Lecture 11 Flashcards
development of nervous system
neural plate- bunch of cells spread out from the back of the embryo, become nervous system, creates neural tube
the brain is a neural tube made by selective growth and folding
what happens if the tube fails to close
anencephaly- severe mostly fatal
spina bifida- not severe, human lives longer, spinal cord fails to develop
stages of neural development
neurogenesis migration differentiation synaptogenesis neural cell death synapse rearrangment
neurogenesis
start generating neurons
migration
migrate outward from division
ventricular zone is right next to tube and adjacent to NS
glial cells form connection with surface and ventricular zone
connection spreads out as nervous system grows like a rope
layer six forms first then layer 5 all the way to 2, layer 1 is just dendrites, axons, and synapses
differentiation
start to grow axons and dendrites that will characterize that kind of neuron
overproduction is followed by pruning
synaptogenesis
starts to grow synapses, creates pattern of connectivity
neuronal cell death
produces more neurons than it needs, then gets rid of them
growing side of growth cone is driven by
chemoattractants and chemorepellants
what happens if neurons don’t get neurotropic factors
neurons and individual synapses compete for neurotropic factors
if neuron doesn’t get neurotropic factor it is marked for death and removal
why cell death
neurons are overproduced, some play temporary role and then eliminated, some pared away based on improper migration
steps to apoptosis
high Ca2+ comes into cell and stimulates mitochondria, which releases diablo protein
diablo blocks inhibitors of cell death
releases capsules from inhibition, that break down cell
what prevents diablo release
Bcl-2 proteins
what leads to late appearance of some of the psychopathologies
late loss in prefrontal cortex leads to late appearance
Rosenzulvig environment experiments
social condition vs enriched condition
Greenough experiments
measure dendrites and synapses, enriched had more synapses per neuron, had greater volume (argued isolation paradigm)
does brain genome depend on instructions or environmental stimuli
brain genome does not need to have all the instructions correctly
it depends on environment, on sensory experience and on motor feedback check, to build networks for sensation and for movement
ex faith the wonder dog
sensitive period
period of time in which we are adding synapses and taking them away at the same time, moves into a phase where subtraction is bigger than addition
binocular deprivation
if it persists through the sensitive period, ex raised in darkness, can lead to blindness even though eyes and optic nerve are intact
monocular deprivation
causes profound abnormalities in the wiring of the visual system, can lead to blindness in one eye
one eye deviated
if one eye is deviated, each cortical cell will listen to one eye or the other resulting in poor depth perception
amblyopia
visual input for one eye not competing for cortical influence properly
misalignment of one eye, lazy eye
can be modified by blocking input from “good eye”
this allows both eyes to function, but binocular depth perception is impaired
how can epigenetic affect physiology and behavior across generations
chemically attaching a methyl group to a patch of DNA inhibits its expression
this can occur in small regions of the brain in response to stimulation
the methylination can be copied with the DNA, so the change in function can pass from one generation to the next
