Exam 4: Chapters 15-17 Flashcards
Describe the destabalization function.
The claim was that retrieving a memory returned it into a labile state that made it vulnerable to disruption.
Describe the integrative function.
The role of the brain is to assess new content and integrate it with previously acquired information represented in the engram, which results in a new engram that contains both the retrieved and new information.
How did ECS after reactivation affect memory?
ECS after reactivation of the CS memory blocked the memory.
What did Donald Lewis propose?
Proposed that memories in an active state are more vulnerable to disruption than memories in an inactive state.
What are the specific assumptions about the active trace theory?
- Novel experience can create an active STM trace that will decay into the inactive LTM state
- Retrieval cues can retrieve an inactive LTM trace and place it in the active state that then will decay into the inactive LTM state
What did Susan Sara’s NMDA experiments show?
After reactivating a memory, LTP mechanisms are reengaged, w/in 90 min of reactivitng a memory it is dependent on intact NMDA receptors in order for it to endure
What was Nader’s finding?
How does anisomycin affect memory?
Anisomycin (protein synthesis inhibitor) disrupted the LTM retention of the reactivted fear memory but had no effect on the short-term retention of the memory.
What are the implications of reconsolidation theory?
- Retrieval weakens or unbinds synapses underlying memory trace
- Retrieval also intiates another round of protein synthesis so that the trace is “reconsolidated”
How does reactivation destablaize the trace?
Describe the flow diagram.
Anisomycin infused prior to reactivation normally produces amnesia,
What happens when you inhibit the proteasome?
Inhibiting proteasome function prevented destabilization of the synapses and protected against anisomycin-produced amnesia.
When you inhibt the proteasome it prevents the need for new protein
What is a prediction error?
Positive vs. negative
Prediction errors occur when expectations are not met.
Negative: the world works worse than you thought
Positive: the world works better than you thought
Describe the prediction error experiment.
How did anisomycin affect the result?
Animals were conditioned with a shock 30 sec after a tone. Animals made a prediction error when the shock was delivered after 10 sec, because they were predicting 30 sec. Creating the prediction error destabilized the engram so that anisomycin resulted in reduced fear.
What does additional learning depend on?
How do we know this?
Additional learning normally produced by a second conditioning trial requires that the trace be destabilized because inhibiting proteasome activity prevetns the additional learning.
What was the Nader AMPA Inhibition Amygdala Experiment?
CNQX prevented the expression of the freezing response when the engram was reactivated, but fear memory persisted at test. However, anisomycin still produced amnesia on the test. Thus, the engram destabilized without the behaviroal expression of the memory at reactivation.
CNQX is an AMPA antagonist
What were the results of the Nader NMDA inhibition experiment?
An NMDA antagonist did not interfere with the expression of the freezing response when the engram was reactivated, but it did prevent the amnesia normally produced by anisomycin.
What are the 3 conclusions made from the Nader experiments?
- The engram destabilizes even if the behavior does not occur when the engram is reactivated.
- Calcium-dependent processes initiated via NMDA receptors are essential to destabilize the engram.
- Fear engrams exsist independent of its ability to generate behavior
In the integration theory, what is the encoding specificity principle?
When does a retrieval failure occur?
Successful memory retrieval depends on a match between the retrieval cues and the environmental stimulation encoded into the engram.
A retrieval failure occurs when key retrieval cues are missing.
What is state dependent learning?
Cues generated by our internal state at the time of a learning experience can become part of the engram. These internal state cues need to be present at the time of retrieval to awaken the engram.
What is the fundamental difference between reconsolidation theory and active trace theory?
Reconsolidation theory says that the act of retrieval is enough to disrupt an already established memory, but active memory trace theory says that retrieval makes a consolidated memory vulnerable to disruption due to other agents.
According to the integration theory why does anisomycin produce amnesia?
When anisomycin is administered following reactivation of the memory, the internal conditions it produces become part of the engram. If retrieval were to be possible, then anisomycin would need to be administered.
Anisomycin therefore does not produce amnesia because it caused a storge failure but rather a retreival failure because the internal state during test were not present during reconsolidation.
What is a potential therapy for preventing relapse by interfering with reconsolidation?
Zif268 antisense prevented the reconsolidation of the drug memory associated with the CS.
What is the multiple memory system perspective?
A complete understanding of memory can only be achieved by recognizing that the content of experience is important and that memories are segregated into different brain regions according to their content.
What is pattern completion?
During memory retrieval, when a subset of the initial input pattern activates the hippocampal index, output from the hippocampus projects back to the neocortex to activate the original neocortical pattern.
