Lecture 6 Flashcards
changes in synaptic transmissionn is known as
synaptic plasticity
what is synaptic plasticity
changes in synaptic transmission
synaptic plasticity is a change in how well a ______ cell can fire
pre synaptic cell
synaptic plasticity is the basis for ____ and _____
learning and memory
synaptic plasticity can result from changes in
- the amount of neurotransmitter released
- the amount of receptor present
- gene expression that affect these mechanisms
- gene expression that affect the growth of new synapses
t/f plastic changes only occur for a few seconds
false, plastic changes can be over in miliseconds or over a lifetime
when measuring setup for measuring plasticity does the stimulating electrode go into the presynaptic or post synaptic neuron
presynaptic
when measuring plasticity does the recording electrode go into the pre or post synaptic electrode
post synaptic
if a presynaptic neuron is stimulated what will occur
if a presynaptic neuron is stimulated it will cause a psp in the post synaptic cell
what does the amplitude of psp tell you
it tells you how good the presynaptic neuron is at making the post synaptic neuron fire
what are the 3 steps to measuring synaptic plasticity
- measure the psp at baseline
- induce plasticity by giving a high frequency stimulus (tentanus)
- go back to baseline
what is tentanus
the delivery of a brief high frequency stimulus
an incident of high frequency can change the _____of a cell
plasticity
usually the magnitue of a psp is plotted relative to what
the baseline
when recording plasticity what are we measuring
we are measuring the synapse
the day your child was born or ptsd is an example of
high frequency stimulation
t/f high frequency is usually tied to negative events
false it can occur from negative or positive events
define short term plasticity
occur and maintains itself for at most a few minutes
how does short term plasticity occur
it results from repeated stiumulation of the same synapse
t/f long term synaptic plasticity can last for a few years
true
t/f all plasticity begins with immediate short term change
true
what are the 2 types of long term synaptic plasticity
2 : long term potentiation and long term depression
what does LTP mean
long term potentiation
what does LTD mean
long term depression
define LTP
an increase in the size of the EPSP that is sustained for at least several minutes . it strengthens the synapse since it makes the presynaptic more likely to fire
does LTP make a pre synaptic cell more or less likely to fire
more likely
how long does LTP last
for months or years
define LTD
a decrease in the size of the EPSP that is sustained for at least several minutes
does LTP or LTD weaken the synapse
LTD
During LTD is a cell more or less likely to fire
less
how long can LTD last
for months to years
what determines if you will have LTD or LTP
The pattern of presynaptic stimulation determines whether there will be long term plasticity and of what type
if there is a slow pattern of presynaptic stimulation (1 hz) will you have LTP or LTD
LTD
If there is a fast pattern of presynaptic stimulation (100 hz ) will you have LTD or LTP
LTP
T/F All neurons have the same ability to show LTP or LTD
False, different types of neurons differ in their ability to show LTP or LTD
t/f if you want study LTP and LTD you must choose the right area of the brain
true
name one site of LTP and LTD
The hippocampus
name the area of the brain that is involved in the formation and retrieval of episodic memory
hippocampus
what is episodic memory
memory of autobiographical events
what is the name of the main input site in the hippocampal circuit
perforant path
if there is damage to the hippocampus what will likely occur
what you already will not be affected, but you will not be able to make new memories
describe the 1st synapse in the hippocampal circuit (trisynaptic circuit)
synapse with the granule cells of the dentate gyrus
what is the name of the axons on granule cells
mossy fibers
what kind of cells are located in the ca3 region
pyramidal cells
where do mossy fibers extend to
the ca3 region
pyramidal cells in the ca3 regionn send axons to what region
ca1 region aka schaffer collaterals
schaffer collateral links what 2 regions
ca3 - ca1
if you wanted to investigate LTP what would you stimulate
shaffer collaterals in 2 places to have both a test and a control pathway
if you delivered a High frequency stimulation to pathway 1 and not to pathway 2 what would you observe
in pathway 1 the frequency would remain higher after the stimulation . in pathway 2 there would be no change in the synapse
what does HFS induce
LTP
high frequency stimulation induces a long lasting increase in what
synaptic transmission
define specificity
when something is synapse specific
the hippocampus is what we call the _______ circuit
trisynaptic
what kind of cells are in the ca3 region
glutamatergic excitatory pyramidal cells
what kind of cells are in the ca1 region
glutamatergic excitatory pyramidal cells
information is sent out of the hippocampus via what
the sabicculum
when a recording is done in vivo what does that mean
on a live animal
t/f hippocampal LTP can only last for a few months
false , it can last for years
HFS simulates the ______ cell firing at a high rate
presynaptic cell
why does HFS cause LTP
more neurotransmitters are released so receptors have to respond so the cells knows that it is important so they will strenghthen the synapse
what is hebbs law
neurons that fire together , wire together
this is an example of what law? when an axon of cell A is near enough to cell B and repeatedly or persistently takes part in firing it , some growth process or metabolic change takes place in one or both cells such that A’s efficiency as one of the cells firing B is increased
hebbs law
a strong stimulation at one synapse strengthens transmission at a weak synapse , this is an example of what
associative concept
if there is a high frequency stimulation at pathway 1 and inactivity at pathway 2 what will occur
synapse 2 will never strengthen
if there is strong stimulation at pathway 1 and weak stimulation at pathway 2 what will occur
because both are occuring at the same time , it will strengthen
high frequency stimulation induces what where
hfs induces ltp at the hippocampal schaffer collateral ca1 synapse
t/f LTP is not hebbian in nature
false
t/f weak synapses coincident with strong synapses will not demonstrate LTP
false
what is released at the presynaptic terminal
glutamate
what are the 2 kinds of receptors at the post synaptic terminal
AMPA and NMDA receptors
when the pre synaptic cell releases glutamate is it depolarized or hyperpolarized
depolarized
what are spines
excitatory synapses that are small protrusions
where are spines found
they are excitatory synapses on hippocampal and cortical dendrites are often on small protrusions called spines
if someone has fewer spines what can occur
mental retardation
are AMPAR and NMDAR’s found on the pre or post synaptic cell
post synaptic
if transmission rates are low and the post synaptic membrane is at rest what kind of receptors are open
AMPAR
T/F at low transmission rates only NMDAR are open
false , only AMPAR are open
if transmission rates are high which receptors are open
AMPAR and NMDAR
when transmission rates are high is the post synaptic membrane hyperpolarized or depolarized
depolarized
when NMDAR open a series of events occur which ultimately ends with ..
the insertion of more AMPAR into the membrane
what physically strengthens a synapse
the insertion of new AMPAR
what is the role of the NMDAR
without it more ampa receptors can not be inserted , essentially you can not learn
t/f without NMDAR you can not have LTP
true
what 2 things have to open in order for NMDAR’s to open
post synaptic depolarization and glutamate
t/f AMPAR’s are known as coincidence detectors
false , NMDARs are
what kind of receptor is known as a coincidence detector ?
NMDARs
what ion calcium comes in when NMDAR’s open ?
calcium comes into the terminal
what ion is crucial for LTP
calcium
what is the role of calcium chlelators
they block LTP
What does the injection of calcium do to a cell
it potentiates transmission
influx of calcium activates what 2 things
activation of 2 kinases : alpha camkinase and protein kinase
what is the name of the most abundant postsynaptic protein at the schaffer collateral synapse
CAmkii
where are the only 2 places that camKii is released
the cortex and hippocampus
if there is no caMkII is LTP possible
no
camKii are able to stimulate their own activity via
autophosphorlation
persistence of CamKII activity is due to what
autophosphorlationn
what allows for the insertion of more AMPARs
alpha cam kinase and protein kinase
during hippocampal LTP what receptors open first
NMDAR’s open first
what ion rushes in after NMDARs open during hippocampal LTP
calcium
More AMPARs = more ____
potentiation
the increase of LTP is more synaptic strength or less synaptic strength?
more synaptic strength
does schaffer collateral have a pre or post synaptic locus of plasticity
postsynaptic
when there is ampar insertion does this result in an increase in LTP or LTD
LTP
When LTP increases , this results in an increase in amplitude of _______
EPSP
what is L-LTP
Late LTP
If you apply protein synthesis blockers what occurs to to LTP.
you get LTP but it decays after several hours
L-LTP depends on what 2 things
gene transcription and protein synthesis
L-LTP leads to the growth of new ____
spines
t/f cells can potentiate all the time
false
the flip side of long term potentiation is known at
LTD
You get LTD at the schaffer collateral synapse by using what ?
prolonged low frequency stimulation - 1 hz
is LTD associated with the gain or loss of AMPARs
loss
instead of kinases , LTD relies on what
calcium dependent phosphatases
are phosphotase inhibitors affected by LTP
No, only LTD
whether you get LTP or LTD depends on what
the amount of calcium influx
if there is a large and fast influx of calcium will LTP OR LTD RESULT?
LTP
If there is a small and slow influx of calcium will LTD or LTP occur
LTD
During LTD are AMPARs created or taken away
they are taken away
name a site of LTD
cerebellum
this part of the brain is involved in motor control and responsible for several types of motor learning
cerebellum
where does LTD occur in cerebellum
at the parallel fiber purkinje cell synapse
LTD at the cerebellar LTD only occurs when what 2 fibers are activated at the same time
climbing fibers and parallel fibers
during LTD what happens at the climbing fiber synapse
climbing fiber input depolarizes the dendritic membrane.
