Lec 16 Flashcards
short term plasticity of different kinds may be caused by ..
repetitive stimulation of a synapse
While studying NMJs, how could you enhance a motor endplate to undergo depression?
treat the endplate with curare and place it in high Ca2+ solution
short-term presynaptic plasticity usually reflects changes that occur where?
presynpatic changes
What type of long term plasticity takes place when phosphorylation of the AMPA receptors occurs?
LTP
Which type of short term plasticity causes an increase in synaptic strength that outlasts the period of high-frequency stimulation?
Potentiation
repetitive electrical stimulation of the sensory neuron that leads to progressive decrease in the size of the postsynaptic response is known as…
habituation
repetitive stimulation of a neuronal synapse that yields an increase in strength which lasts ten to hundreds of milliseconds is known as…
facilitation
Quantal release (during LTP) changes how?
quantal release doesn’t change, more NT (glutamate) is recepted our bound to receptors in the postsynaptic membrane by the addition of receptors during the onset of LTP.
During LTP is single quantal current changed?
No
Does LTP change the size of the response to a single quanta released from a presynaptic terminal in the brain?
No, but it does change the number of quanta detected
low concentrations of Ca2+ inside the postsynaptic terminal of the hippocampus during low frequency presynaptic activation, will lead to what type of response in the postsynaptic membrane?
it leads to activation of protein phosphatases, which dephosphorylate the AMPA receptors and deactivating them and removing them from the postsynaptic membrane. The result is LTD
what protein kinase (in LTP) activates AMPA receptors by phosphorylating them and/or inserting them into the postsynaptic membrane?
Ca-calmodulin-dependent protein kinase
Both LTP and LDP are dependent on …
postsynaptic Ca2+ levels. HIGH levels (LTP) LOW levels (LDP)
repetitive stimulation of a neuronal synapse that yields an increase in strength which lasts tens of seconds to several minutes and outlasting the period of high-frequency stimulation is known as…
potentiation
repetitive stimulation of a neuronal synapse that yields an decrease in strength which occurs over a high frequency of activation is known as…
Depression
Potentiation is a form of short term plasticity that causes what kind of change in synaptic activity?
increases in synaptic strength which lasts several seconds to serveral minutes and outlasts the period of high-frequency stimulation.
If 5 quantum are released and reach the 5 postsynaptic spines that contain NMDA receptors. Of the 5 spines, 3 contain AMPA receptors as well. What is the quantum response with no postsynaptic depolarization?
3 –> quantum responses can only be registered with AMPA receptors without postsynaptic depolarization.
repetitive stimulation of a neuronal synapse that yields an decrease in strength which occurs over a low frequency of activation is known as…
Habituation
What marine mollusc is used to study synaptic plasticity, learning, and behaviour?
Aplysia Californica
Hippocampal neurons can undergo a long term increase in efficacy known as:
LTP
which postsynaptic receptor in brain is responsible for postsynaptic Ca levels?
NMDA
Facilitation is a form of short term plasticity that causes what kind of change in synaptic activity?
increases synaptic strength (ave. amplitude) which lasts tens to hundreds of milliseconds.
What type of long term plasticity takes place when dephosphorylation of the AMPA receptors occurs?
LTD
AMPA receptors on the postsynaptic membrane are inactivated and removed from the postsynaptic membrane when under the effects of what type of long term plasticity?
LDP
LTP has been heavily studied in what part of the mammalian brain?
hippocampus
What type of synaptic plasticity causes a decrease in stimulus strength over a low frequency of activation?
Habituation
In the Aplysia Californica, habituation effects can last a long period of time … around 50% at ____ weeks.
three weeks @ 50% duration of withdrawel
LTP only occurs upon activation of what postsynaptic receptors in the brain?
AMPA and NMDA
In the Aplysia Californica, sensitivity decreases stimulation, however it returns after what amount of time?
around 1 day.
Augmentation is a form of short term plasticity that causes what kind of change in synaptic activity?
increases in synaptic strength which lasts several seconds
cooperativity requires what kind of activation of LTP?
2 or more coincident activations that cause presynaptic activation and postsynaptic depolarization.
What are the key advantages of studying memory with a Aplysia Californica?
- very simple nervous system 2. simple behavioural repertoire
While studying NMJs, How could you enhance a motor endplate to undergo facilitation?
bathe the endplate in a low Ca2+ solution
What happens in the presynaptic terminal at a NMJ that may cause Facilitation to take place?
Accumulation of Ca2+ in the presynaptic membrane following each Action potential which consequentially increases the probability of more neurotransmitters being released from vesicles.
In a presynaptic terminal within the brain, which type of NT vessel is located near the calcium channels?
secretory vesicles that contain the NT glutamate (in the brain)
In the Aplysia Californica, tactile stimulation of the gill and siphon reflex undergoes what type of short term synaptic plasticity?
habituation - the current response decreases with each stimulus .
The type of release that occurs at the presynaptic terminal can be influenced by…?
the rate and pattern of action potential firing
What does synaptic plasticity mean?
the term for activity-dependent changes in the effectiveness of synapses.
Hippocampal neurons can undergo long term decrease in synaptic efficacy (strength) by doing what?
providing a low frequency presynaptic activation (1Hz) until the postsynaptic cell is depolarized.
In the Aplysia Californica, tactile stimulation of the gill and siphon reflex undergoes habitation. How would you dehabituate ?
a single large shock stimulus rehabituates and removes the effects of habituation.
What is defined as the pairing, association, or cooperation of enough presynaptic stimulus in order to strongly activate the post synaptic cell?
classical conditioning
In plasticity, longer lasting stimuli require what kind of conditioning?
longer condition.
During LTP, how does the postsynaptic terminal provide regulation for the presynaptic cell?
In LTP, the postsynaptic cell will somehow signal the presynaptic cell and cause enhanced Neurotransmitter release.
What can occur at “many excitatory synapses in the brain” ?
LTP
What type of long term plasticity takes place when protein phosphatases are activated?
LTD
Habituation is a form of short term plasticity that causes what kind of change in synaptic activity?
a decrease in synaptic strength which is slowly progressing decrease that occurs during relatively low frequency activation.
What are 2 mechanisms used to cause a synapse in the brain to undergo LTP?
- rapid repetitive stimulation of one input or 2. Associative ATP or cooperativity –> presynaptic stimulation as well as postsynaptic depolarization by another input.
which postsynaptic receptor in the brain is both voltage and ligand gated?
NMDA
Is LTP most likely a presynaptic or postsynaptic effect?
most likely a postsynaptic effect due to AMPA and NMDA receptors , but it is speculated that it could be due to an increase in release of quanta in the presynaptic terminal.
What happens in the presynaptic terminal at a NMJ that may cause Depression to take place?
may be caused by the depletion of vesicles from the terminal.
Why do synaptic spines only containing NMDA receive no quantal response?
NMDA undergoes a silent synapse when the post synaptic membrane potential isn’t positive enough. No signal is transmitted.
What type of long term plasticity takes place when protein kinases are activated?
LTP
repetitive stimulation of a neuronal synapse that yields an increase in strength which lasts several seconds is known as…
augmentation
While studying LTP in a rat hippocampus, you discover that stimulus 1 is very weak and by repeating the stimulus you are unable to induce LTP. What can you do in order to induce LTP?
Create a 2nd stimulus that is Strong enough to compensate for the weak stimulus and depolarize the postsynaptic cell.
What type of long term plasticity uses Ca-Calmodulin kinase and Protein kinase C?
LTP
High concentrations of Ca2+ inside the postsynaptic terminal of the hippocampus during high frequency presynaptic activation, will lead to what type of response in the postsynaptic membrane?
leads to activation of Ca2+/calmodulin kinase and protein kinase C will phosphorylate synaptic proteins (AMPA) and promote their activation/entrance into the postsynaptic membrane. The result is LTP
What are the two types of protein kinases activated in LTP?
Ca-Calmodulin kinase and Protein kinase C
AMPA receptors on the postsynaptic membrane are activated and placed in the postsynaptic membrane when under the effects of what type of long term plasticity?
LTP
What must happen to a pre and postsynaptic neuron in order for LTP to take place?
Presynaptic terminals must be activated at the same time as Postsynaptic depolarization
Trains of high-frequency stimulation of a specific synapse can lead to long lasting increase in synaptic strength this is known as:
LTP long term potentiation
What type of synaptic plasticity causes a decrease in stimulus strength over a high frequency of activation?
Depression
In the Aplysia Californica, the classical conditioning of of both the gill and tail stimulus caused what type of results?
an increased duration of siphon withdrawal. (greater than either of them stimulated alone)
Hippocampal neurons can undergo long term decrease in synaptic efficacy (strength) called:
long term depression LTD
LTP is induced by the introduction of what type of receptors into the postsynaptic spine?
AMPA
What type of synaptic plasticity is synapse specific and studied in the CA1?
LTP (possibly LDP)
What is the name of the accumulation of Ca2+ in the presynpatic membrane following a train of high frequency AP that increase in strength with each fire?
Facilitation
Depression is a form of short term plasticity that causes what kind of change in synaptic activity?
a decrease in synaptic strength, and can occur during high-frequency stimulation
Can depression occur during high-frequency stimulation?
Yes, it is short term plasticity (its a decrease in str.)
expression of LTP in the Ca1 region of the hippocampus depends on what?
activation of Ca2+ dependent kinases (Ca-calmodulin-dependent protein kinase)
