w5 VSE changes in vision from birth Flashcards
(17 cards)
how does vision change overtime??
acuity
spatial and temporal contrast sensitivity functions
colour vision (colour perception; colour naming)
why does vision change so rapidly after birth??
size, shape and density of cones
development of lateral inhibition at abt 2 months of age
post retinal factors like: at birth myelination of nerve fibres is incomplete - particularly in the higher visual pathways, post-natal increase in cell size, post-natal changes in synaptic density, changes may continue up to 9-12 years of age
post retinal factors
at birth, myelination of nerve fibres is incomplete - particularly in the
higher visual pathways
– post-natal increase in cell size
– post-natal changes in synaptic density
* changes may continue up to 9-12 years of age (or even later).
how does vision change after birth?
it improves rapidly due to optical, retinal and neural development
is colour vision present at birth?
weakly, cones are immature; colour discrimination develops over the first few months
when does an infants trichromatic colour vision become more adult like??
by around 3-5 months of age
what is forced-choice preferential looking??
a behavioural method using infant’s gaze preference to measure VA
what is visually evokes potesntial VEP??
an objective method measuring brain activity in response to visual stimuli
why is VEP acuity higher than PL acuity??
because VEP bypasses behavioural limitations and directly measures neural responses
what is synaptogenesis??
formation of synaptic connections bet neurons essential for visual processing.
what is myelination and how does it affect vision??
it is insulation of nerve fibres to speed up signals; improves visual processing speed and acuiity
how do post-retinal factors impact visual development??
they enhance processing and integration of visual information in the brain
how do the eye’s optical properties change after birth??
corneal curvatures flattens, axial length increases, and the lens changes shape for clearer focus
what is meant by the “waveguide property” of photoreceptors??
it describes how mature cone photoreceptors direct light efficiently for better image resolution
(from inner segment out segemnt of cone to funneling property of cone where light can be guided into teh interior space of the receptor)
Why is early visual experience crucial?
It shapes neural development during critical periods, influencing lifelong visual ability.
What 3 main systems undergo post-natal development to improve vision?
1) Optical components (cornea, lens, eye size)
2) Retinal maturity (cone development)
3) Post-retinal/neural pathways (synaptogenesis, myelination)
key difference in 6month infant Vs adult (spatial contrast sensitivity function)
x axis: spatial freq cycles per degree cpd
y axis contrast sensitivity (1/ contrast threshold)
peak sensitivity: adult: ~3-5cpd 6m: ~1-2cpd
max contrast sensitivity: a: ~100-150 6m: ~10-20
overall shape: a: band pass 6m: flatter band pass
high freq cut-off: a: up to ~30-40cpd 6m: ~4-6cpd
reason of diff: a:fully developed retina, optics& cortical processing 6m: Still developing retina(esp fovea), optics& visual cortex
Feature | Adult | 6-month Infant |
