W8 - Fear 1/2 Flashcards
What is the major limitation to extinction therapy?
extinction is not permanent and fear/anxiety will relapse
Research shows that the fear memory can return after extinction, what does that imply for the encoding of fear memories?
extinction is new learning, and is not the erasure of the original fear memory
What is the difference between renewal and reinstatement?
reinstatement: following extinction, re-exposing animals to the reinforcer (i.e. foot-shock) will lead re-expression of the original fear memory
renewal: following extinction of a cue-shock association in one context, the fear memory reappears when animals are later tested for fear to the cues to the original training context
Which grain region in known to be involved in the memory storage of contextual fear?
Dentate gyrus sub-region of the hippocampus
Can sparsely activated ensembles of cells form an engram?
Yes
What was known about optogenetic activation/inhibition of fear engrams before the study of Lacagnina et al.? What did this group want to answer?
Optogenetically stimulating fear engrams increases freezing after forgetting or amnestic treatments
Optogenetically inhibiting fear engrams suppresses freezing
Fear engrams in the DG are important for fear memories but how does extinction training
change the activity of fear engrams?
What is the main utility of ArcCre mice?
can be used to ‘tag’ cells that are active within a specific time window
In the study of Lacagnina et al., under which condition is Cre becoming active?
When it fuses with an estrogen receptor derived from tamoxifen (administered to the mice at the time of fear recall/extinction)
Lacagnina et al. report that extinction reduces activity of fear engrams. On which observation is this based?
Extinction reduces the number of fear acquisition tagged cells that are active in the conditioned stressful context, compared to mice that did not undergo extinction
How are fear extinction and acquisition engrams differently activated during extinction?
Reactivation of fear and extinction engrams suggests that the fear engram is suppressed in favour of the extinction engram during extinction
How are fear extinction and acquisition engrams differently activated spontaneous recovery of fear?
When spontaneous recovery occurs, the extinction engram is less active and the fear engram is more active
What happens when extinction engrams are optogenetically silenced?
Silencing extinction memories increases freezing at short but not long delays
What happens when spontaneous recovery engrams are optogenetically silenced?
Silencing fear memories reduces spontaneous recovery (freezing)
Why is it that, at longer delays, the activation of fear acquisition engrams is facilitated?
At longer delays, spontaneous recovery of fear is associated with reduced activity of extinction
engrams and increased activity of fear engrams
