Lecture 4 Q &A Flashcards
What does short term habituation do?
changes the synapse
What does long term habituation do?
changes the number of synapses
What does habituation do in the brain?
Habituation decreases the number of synapses
What does sensitization do in the brain?
Sensitization increases the number of synapses.
Describe sensitization?
Kinase pka is activated and lots of it in long term training goes to the genome.
What does Creb 1 do?
“Good Creb” it activates memory and turns on genome leading to growth or sensitization (long term memory).
What does Creb 2 do?
“Bad Creb” Inhibits long term memory
Describe the Hebb synapse/ Hebb’s Law?
When an axon of a cell A is near enough to excite 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.
“Neurons that fire together, wire together”.
Where are pyramidal cells located?
CA1 and CA3
Where are granule cells located?
DG
How has the synaptic strength changed as a result of the titanic synapse?
The EPSP is very high and continues to stay this way for a long period of time. This is the “zap”.
What is the inhibitory neurotransmitter?
GABA
What is the excitatory transmitter?
Glutamate
Describe the experiment with the electrode and rat hippocampus
Drop electrode to record electrical results from dentate region. You stimulate and record this region to see how big it is
Describe the LTP experiment
1) Establish size of LTP
2) High frequency stimulation (tetanus or zap)
3) Redo #1
LTP is a large sustained (hours long, even days) increase in the size of the EPSP after the zap stimulation.
Describe Phase 1 of LTP experiment
Block half NMDA = no effect
AMAP receptors are enough to give normal EPSP
Why we care about LTP in relation to memory.
1) prominent in hippocampus in vivo
2) develops rapidly
3) lasts a long time
4) shows synaptic specificity
5) shows associativity
6) optimal at theta rhythm
7) drugs that enhance memory generally enhance LTP, drugs that pair memory generally impart LTP
8) It consolidates
9) Burst firing in hippocapual pyramidal cells.
What enhances vs inhibits LTP?
Enhances LTP: Acetaminophen
Inhibits LTP: Benzadiazopenes
What is LTP associativity?
If 2 inputs are stimulated sub threshold they can combine to form LTP
What did Eric Harris focus on?
AP 5 or APV NMDA antagonist
Glutamate only activates __ receptors to for ___
AMPA and EPSP
Describe the Morris Water maze.
Rat was placed in a water bath that is shrouded and covered in powdered milk. The rat is tasked with finding the platform. It was found that over multiple trials the rat began to quickly be able to find the platform which helped suggest evidence that it had indeed created a cognitive map in its head to do so.
What did Morris and Lynch do?
They localized AP5 injections to inactivate LTP int he hippocampus to see if it would prevent learning. They also used a guide cannula to do so.
“The door to meaning is behavior”.
Explain the paw reaching task
Localized LTP tissue and control LTP tissue similar to it was present in the experiment. The rat’s time it took to get food by reaching out its paw was measured. This was the “ultimate experiment” for reacting LTP to memory.
Why were males prominently studied rather than women In the past?
This is because it was believed that LTP mechanisms in the genome was the same for both males and females. When that is in fact not the case.
What did Chris Gall and Gary Lynch do?
Examined mechanisms of LTP in Schaffer Collaterals axons of CA3 cells projecting to dendrites of the CA1 cells in female and male rats and how this relates to learning.
What was key finding 1 of the Gall and Lynch study?
Local estrogen (in neurons)
Blockade of ER alpha not ER beta receptors blocks LTP formation in females. So estrogen in cells acts via ER alpha to form LTP but only on females.
2) Found that ER alpha receptor activation in turn activated NDMA enzymes that are critical to making LTP but only in females.
3) Much lower levels of ER alpha receptors in males than in females which explains why males do not use this mechanism.
What was key finding 2 of the Gall and Lynch study?
Infused or added estrogen (mimicking hormonal estrogen)
4) Infused estrogen acting through both ER alpha and ER beta receptors activates the same NMDA enzymes needed for LTP.
5) So local and infused (hormonal) estrogen summate though both ER alpha and ER beta mechanisms to make better LTP in this brain region in females.
6) This predicts that female rats during high estrogen cycle phase (pro estrous) should learn better I a task involving the Schaffer Collaterals than rats in a low estrogen phase (non-protesterous).
What was key finding 3 of the Gall and Lynch study?
Testing behavioral prediction with object location memory. Males and females had an object placed in front of them and were instructed to find it. These objects were then moved around and rats had to find them again. Females in high estrus phase did better than females in low estrus phase.
