the developing brain Flashcards
history: middle ground perspective
interaction between environment and genetic factors
eg. Piaget/neuroconstructivism
what are the different theories within the nature/nurture debate?
blueprint analogy
predetermined development
probabilistic development
describe Gottlieb’s different views of development
Predetermined development
Probabilistic development
what is Predetermined development?
genes–> brain structure–>brain function–>experience
what is Probabilistic development?
genes<–>brain structure<–>brain function<–>experience
effects of genes on brain structure themselves are probabilistic: specify approx. how and where neurons develop
variation, not copy = MZ twins
what are the steps within prenatal brain development?
cell division
cell specialisation
neural tube formation
neural tube differentiation
neural tube formation
proliferative zones: neurons and glial cells produced
250,000 neurons produced/min
neurons migrate to final location
what occurs during neural tube formation?
develops into spinal cord and brain
what structural features emerge from constraints?
- folded cortex emerges from having lots of neurons
- pattern of gyri/sulci pulled into shape by tension of axon bundles
- Hebbian learning: Spontaneous electrical activity enables networks to form eg. retina
what causes the postnatal increase in brain size?
synaptogenesis
myelination
glial cell proliferation
what is plasticity?
experience
dependent change in neural
functioning
can lead to small but observable structural changes
how is plasticity evident in the brain?
increased grey matter: new synapses, dendrites, axon collaterals, glia cells
what is functional brain development?
prenatal brain
damage can lead to major reorganisation of
tracts
eg. AH with no right hemisphere
how is functional brain plasticity limited?
Spontaneous electrical activity enables networks to form
intrauterine – connections not fully lost
Opportunities for major reorganisation are time-limited =critical or sensitive periods
what is filial imprinting?
the process
by which young animals learn
to recognise the parent
- 15hrs-3 days
- movement is crucial
what are the 2 main features of critical and sensitive periods?
- Learning takes place within a limited window
o But opportunity can be extended in lack of experience - This learning is hard to reverse by later experiences (but can generalise to similar objects) (preference can be changed after)
phenomic discrimination between ‘r’ and ‘l’ is an example of…
critical and sensitive periods
what are the explanations of c+s periods?
genetically programmes synaptogenesis followed by reduced plasticity
closure of window initiated by learning
what is the empiricist view on innate knowledge?
newborn mind is a blank state
what is the nativist view on innate knowledge?
we are born with some knowledge
what is the more modern view on innate knowledge?
Innate = readiness to learn
Knowledge or behaviour that arises in the absence of appropriate
experience
eg. cat visual cortex
eg. preferences
prenatal ultrasound shows:
structure: different types of tissue have different physical properties
creates STATIC maps
How can we
investigate
brain
development?
prenatal ultrasound
prenatal MRI
behavioural methods
from behaviour, we can infer:
brain development
eg. Preferential looking paradigm
what is meant by ‘functional’ in neuroscience methods?
temporary changes in brain physiology associated with
cognitive processing (e.g. fMRI)
what is the problem of functional neuroscience methods?
Usually, we ask participants to perform some kind of task or to sit/lay still and look at images
Infants won’t perform tasks and they won’t even stay still
what are functional neuroscience methods that can be used with infants and young children?
Electrophysiological response (electromagnetic fields in brain) eg. EEG/ERPS
Haemodynamic response (brain blood supply)
eg. fMRI, fNIRS
infant EEG
Infant friendly EEG
systems/solutions that allow
quick installation
Infant friendly stimuli
More breaks during the study
infant vs adult ERPs
Some adult ERP peaks
are present in infants,
but delayed: e.g. visual
ERPs
eg. N1/N290: Perceptual
and/or face specific
component
some ERP components only present in infants and toddlers:
Negative Central peak
Typically peaks between 300-
700 ms after stimulus onset
Reflect attention
Larger peak reflect higher
attention
why is fMRI not ideal for infants?
Highly sensitive to
motion artifacts
Loud, restrictive
environment
but some recent attempts
eg. face specific
activity in the brain
fNIRS
measures BOLD signal
(blood oxygen-leveldependent contrast) using near infrared spectrum
Skin, tissue, and bone are mostly
transparent to NIR light
Measures the concentration changes of oxyHb and deoxyHb focally, related to
brain activity
how to compute BOLD response?
from the difference between emitted and
detected NIR
Hb and deoxyHB absorb of NIR
NIRS vs fMRI
NIRS can be an appropriate substitute
NIRS cons
fNIRS has lower spatial resolution
Only the surface of the cortex can be imaged
Often only a few sensors are used above a
certain brain area
NIRS pros
Portable
More tolerant of movement
