22 Questions
What is the role of Ca2+-calmodulin in CaMKII?
Disinhibits kinase activity
Phosphorylated CaMKII is constitutively active until dephosphorylated by a phosphatase.
True
What is the mechanism of storing memory in CaMKII molecules?
The memory is stored in the number of CaMKII molecules within a ring that are phosphorylated.
Back propagating dendritic APs can open _____________ channels in dendritic spines.
voltage-dependent Ca2+
What is required for long-term memory formation?
Protein synthesis
NMDA receptors are the only source of Ca2+ for plasticity.
False
Match the following molecules with their functions:
CaMKII = Involved in memory formation CREB = Regulates gene expression Phosphatase = Dephosphorylates CaMKII
Ca2+ entry via NMDA plus voltage-dependent channels is greater than the sum of separate routes of entry by ____________.
themselves
What is the criterion for Long Term Potentiation (LTP) to occur?
When pre- and post-synaptic neurons are active at the same time
Long Term Depression (LTD) results in a larger response in neurons.
False
What is the name of the bacteria that is associated with the term 'tetanus' in the context of neural stimulation?
Clostridium tetanus
The effect of LTP lasts for more than ______________________ month.
1
Match the types of neural stimulation with their effects on neuron response:
Tetanic stimulation = Larger response Low frequency stimulation = Smaller response
What would happen to memories if LTP and LTD were the only mechanisms operating in the brain?
Associations would always drive memories towards a single memory
What is the effect of the timing of the back-propagating AP and the EPSP on LTP/LTD?
If AP precedes EPSP, it leads to LTD
NMDA-receptor mediated EPSP occurs before post-synaptic AP, leading to a small increase in intracellular Ca2+.
False
What is the role of CaMKII in memory formation?
activates protein synthesis
The calcium-dependent phosphatase activated during LTD is ______________________.
Ca2+-dependent phosphatase
What is the function of mGluR1 in Ca2+ entry?
causes Ca2+ release from endoplasmic reticulum
Hermann Ebbinghaus was a neuroscientist who studied the mechanisms of LTP.
False
Match the following receptors with their functions:
mGluR1 = Opens voltage-dependent Ca2+ channels NMDA = Causes Ca2+ release from endoplasmic reticulum
What is the significance of the timing of Ca2+ entry in determining LTP/LTD?
The timing of Ca2+ entry determines whether LTP or LTD occurs.
Study Notes
Calcium-Calmodulin Dependent Protein Kinase II (CaMKII)
- Associated with postsynaptic density in spine cytoplasm
- Consists of 10 subunits/enzymes, each activated by calcium-calmodulin
- Ca2+-calmodulin disinhibits kinase activity, leading to autophosphorylation
- Phosphorylated CaMKII is constitutively active until dephosphorylated by a phosphatase
- Memory is stored in the number of phosphorylated CaMKII molecules within the ring
Regulation of Protein Synthesis
- Phosphorylation, receptor sensitization, and increased receptor number are time-limited
- Long-term memory requires protein synthesis
- Phosphorylation of CREB (cyclic AMP Response Element Binding protein) regulates gene expression in invertebrates
NMDA Receptors and Calcium Entry
- NMDA receptors are not the only source of Ca2+ for plasticity
- Back-propagating dendritic action potentials can open voltage-dependent Ca2+ channels in dendritic spines
- Ca2+ entry via NMDA receptors and voltage-dependent channels is greater than the sum of separate routes
- Ca2+ can also be released from intracellular stores via metabotropic glutamate receptors (mGluR1)
Back Propagation of Action Potentials and LTP/LTD
- Back-propagating action potentials activate voltage-dependent Ca2+ channels
- Timing of Ca2+ entry is critical for LTP/LTD
- If the action potential precedes the EPSP, LTD occurs
- If the EPSP precedes the action potential, LTP occurs
Spike Timing Plasticity
- When an action potential occurs before an EPSP, a small increase in intracellular Ca2+ leads to LTD
- When an EPSP occurs before an action potential, a large increase in intracellular Ca2+ leads to LTP
- The timing of the back-propagating action potential and EPSP determines LTP/LTD
Hebbian Modification and LTP/LTD
- Hebbian modification includes LTP (long-term potentiation) and LTD (long-term depression)
- LTP: synapses strengthen when pre- and post-synaptic neurons are active at the same time
- LTD: synapses weaken when pre- and post-synaptic activity is not simultaneous
- LTP and LTD are a result of Hebbian modification in hippocampal neurons
This quiz explores the role of Calcium-calmodulin dependent protein kinase II (CaMKII) in memory formation, including its structure, activation, and phosphorylation mechanisms.
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