The Developing Brain: From Theory to Neuroimaging and Back Flashcards Preview

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Flashcards in The Developing Brain: From Theory to Neuroimaging and Back Deck (23)
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1

How are developmental psychology and neuroscience segregated?

  • there is a gap between knowledge of brain development and cognitive development of humans
  1. developmental neuroimaging studies tend to be data-driven instead of theory driven
    • priority is to find differential maturational trajectories of certain structures/functions rather than comfirming/rejecting predictions from developmental theories
  2. developmental psychologists tend to expalin functional changes (e.g. wm) in classic stage-wise terms, ignoring functions relating these things to brain maturation

2

What were some of the early edndeavors trying to combine cognitive developmental psychology with neuroscience?

  • initial attempts focused on brain size:
    1. Epstein's phrenoblysis hypothesis (phreno = skull, blysis = welling up of matter)
      • findings suggested that the brain grows in spurts with peak growth rates at ages 6, 8, 10, 12, 14 and 17
      • pattern of peaks and troughs was relatd to piagetian theory (stages), preceding and preparing stage transitions
      • much methodological criticism
  • others focused on the brain's electricial activity:
    1. Matousek and Petersén (1973) found developmental changes in spectral power, periods of rapid growth, alternating with periods of slow growth
    2. Thatcher (1994) found EEG coherence, a spectral measure indexing functional coupling of neural generators with growth spurts cycles in cortical organisations, transition phases at ages 6 and 10
  • these findings were integrated in neo-Piagetian views. hypothesis that stage-wise cognitive development is driven by iterative and sequential brain-growth cycles still needs to be confirmed

3

Early developmental neuroscience depended upon post-mortem studies. What did they find?

  • they found that the size of the brain increases until age 9 or 10 and then size and weight do not change much untile scenescence
  • they found two main changes ocurring in the developing brain:
    1. expansion of myeline layer around axons of developing neurons continuing until adolescence (especially frontal regions)
    2. synaptic density (number of synapses) increase strongly in early post-natal development, followed by pruning during maturation

4

Diffusion tensor imaging (DTI) shows how white and grey matter changes occur during growing up:

  1. white matter density and myelination seems to increase continuously during childhood.
    • it also seems wide-spread across the brain even though some studiees suggest regional specificity
  2. grey matter appears to follow an inverted U-shape pattern of region specific development
    • there are progressive and regressive changes
    • in prefrontal cortex, parietal cortex and superior temporal cortex grey matter peaks around puberty
    • in temporal cortex it appears to peak around age 17

5

What are some limitations of MRI studies?

  • data is correlative,
  • commonly reversed inferences are made

6

What do information-processing theories emphasise and what supporting evidence has been found?

  • they emphasise that biologically-based growth of internal control, self-regulation, working memory and automatisation allows children to progressively increase processing limits
    1. e.g. working memory capacity has been explainedas an age related increase in processing spacee, so absolute capacity does not change but capacity functions more efficiently with advancing age
    2. early in development children supposed rely more on working memory storage but the process is less efficient
    3. across development children increase processing ability, so necessary storage space decreases, this may be influenced by a general increase in processing speed

7

What were some findings that challenge Piaget's stage-theory?

  • may have underestimated young childrens cognitive abilities via too complex task designs
    1. e.g. evidence suggest that pre-operational toddlers would pass a false-belief task if it is designed apropriately
    2. or, 9-month old infants exhibit predictive motor activation when perceiving grasping movements

8

What are the four Piagetian stages?

What are they assumed to be propelled by?

  • The four stages:

    • Sensorimotor stage: birth to 2 years

    • Preoperational stage: ages 2 to 7

    • Concrete operational stage: ages 7 to 11

    • Formal operational stage: ages 12 and up

  • assumed to be propelled by dynamic processes of assimilation and accomodoation
    • may be hinting to the sensitive periods of brain development that are charcterised through synaptogenesis and synaptic pruning

9

Piaget suggested that a child cannot reach a new stage before mastering the old one. Is there neuroscientific evidence for this?

  • similarities with the idea of hierarchical development of conscious control levels
    • synaptic density (DTI) studies suggest that changes in grey matter develop at differet rates for different brain regions
    • the change in grey matter in a higher-order brain region would not contribute to cognitive functioning unless grey-matter changes in supporting regions were already completed
    • unclear if functional change is gradual or suddenly

10

One information-processing theory is referred to as the levels of consciousness theory. What is it postulating?

  • that development of consciousness goes via hierarchical functional system changes:
    • young children can mast a level (e.g. keeping rules active in mind) but not yet another (e.g. flexibly switching between competing rules)
    • once the highest level is reaached children can do the most complex tasks (age-related improvements)

11

Theories postulate that for more complex tasks two or more brain systems may work closely together. E.g. Case's conceptualisatin of working memory development:

(What alternative explanation comes from the levels-of-consciousness theory?)

  • Case's concept for working memory is that there needs to be one system for storage of information and one system for processing of information (EF of stored information)
    • relative contributions of these system change
  • alternatively the conscious processing account says that EF reflective consciousness is dependent on maturation of additional brain areas in prefronatl cortex (PFC)

12

What findings support the idea that processing capacity increases over a childs development? (fMRI and DTI)

  • fMRI studies showed that increasingability to maintain information between age 8 and 12 coincided with increased activation in PFC and lateral PFC
  • DTI data revealed increased fractional anisotropy in froto-parietal white matter (suggestive of increased strength of anatomical connectivity) correlated with BOLD activation in lateral PFC and with visuolspatial working memory capacity

13

Some early behavioural research suggest that working memory depends on the interplay between storage capacity and manipulation. What is the evidence supporting this?

  • studies that differetiated between pure maintenance and manipulation of information
    • they found evidence for different neual systems supporting this system:
      1. ventrolateral PFC was only active for maintenance trials
      2. dorsolateral PFC would be additionally recruited if information needed manipulation
        • the finding of slower dorsolateral development could be indicative of delayed processing development
        • hence, possibly this suggests that storage capacity can remain stable whereas processing capacity may independently increase with advancing age (indicated by increased dorsolateral PCD activation when demands increase)

14

Some studies focused on age related qualitative differences in brain activation while perfroming the same task. (In contrast to those that focus on icreases and decreases in activation of certain brain areas)

  •  8-12-year olds and 13-17-olds show a qualitatively different activation pattern when performing a working memory maintenance task
    • 8-12-year-olds did not activate lateral PFC and parietal cortex like adults do, instead they relied on ventromedial PFC
    • 13-17-year olds did recruit the lateral PFC just like adults, but to a lesser degree
    • results were interpreted as a shift in storage or processing capacity
    • also supports information processing theories by showing thta the neurological network underlying abstract thought is still imporving across adolescence

15

Johnson established a biological framework for the development of early attention systems.

What are its advantages and what are three possible trajectories?

  • this can relate cognitive development to brain maturation trajectories in a testable fashion
    • also allows for mapping of between cognitive theories and neulogical trajectories/findings
  • The three possible routes of neuroanatomical development:
    1. maturational progress (maturation of additional brain areas
    2. interactive specialisation (changes in interactions between brain areas)
    3. skill learning (patterns of activation of cortical regions change during acquisition of skills)
  • theory was developed for first two post-natal years but could be applied to more advanced levels of cognitive functioning (e.g. working memory)

16

If Johnsons neuroanatomical development and trajectories would be applied to the issue of working memory, which of the trajectories does the evidence point to?

  •  multiple pathways including ventrolateral PFC, dorsolateral PFC, seuperior parietal cortex
    • e.g. additional recruitment of dorsolateral PFC in working memory could be interpreted
      1. via the maturational account (as predicted by theories of execuitive function development)
      2. or interactive specialisation account (as predicted by classic information-processing theoriies)
      3. however, qualitative differences in brain activatioon between children and adults could hint to the skill learning account
    • even though all accounts are possible Johnson argues in favour of interactive specialisation

17

According to Crone and Ridderinkhof, a main reason why neuroimaging evidence is not useful in cofirming or rejecting developmental theories its its focus on one age groups. Explain.

  • information-processing theory assumes that most developmental changes occur between 7 and 12 years old, hence most neurological studies focuses on this age group
    • however, its unclear if findings result mainly from the youngest, or maybe from the whole child-group
    • studies should select age-grou carefully based on predictions of developmental theories

18

A second difficulty for testing developmental theories with neuroimaging data are poor correlations between behavioural and brain effect sizes.

Why is it problematic?

  • correlations between brain and behaviour effects sizes are usually modest
    • however, poor if only one age group is included
    • so it difficult to distinguish effects of maturation from individual performance differences (also because perfromance is often correlated with maturational change)
  • sometimes poor brain-behaviour correlations are associated with small effect sizes in the brain or behaviour measure
  • combination of functional development and structural development indices (e.g. developmental DTI studies) is necessary to expose the extent to which mental growth corresponds with brain (white-matter) growth

19

Age seems to be a problematic predictor of test-retest effects or longitudinal changes. Why is that and why is it problematic for the testing of developmental theories?

  • its problematic, because not everyone develops with the same speed at the same age, so individuals may have a different maturation trajectories even if they have the same age, depending on individual (e.g. genetic) and external reasons (environment)
  • a longitudinal study (3 year follow up, 8 - 28 year olds) found that a better predictor than age (predicting brain changes) was perfromance. Those that had the biggest perfromance changes also had the biggest brain changes

20

Training and intervention studies seem to give hints against a maturational account. Explain.

  • perfromace can increase with training and because performance seems to be the best predictor for brain activation, activation should increase with training too
    • demonstrated that in 11-12 year olds, lateral PFC activation could be increased with extensive working memory training
    • findings suggest that developmental differences in brain activation are not fixed and can be modified
      • does not fit with a purely maturational account, skill learning account seems more fitting

21

  Crone's and Riddernkshof's suggestions for neuroimaging research based on developmental theory:

Suggested guidelines for neuroimaging research:

  1. Selection of age-groups should be theory-driven
  2. Compute brain-behaviour correlations and be aware of differences in effect sizes
  3. maturation and change can only be examined using longitudinal designs
  4. training and intervention studies can demonstrate the malleability of cognitive functions and underlying neural mechanisms
  5. compensatory brain activation should be interpreted with caution
  6. differential brain activation can be caused by strategy differences

22

Why is it problematic that most control functions have been studied in isolation?

  • observation is often that certain brain areas that are activated in adults (for doing a task) are not activated (or not to the same degree) in children
    • however often times other additional brain areas are activated in children, what are they for?
      • they could be compensatory (as e.g. that 15 year olds additionally recruit the hippocampus for memory tasks, in contrast with adults)
      • we can only examine them post-hoc which leads to reverse inference, caution (e.g. if children use for a task more the left hemisphere, authors conclude that they use a more verbally guided approach because the left hemisphere in adults tend to be languague focused.

23

Keep in mind that differential brain activation may be caused by differences in strategies...

  • when adults are presented with distractin spatial information, their spatial wm (working memory) gets impaired but not their verbal'. Also the other way around.
    • suggests a interplay betwen working memory and inhibition that is modality-specific
  • in children, however, if spatially distracting stimuli are presented, both verbal and spatial wm are impaired
    • functions and modalities seem to be less segregated in childhood