Lectures 4 & 5 Flashcards
What are the two types of declarative memory?
Semantic and Episodic
Does the hippocampus receive and information directly from the outside world?
Nope, it all comes from the entorhinal cortex
Describe the pathway of the trisynaptic circuit
Entorhinal cortex to Dentate Gyrus Granule Cells via Perforant Path
Dentate Gyrus Granule Cells to CA3 Pyramidal Cells via Mossy fibers
CA3 pyramidal Cells to CA1 pyramidal cells via Schaffer Collaterals
Describe the set up for measuring LTP
Place a stimulating electrode on a pathway and a reading electrode on it’s end point in the extracellular space. Release a weak stim via theta bursts to get a baseline of reaction. Then release a STRONG stim via theta burst. Then test the same weak stim as you did during baseline to see the increase in synaptic activity
If the cell is achieving activation, what would we expect the extracellular charge to become?
Far less positive
What is the artifact caused by?
The sound of activation the machine
What is the fiber volley caused by?
Stimulation
The steeper the slope the ____ the cell activation
Greater
What is the extracellular matrix composed of?
Molecules synthesized and secreted by neurons and glial cells
What does the Post-Synaptic Density do?
Help bind the pre and post-synaptic neuron AND to position signaling molecules near glutamate receptors so that they can be activated and lead to long term change
What does the PSD contain?
Glutamate receptors, ion channels, signaling enzymes, and scaffolding proteins
What is an important scaffolding protein?
PSD-95
Besides PSD-95, what are some important proteins in the synapse?
- actin (provides scaffolding)
- functional proteins (enzymes that catalyze reactions and modify other proteins)
- endosomes (move receptors in and out of membrane)
- ribosomes (important for translating new protein)
- smooth ER (sequester and release calcium)
What kind of synapses are the main driver of LTP?
Excitatory synapses (glutamate receptors)
What does LTP represent?
An increase in synaptic strength (the amount of postsynaptic depolarization produced by the stimulus)
LTP is viewed as a Cellular Hallmark of ___ ____
Synaptic Plasticity
What does PSD-95 do?
Stabilize glutamate receptors to a region
Increases in PSD-95 could mean what?
More plasticity
What are the 4 stages of LTP?
Generation, stabilization, consolidation, maintenance
An increase in what can support LTP expression?
AMPA receptors
How would you test to see if NMDA is important to induction but not important for LTP?
Use an NMDA antagonist and see if induction and LTP occurs
What happens if you apply an NMDA antagonist right before stimulus?
No LTP AND no induction
What happens if you apply an NMDA antagonist after 30 minutes of a stimulus?
LTP still occurs
What must PHYSICALLY happen to the NMDA receptor to induce LTP?
The magnesium block must be removed
Expression of LTP involves an increase in AMPA receptors in the region of ____
PSD
How can you enhance the response of LTP using AMPA receptors? (Hint: 2 ways)
Make AMPA receptors stay open longer and increase the number of AMPA receptors in the dendritic spine
What are the two main processes the post-translational process mediated signaling cascades causes?
AMPA receptors are rapidly delivered to the PSD
Actin cytoskeleton is degraded temporarily so it can be rebuilt stronger and bigger
Does the traffic of AMPA receptors in and out of the spines happen at all times?
Yup
Where are AMPA receptors located?
Surface of dendritic spine and intracellular space of dendritic spine
How do AMPA receptors get recycled?
Proteins in the endocytotic zone perform Endocytosis and munch them inside the dendritic spine
What are the 3 steps of the constitutive process that deliver AMPA receptors to the membrane?
- intracellular vesicles w/ AMPA receptors (endosomes) are mobilized to deliver them in a region near the PSD
- the receptors diffuse into membrane to enter the PSD
- some receptors are trapped and others leave PSD to be recycled again
AMPA receptors contain THIS type of subunit under resting and basal conditions
GluA2 subunits
AMPA receptors contain THIS type of subunit under LTP
GluA1
What makes GluA1 special?
3 phosphorylation sites (Ser 818, Ser 831, Ser 845)