Cognition and the Developing Brain Flashcards
development time for a human child compared to an animal infant
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
what are the advantages of having a long development time for children
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
what is the most striking feature of brain development in the first ten years of life
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.
at what size is the brain at preschool age
90% of adult size by preschool age
what are the structural changes in grey matter at the level of the cortex
describe the direction of development
neuron bodies, dendrites, axon terminals.
- includes synapses.
- inverted U shaped trajectory
- from back to front, lower to higher cognitive functions
what is the process called that creates synapses
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
what follows synaptogenesis
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
what does it mean that there is asynchrony across brain regions
which areas mature before others and why
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
how is the development of the childhood brain compared to the alzheimers
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.
which areas are more robust
areas that develop earlier are more robust
how does cortical thickness relate to intelligence
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.
how do you measure intelligence in relation to cortical thinning
usually use the WESCHLER for intelligence. use g for intelligence. this is a standardised test that help you measure different cognitive abilities.
how does the influence of genes and env change over time on intelligence
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
what are the changes in white matter
what is the role of myelin and what are white matter tracts made of
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)
how do you measure myelin
what is the range of possible outcomes
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.
how long does myelin develop
continues developing after 5 years, may even cont to over 50
what are the categories that myelinate at different times from gestation to 30 years old
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)
what is myelin exactly
what is greater myelin associated with
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
what impacts does faster processing speed have
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
what is the developmental cascade model
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
what is the lifespan evidence for a developmental cascade
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
how are age IFOF and testable skills related
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
how might we be able to promote better myelination outcomes
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)
what is breastfeeding linked to in terms of outcomes and is the link clear
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
how can we summarise white matter changes across development
glia and myelinated axons
increases progressively throughout childhood and beyond
lower to higher functions
faster local and distal connections
faster processing speeds
what are the general principles of brain development for the
most complex and flexible cognitive abilities
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
how do simpler abilities develop in comparison to more complex ones
mature earlier
supported by regions that mature earlier too
less sensitive to env influences
more robust
what is the maturational account
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
what is deterministic epigenesis
genes -> brain -> cognition
what is an example of the maturational account
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
what is the skill learning account
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.
describe the steps in skill learning account
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
give an example of the skill learning account
before successful wm performance reliance on lower level system
after successful wm performance reliance on higher level system
what is the interactive specialisation account
how do we get changing inter regional patterns
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)
what is probabilistic epigenesis
cognition = genes and environment
what is an assumption for the interactive specialisation account
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
describe the study for progressive specialisation of numbers and letters
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
describe the results for the study for progressive specialisation of numbers and letters
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
define regressive specialisation
how does progressive and regressive specialisation relate to face processing
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
what are structural networks
structural connectivity
brain areas with important axonal projections among them (through white matter tracts) said to be wired togetherw
what are functional networks
functional connectivity brain areas with tightly coupled activity (activate/work together)
how are functional networks examined at rest
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
how are functional networks examined on task
covariation in BOLD signal during the task
describe the modelling of a module
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
what is graph theory
a statistical approach to looking at connectivity and uses the nodes edges etc.
are structural and functional networks similar
do they predict each other and why
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
what are the mechanisms of change in network connections
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
do we want segregation
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
how does segregation and integration of structural networks change over age in relation to statistical graphing terms
with age non hub edges decrease across networks
hub edges (connections) increase both within and across networks
what does modular segregation lead to with age in the fp network and the default mode network
modular segregation of frontoparietal control network -> greater cognitive control
modular segregation of default mode network -> greater social cognition
what are the key roles of network hubs
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
what are the changes in centrality for structural network hubs
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
what are the changes in network hubs in relation to functional hubs
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
what is the hypothesis of hierarchical functional organisation along sensorimotor association axis
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
does the body constrain brain cognition behaviour
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)
can changes in body constrains cause a developmental cascade across domains
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
what is the experiment looking at exploration %
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
why is functioning inefficient related to synapses in infant brain
will be neither strengthened nor weakened and cancel out each other. therefore functioning is not that efficient yet.
which learning account is deterministic epigenesis and which is probabilistic
deterministic = maturational
probabilistic = interactive specialisation
