Wk2 Postnatal Brain Development Flashcards
when does neuronal production peak? what happens after that?
around 2 years of age
refinment or pruning
how do gray/white matter ratios change with age? what drives this effect?
gray to white matter ratios decrease, indicating more white matter than cell bodies as you reach adulthood.
prolific myelination drives the ratio, as gray matter cell densities actually increase with age (not decline)
what are transient events/neurons in development?
neural events that help with the wiring of the brain but will die before birth
5 main stages of neural circuit formation
- proliferation (production)
- migration and process formation
- initial synaptic contacts (can have transient targets/cells here )
- synaptogenesis & process elimination
- collateral elimination & synapse elimination
what does the presence of dendritic spines on a neurone reflect?
it is starting to form synapses and mature
if there is no activity happening when a neurone is forming a synapse, what two parts of it will disappear?
axonal boutons
dendritic spines
what determines the development of ocular dominance columns?
early visual/sensory experience
what are ocular dominance columns?
striped patterns on the visual cortex (4th layer) that recieve preferential input from either the left or right eye, in alternation
what was the effect on ocular dominance columns when a cat was deprived of vision in one eye? what does this show?
greater width of the columns from the eye that had input
the sensory information from vision determine the arrangement of columns in the cortex
in what way does the age at which a kitten stops receiving visual input in one eye affect ocular dominance column formation
what does this mean?
the earlier the eye was closed the greater the shift in columns?
very early sensory input is critical for long-term development
there is greater __ of intermingled sensory and motor neurons, with age. what does this suggest?
separation
neuronal projections are refined by experience
what process would allow a developing toddler to get better at motor movements?
refinement of axonal projections to specific muscle fibers and sensory cortices
strengthening or weakening of synapses is dependent on ___
recurrent timing of activity (action potentials)
hebb’s rule
‘neurons that fire together, wire together’
synaptic plasticity occurs ___ (when).
throughout life
what plastic changes are typical in sensory cortices over the lifespan?
rearrangement of topography maps (eg. if you learn the piano)
how does fMRI discriminate amateur and pro footballers? what does this show about experience?
when asked to move their foot in a circle pro footballers activated a smaller region of the motor cortex than amateurs
training and experience are able to refine the number of neurones needed to make specific movements
how does spontaneous eye activity determine the development of the thalamus? what is the effect of blocking activity in one eye?
the left and right monocular patterning at each side of the thalamus becomes more refined postnatally
the thalamus develops to have less segregation or specificity to the good eye
how does removing mouse whiskers 5 days after birth show that symmetry is important for sensory development? is it more important to have balance or symmetry of sensory input and what does this show?
removing only one side of whiskers prevents cross-hemispheric neuronal connections, but removing both sides results in normal development.
asymmetrical, balanced whisker plucking did not result in normal development, showing symmetrical activity is key to helping neurons find their targets
4 maternal factors that make up quality of care received by an infant?
nutrition
stress
sensitivity
deprivation
