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Questions and Answers
What role do engrams play during the learning process?
What role do engrams play during the learning process?
What is the primary function of the FOS promoter in relation to engrams?
What is the primary function of the FOS promoter in relation to engrams?
During the memory consolidation process, which structure directly receives output from the hippocampus?
During the memory consolidation process, which structure directly receives output from the hippocampus?
What happens when DOX is removed in the context of labeling engrams?
What happens when DOX is removed in the context of labeling engrams?
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What is the role of blue light in the fear expression experiment?
What is the role of blue light in the fear expression experiment?
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What did the results of Experiment 1 suggest regarding the role of the mPFC in recent memory recall?
What did the results of Experiment 1 suggest regarding the role of the mPFC in recent memory recall?
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What does the c-FOS expression indicate in the context of memory processing?
What does the c-FOS expression indicate in the context of memory processing?
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What impact does inhibiting BLA projections to the mPFC have during contextual fear conditioning?
What impact does inhibiting BLA projections to the mPFC have during contextual fear conditioning?
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What is necessary for the formation of the fear engram in the mPFC?
What is necessary for the formation of the fear engram in the mPFC?
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Which observation supports the reactivation of engram cells on day 13?
Which observation supports the reactivation of engram cells on day 13?
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What happens when the mEC inputs to the mPFC are inhibited on Day 1?
What happens when the mEC inputs to the mPFC are inhibited on Day 1?
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What role does the mPFC play in the fear memory after 12 days of consolidation?
What role does the mPFC play in the fear memory after 12 days of consolidation?
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What did the inhibition of the engram on Day 2 indicate about fear expression?
What did the inhibition of the engram on Day 2 indicate about fear expression?
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What is the role of spine growth in tagged neurons following fear conditioning?
What is the role of spine growth in tagged neurons following fear conditioning?
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Which statement about c-Fos+ neurons is true regarding context-recall?
Which statement about c-Fos+ neurons is true regarding context-recall?
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How does stimulating tagged c-Fos+ neurons affect memory retrieval?
How does stimulating tagged c-Fos+ neurons affect memory retrieval?
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What happens when the blue light is turned on in the fear expression experiment?
What happens when the blue light is turned on in the fear expression experiment?
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The hippocampus is primarily involved in the recall of remote memories.
The hippocampus is primarily involved in the recall of remote memories.
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What is the effect of inhibiting mEC projections to the mPFC during learning?
What is the effect of inhibiting mEC projections to the mPFC during learning?
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The primary regions involved in the generation of memory circuits are the hippocampus, medial entorhinal cortex, ___, and ___.
The primary regions involved in the generation of memory circuits are the hippocampus, medial entorhinal cortex, ___, and ___.
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Match the engram activation elements to their effects:
Match the engram activation elements to their effects:
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During memory consolidation, which pathway is primarily involved when recalling memories after a long term?
During memory consolidation, which pathway is primarily involved when recalling memories after a long term?
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Removal of DOX leads to the labeling of inactive engrams.
Removal of DOX leads to the labeling of inactive engrams.
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What does high c-FOS expression in the PFC following shock in a specific context indicate?
What does high c-FOS expression in the PFC following shock in a specific context indicate?
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What is the main finding regarding the involvement of mEC inputs in the formation of the fear engram in the mPFC?
What is the main finding regarding the involvement of mEC inputs in the formation of the fear engram in the mPFC?
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The inhibition of mPFC on Day 12 results in a significant recall of fear memory.
The inhibition of mPFC on Day 12 results in a significant recall of fear memory.
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What occurs in mPFC neurons when the fear engram is consolidated?
What occurs in mPFC neurons when the fear engram is consolidated?
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The early consolidation of fear memory occurs in the _______ before it is completely stored in the mPFC.
The early consolidation of fear memory occurs in the _______ before it is completely stored in the mPFC.
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Match the following days with the relevant findings regarding the fear engram activation:
Match the following days with the relevant findings regarding the fear engram activation:
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What is suggested by the presence of active tagged c-Fos+ neurons during context-induced recall?
What is suggested by the presence of active tagged c-Fos+ neurons during context-induced recall?
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Inhibition of the mEC to mPFC pathway during CFC enhances the consolidation of fear memory.
Inhibition of the mEC to mPFC pathway during CFC enhances the consolidation of fear memory.
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What technique is used to stimulate the tagged neurons in the engram study?
What technique is used to stimulate the tagged neurons in the engram study?
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What happens to silent engrams in the mPFC during contextual fear conditioning?
What happens to silent engrams in the mPFC during contextual fear conditioning?
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The mPFC is involved in the recall of both recent and remote memories.
The mPFC is involved in the recall of both recent and remote memories.
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What does c-FOS indicate in the context of memory processing?
What does c-FOS indicate in the context of memory processing?
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Removal of _______ allows for the labeling and activation of active engrams.
Removal of _______ allows for the labeling and activation of active engrams.
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Match the following memory pathways with their corresponding functions:
Match the following memory pathways with their corresponding functions:
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Which action can inhibit freezing behavior during memory recall?
Which action can inhibit freezing behavior during memory recall?
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Engrams are only active during memory recall and not during the learning process.
Engrams are only active during memory recall and not during the learning process.
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What can be concluded from the inhibition of the mEC to mPFC pathway during CFC?
What can be concluded from the inhibition of the mEC to mPFC pathway during CFC?
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The majority of memory integration occurs in the _______ during consolidation.
The majority of memory integration occurs in the _______ during consolidation.
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Which of the following states describes the state of engrams in the mPFC shortly after contextual fear conditioning?
Which of the following states describes the state of engrams in the mPFC shortly after contextual fear conditioning?
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Study Notes
Engrams
- Engrams are neuron populations activated during learning.
- They exhibit enduring cellular changes (plasticity).
- Engrams are reactivated by the original learning stimulus.
Turning Engrams On/Off
- Transcription factor c-FOS is a product of plasticity and is induced when neurons are activated to bing to Transcriptional Response Elements (TREs).
- The expression of the protein ChR2 results in activation while ArcheT inhibits the activation.
- DOX inhibits TREs, so by removing DOX, active engrams can be labelled.
- Light can be used to turn engrams on or off. Blue light turns engrams on, while yellow light inhibits them.
- Removal of DOX labels active engrams.
Memory Consolidation Circuits
- Engrams form in a circuit from the hippocampus to the medial entorhinal cortex (MEC) to the mPFC and BLA.
- Memories are consolidated, shifting from the hippocampus to cerebral cortex.
- Recent memories rely on the hippocampus, while remote memories do not. Consolidation occurs, involving transfer of the engram to cortex for permanent storage.
Recall
- Recent memory recall involves a hippocampus to BLA pathway.
- Remote memory recall bypasses the hippocampus using the mPFC and BLA. Early memory relies on the hippocampus, but later memory is stored in the cortex.
Fear Conditioning
- Hippocampal engrams are sufficient for fear expression.
- Methods include: context A with DOX, a second fear-conditioning context with DOX, and returning to the first context with light.
- Light activation of the hippocampus engram leads to fear reactivation in new contexts. The hippocampus is necessary for the initial fear conditioning.
Inactivation of Entorhinal Cortex Projections
- Injecting a virus with ChR2 into the MEC, inhibiting mEC terminals in the mPFC, while implanting optical fibers in the mPFC impacts recent memory recall.
- Disrupting the mEC projections to the mPFC affects recall of recent memory, but not remote memory. The mEC pathway is important for forming recent memories.
mPFC Activity
- Some mPFC cells play a role in early memory, but are not sufficient to support subsequent memories as memories move to the cortex.
- mPFC activity increases when a context includes shock.
- Inactivation of BLA projections to mPFC during learning reduces c-FOS in contextual fear-conditioning situations. The BLA is necessary for some early activity in the mPFC.
Engram Sufficiency
- A subset of c-FOS-positive mPFC neurons experience plasticity during learning depending on inputs from the BLA and mEC to form an engram.
- Injecting ChR2 to activate engrams in the mEC leads to increased fear reaction.
- Activation of mPFC engrams is crucial for fear conditioning memory consolidation. The mPFC is critical for the long-term storage of the fear engram
Silent Engrams
- Engrams can be in a "silent" state initially.
- Engrams are not activated by natural cues, but only artificially.
- Engrams in the mPFC are silent after contextual fear conditioning, and can be reactivated by light. Memory reactivation, or reconsolidation, can occur. Repeated activation strengthens these engrams.
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Description
Explore the fascinating world of engrams and their role in memory consolidation. This quiz covers the activation and inhibition mechanisms of engrams, the circuits involved in memory formation, and the importance of light in memory manipulation. Test your knowledge on how these processes shape our understanding of learning and memory.
