system)
first year to 1-2 years - major motor neuron tracts (motor systems)
first year to 5 years - connections between midbrain and cortex (integrative systems)
first year to up to 30 years - cortical association areas (integrative system)

Question 17

what is myelin exactly
what is greater myelin associated with

Answer 17

electrically insulating layer of fat wrapped around neuronal axons
speeds up neuronal signal propagation = cognitive processing speed (time taken to perform mental operations)

greater myelin = faster processing speed

Question 18

what impacts does faster processing speed have

Answer 18

quantitative increases -
greater amount of info absorbed in time interval,
greater amount of info activated in working memory e.g faster rehearsal
mental operations faster

qualitative changes -
less time for info to decay, larger number of neural networks can be co activated increasing the complexity of mental operations that can be performed

Question 19

what is the developmental cascade model

Answer 19

it considers the processing speed as the most important driving factor in development and goes as follows

increasing age -> greater myelin -> increase in processing speed -> increase in working memory -> increase in fluid intelligence

Question 20

what is the lifespan evidence for a developmental cascade

Answer 20

speed of processing, attention, spatial working memory, verbal functioning, exec func all increase in test performance from age 0 to 20 then decreases - inverted u shape dev

Question 21

how are age IFOF and testable skills related

Answer 21

age correlated to IFOF 0.294
IFOF correlated to speed of processing 0.168 and to visual learning 0.287

speed of processing related to exec, attention, spatial wm, verbal and visual learning

because they are pos not neg = connection means a higher result.
myelination = greater cog outcomes

Question 22

how might we be able to promote better myelination outcomes

Answer 22

through breastfeeding
rich complement of long hcain fatty acid (DHA, AA) in breast milk. implicated in healthy neuronal growth, repair and myelination

breastfeeding associated with greater myelin including frontal regions
there is a duration effect (longer breastfeeding associated with brain volume outcome - more days mroe volume)

Question 23

what is breastfeeding linked to in terms of outcomes and is the link clear

Answer 23

cog benefits such as motor skills, reading, attention, intelligence, problem solving, cognitive control

link much weaker after controlling for factors such as breastfeeders tend to be richer and support cognitive developmetnt through education

Question 24

how can we summarise white matter changes across development

Answer 24

glia and myelinated axons increases progressively throughout childhood and beyond lower to higher functions faster local and distal connections faster processing speeds

Question 25

what are the general principles of brain development for the most complex and flexible cognitive abilities

Answer 25

most complex and flexible cognitive abilities take the longest to develop and are supported by the most plastic regions, and are the most sensitive to env influences and are the first to decline in ageing

Question 26

how do simpler abilities develop in comparison to more complex ones

Answer 26

mature earlier supported by regions that mature earlier too less sensitive to env influences more robust

Question 27

what is the maturational account

Answer 27

same brain regions are used for cognitive abilities but as people mature more regions are being added maturation within each region supports increasing performance this is deterministic epigenesis

Question 28

what is deterministic epigenesis

Answer 28

genes -> brain -> cognition

Question 29

what is an example of the maturational account

Answer 29

before successful working memory performance there is immature activation of DLPFC and superior parietal after successful wm performance there is mature activation of DLPFC and SUPPAR

Question 30

what is the skill learning account

Answer 30

cognitive development = same as learning a new skill, cog control needed for learning the new skill learnt it you optimise the processing, the prefrontal cortex isnt supporting the skills anymore it is in the posterior regions. initial brain regions needed to develop are not the same as those that support them later on when the children become better at those functions.

Question 31

describe the steps in skill learning account

Answer 31

Some regions initially involved in ability acquisition, once learnt the ability is supported by other (more specialised regions) this is a dynamic changing brain and is cognition mapping same dynamic in development as skill learning role of practice

Question 32

give an example of the skill learning account

Answer 32

before successful wm performance reliance on lower level system after successful wm performance reliance on higher level system

Question 33

what is the interactive specialisation account how do we get changing inter regional patterns

Answer 33

shift from initially diffuse cortical regions with poorly defined/broad functions to progressively more specialised focal regions competitive specialisation through interactions with other regions (networks) = changing inter-regional patterns dynamic/changing brain/ cognition mapping probabilistic epigenesis (circular causality)

Question 34

what is probabilistic epigenesis

Answer 34

cognition = genes and environment

Question 35

what is an assumption for the interactive specialisation account

Answer 35

with age you see a more focal pattern of brain activity this can be shown with the visuospatial working memory tasks. when you have the cross it disappears and you look at the cue. the activity in children is more diffuse especially compared to the adults

Question 36

describe the study for progressive specialisation of numbers and letters

Answer 36

processing of numbers vs letters used EEG looked at posterior N1 which is an ERP that happens quickly after the ppt saw the stimuli looked at letters numbers and false prompts

Question 37

describe the results for the study for progressive specialisation of numbers and letters

Answer 37

diff age groups electrodes on the right side of EEG show different colours for the wave forms. N1 is negative so lower down = more activation in children no specialisation of letters and numbers - voxels all same colour in 15 yo you see differences

Question 38

define regressive specialisation how does progressive and regressive specialisation relate to face processing

Answer 38

brain area that used to support cognitive function but no longer does = regressive specialisation areas that children use for face recognitiion no longer used in adults e.g L angular

Question 39

what are structural networks

Answer 39

structural connectivity brain areas with important axonal projections among them (through white matter tracts) said to be wired togetherw

Question 40

what are functional networks

Answer 40

functional connectivity brain areas with tightly coupled activity (activate/work together)

Question 41

how are functional networks examined at rest

Answer 41

covariation in spontaneous low frequency (<0.1Hz) Bold signal fluctuations between brain regions across different brain areas which reflect long standing history of co activation on tasks

Question 42

how are functional networks examined on task

Answer 42

covariation in BOLD signal during the task

Question 43

describe the modelling of a module

Answer 43

circle = node = part of the brain line = edge = connections between nodes hub = circle that connects two networks together in this example it is red and also the middle circles in the module - where lots of connections join

Question 44

what is graph theory

Answer 44

a statistical approach to looking at connectivity and uses the nodes edges etc.

Question 45

are structural and functional networks similar do they predict each other and why

Answer 45

there are lots of overlaps between structural and functional networks they are established early in life but strengthen through late adolescence structural connectivity predicts concurrent functional activity struc connectivity predicts subsequent change in functional connectivity this is the effect of experience on myelin

Question 46

what are the mechanisms of change in network connections

Answer 46

segregation - weakening of local (short range) cross network connections integration - strengthening of distal (long range) within network connections - strengthening of cross network connections between hubs

Question 47

do we want segregation

Answer 47

long range connections usually connect more parts that are far away but are part of the same network. want networks to become more and more segregated so the way they function becomes more and more efficient still however need cross network connections which tend to be strenghtened as well but for specific parts

Question 48

how does segregation and integration of structural networks change over age in relation to statistical graphing terms

Answer 48

with age non hub edges decrease across networks hub edges (connections) increase both within and across networks

Question 49

what does modular segregation lead to with age in the fp network and the default mode network

Answer 49

modular segregation of frontoparietal control network -> greater cognitive control modular segregation of default mode network -> greater social cognition

Question 50

what are the key roles of network hubs

Answer 50

hubs are key nodes receive a lot of connections and integrate disparate neural systems through long range connections mediate large fractions of signal traffic both within and between networks hub locations in adults - association cortices (frontal parietal and medial) subcortical structures - basal ganglia thalamus

Question 51

what are the changes in centrality for structural network hubs

Answer 51

rich club organisation in place from birth - a lot of signals travelling between the hubs centrality changes with age sensorimotor and temporal in infancy; language related areas (superior/middle temporal gyrus, angular gyrus) in childhood; frontal cortex in adolescence

Question 52

what are the changes in network hubs in relation to functional hubs

Answer 52

greater functional connectivity among hubs both within and across networks shift from primary sensory and motor areas to more distributed patterns including association cortices and subcortical areas through gradual maturation of long range axonal projections

Question 53

what is the hypothesis of hierarchical functional organisation along sensorimotor association axis

Answer 53

in infancy there is a lot of segregation of the sensorimotor networks and association networks ensuring efficiency of this processing then in middle childhood the networks in the middle of the hierarchy tend to establish a lot of connections with other networks through hubs then the networks at the top during adulthood show greater segregation allows for an efficient way for the brain to function allows specialised functioning at the same time while the middle of the hierarchy has greater connection with other networks and allow communication and orchestration of these processes

Question 54

does the body constrain brain cognition behaviour

Answer 54

brain drives behaviour (generate) motor activity leads to sensory inputs perturb leads to influence on brain bodily changes modify sensory inputs, possible actions, social interactions (able to crawl = more stuff, able to walk more stuff again)

Question 55

can changes in body constrains cause a developmental cascade across domains

Answer 55

child able to sit and manipulate objects (motor skill) receive different verbal output from the env and people are likely to offer the child to engage in a new object new linguistic input which will manipulate objects in an original way = develop motor skills again official cascade: motor skill -> communication and language -> caregiver input and env

Question 56

what is the experiment looking at exploration %

Answer 56

3 month old (cant pick stuff up) exp group sticky mittens so can pick stuff up = enrichment session allowed them to practice manipulating objects before they otherwise would - other group no mittens no exploration after enrichment were allowed to explore other toys test trial mitten group spent more time exploring than control = time spent using mittens boosted the cognitive capability of exploration

Question 57

why is functioning inefficient related to synapses in infant brain

Answer 57

will be neither strengthened nor weakened and cancel out each other. therefore functioning is not that efficient yet.

Question 58

which learning account is deterministic epigenesis and which is probabilistic

Answer 58

deterministic = maturational probabilistic = interactive specialisation