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17 Cards in this Set
- Front
- Back
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What is Synaptic Plasticity?
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Changes in brain synapse efficiency
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What are 2 ways by which synaptic plasticity can be changed?
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-Alterations in Presynaptic neurons
-Alterations in Postsynaptic neurons |
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What are 2 forms of synaptic plasticity seen in presynaptic neurons?
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-NT synthesis changes
-Axoaxonic modulation |
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What are 3 ways that NT synthesis can be modified to accomplish synaptic plasticity?
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-Regulation of the RLS
-Substrate availability -Enzyme induction |
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What is an example of an enzyme that regulates the RLS of NT synthesis and can be changed to alter the presynaptic neuron release of NT?
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Tyrosine hydroxylase
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What does TH require to be active?
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Pteridine
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What does an AP do to TH?
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Changes it from a low affinity state (high Km for pteridine binding) to a high affinity state (low Km for pteridine)
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What are 2 ways to prevent AP's from lowering the Km of TH for pteridine?
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-Increased Dopamine in the cytosol (regulatory pool)
-Autoreceptor binding of DA |
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What is the result of a higher Km for pteridine in tyrosine hydroxylase?
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Less Dopamine synthesis
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How is enzyme induction accomplished?
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By the expression of GENES - regulation of TH thru changes in affinity are NOT an example of induction.
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How do axo-axonic synapses accomplish synaptic plasticity?
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By regulating the release of NT's from axons
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What are 2 general forms of axoaxonic synapse regulation of plasticity?
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-Presynaptic inhibition
-Presynaptic facilitation |
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How does Presynaptic inhibition work?
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The modulatory neuron decreases the amount of Ca influx into the presynaptic neuron upon AP stimulation, so that less NT is released, for a lower EPSP.
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What is the mechanism by which the NT released from the regulatory neuron causes reduced calcium influx into neuron A?
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Activation of the B-y subunit of a GPCR inhibits the Ca channel
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How does Presynaptic FACILITATION work?
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NT binds to a presynaptic terminal and inhibits K channels to suppress potassium-mediated hyperpolarization, prolong the AP, Ca influx, and EPSP.
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and how exactly does the increased and longer Ca influx raise the EPSP?
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By increasing NT release
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What are 3 ways to alter postsynaptic sensitivity to achieve synaptic plasticity?
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-Summation
-Changes in receptor number -Changes in efficiency of coupling receptors/transducers |
