Lecture 11A: Emotional Memory and Engrams

Question 1

what is the main premise of this lecture

Answer 1

visualizing and manipulating fear memory in relation to the engram

Question 2

explain the pathway for fear conditioning

Answer 2

once the conditioning stimuli is given, the sensory thalamus (lateral) sends neurons and signals to the lateral amygala and this connection is where that memory is formed for fear conditioning

Question 3

what is significant about the pathway between sensory thalamus and lateral amygdala

Answer 3

this is where we expect potentiation to occur which is how memory is formed (Uses LTP)

Question 4

what structure is involved in fear conditioning

Answer 4

lateral amygala

Question 5

explain the auditory fear conditioning experiment

Answer 5

put rat in a chamber, apply a tone and then shock them so that they start to associate the tone with a shock and will freeze when only given the shock

then move them to a different chamber that is the exact same but not associated with the shock, then you play only the tone and measure the level of freezing which shows fear and how well they remembered this experiment

Question 6

explain the process of LTP (9)

Answer 6

1. action potential reaches the end of the synapse
2. glutamate gets released and binds to AMPA and NMDA receptors
3. once the post synaptic neuron reaches a specific level of deactivation, the NMDA receptor will get rid of the Mg2+ that is blocking the channel
4. calcium then is able to go into the cell which is a key step in the cascade of events
5. Ca2+ activates adenyl cyclase
6. adenyl cyclase activates cAMP
7. cAMP activates PKA
8. PKA activates CREB
9. CREB activates specific pathways in the nucleus in order to create proteins and is also involved in-the potentiation that is necessary for learning and memory

Question 7

define engram

Answer 7

enduring offline physical and/or chemical changes that were caused by learning and underlie newly formed memory associations

specific neurons or cell assemblies

Question 8

what were the 3 main goals for the 3 experiments

Answer 8

1. imagine and influencing the engram (label)
2. erasing the engram
3. inducing memory recall

Question 9

what was the main way that they tested the imaging and influencing of CREB to fear memories

Answer 9

looking at the association and influence of creb to fear memories

Question 10

is creb activated in the LA

Answer 10

yes, CREB is activated in the lateral amygdala after a cued fear memory induing protocol

Question 11

do CREB deficient mice show fear memory and what does this result show

Answer 11

no, CREB deficient mice did not learn or remember the task

this shows that CREB must be activated so the mice can learn the task

Question 12

what do CREB viral infections show

Answer 12

that these infections target about 20% of lateral amydgala neurons

Question 13

what did the injection of CREB viral infections show

Answer 13

CREB viral infections are only showing deficits in memory deficient mice

Question 14

what did the CREB vector injection show

Answer 14

creb infected neurons are more likely to be incorporated into cue induced fear memories than control

more likely to show fear conditioning

Question 15

does the CREB infection procedure do anything when it is not paired with training

Answer 15

no, no training does not show anything different.

Question 16

does super CREB do anything without training

Answer 16

no, even the version that self phosphorylates doesnt do anything anatomically

Question 17

what does injecting crappy CREB before training show

Answer 17

it neither improves or impairs memory, kinda does nothing as it is an inactive form

Question 18

what is the outcome/summary of the imaging and influencing engram experiment

Answer 18

memory trace does not change size, but the proportion of neurons incorporated increases with good CREB infections in the lateral amydgala

Question 19

is CREB activation in the lateral amygdala correlated with auditory fear conditioning

Answer 19

yes

Question 20

what does the constant size of memory trace suggest

Answer 20

competitive selection process that is bias on CREB activity

only thing that changes is the neurons

Question 21

what is the main premise of the erasing engram experiment

Answer 21

first was to label the engram, then kill the cells, will this erase the memory?

Question 22

what was the experimental design for erasing the engram

Answer 22

1. surgery - inject with creb and also with something that will kill the neurons that are associated with creb
2. wait 2 days after surgery and then train with tone
3. wait 24h after train and then test 1
4. inject with DT (diphilia toxin)
5. wait 2 days after tone and test 2

Question 23

what was the expectation for the erasing engram experiment

Answer 23

the memory would be erased

Question 24

what was the result of the erasing engram experiemnt

Answer 24

after creb and cre, the freezing percent was lower, showing that the mice did not remember the task

Question 25

what was the result of the erasing engram experiment

Answer 25

by targeted killing of the lateral amydgala neurons that have been biased into the engram, one can erase the cued fear memory

Question 26

what is the premise of inducing memory recall

Answer 26

if you activate the neurons, will the rat freeze without even hearing the tone

Question 27

explain the experiment for inducing memory recall

Answer 27

inject with creb and then give TRPV1, which is normally in tongue for feeling spice, and then give capsacin which will bind to TRPV1 and activate those cells to induce recall

or combined TRPV and CREB expression conducted prior or after training shows that creb infected cells will be biased into memory trace only when infected prior to training

Question 28

what was the outcome of the inducing memory recall experiment

Answer 28

chemogentic expression does not change waveform properties of spiking LA neurons but it does increase their firing rate when the ligand is present

whenever capsacin is injected into the cells w receptors, it fires

reactivation of targeted neurons in LA supports memory recall of cued fear