Week 3 Flashcards
3 timescales of brain plasticity
phylogenetic, developmental, ontogenetic (real time)
the earliest juggling was noted around _______ __
1994 BC
3 reasons for plasticity
changing demands through life, new skills/compensation for injury, changing environment
brain weight at birth
350 g
brain weight as adult
1300 g
are all neurons born by age 2?
no
neurons are added to the ____ and the _____ throughout life
olfactory, hippocampus
______ cells continue to develop throughout your lifetime
glial
brain volume changes from age 2 on are mainly due to _____ and _____ ______
myelination, dendritic branching
neurons extend axons to connect to other neurons via ______
synapses
axons must be _______ by glial cells
myelinated
time range for neural progenitor proliferation
4-12 weeks post conception
time range for neural migration
12 weeks to birth
time range for pruning/apoptosis
18 weeks post conception to childhood
time range for synaptotogenesis
18 weeks post conception to adolescence
time range for myelination
30 weeks post conception to adulthood
what is synaptogenesis
the formation of synapses
what is synapse rearrangment
the loss of some synapses and development of others , to refine synaptic connections
two kinds of regulation in brain development
intrinsic and extrinsic
intrinsic regulation
directed by genes, activity independent. Can only go wrong without oxygen, nutrition etc, or in presence of disruptors (hormones etc. )
extrinsic regulation
activity dependent - directed by neural activity, either generated spontaneously or driven by sensory input from the evironment
about _____ as many neurons are produced as found in adult brains
twice
% difference between human and chimp brain
1
is the entire cortex myelinated at the same time?
no, different portions are myelinated at different times
how many muscle fibers can be controlled by one neuron
many
how many neurons can control one muscle fiber?
one
in order to stay connected to another axon or a muscle fiber, a neuron requires ______ ______
trophic factors
Hebb’s rule
cells that fire together, wire together. Out of sync, lose your link!
when whiskers are removed from a rat, what happens to the ‘barrels’ of neurons in the cortex that they map to ?
the adjacent barrels expand
In Greenough’s study, what were the effects of “enrichment”
heavier cerebral cortex greater cortical cell bodies more dendritic spines more branching larger synaptic contacts 20% more synapses better learning better problem solving
in subordinate shrews, what was observed?
less branching, both apical and basal, less length in apical dendrites
the hippocampus has an annual turnover rate of ____
1.75%
adult neurogenesis is ______ in middle aged humans and mice
comparable
