Memory consolidation
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Questions and Answers

What occurs during memory reconsolidation?

  • Memories are recalled and then consolidated again. (correct)
  • Memories cannot be strengthened.
  • Memories remain unchanged after recall.
  • Memories are lost permanently.

    • What does cue-dependent amnesia suggest about memory?

  • All memories are equally stable at all times.
  • Memories are never susceptible to disruption.
  • Memories can be disrupted during recall. (correct)
  • Memory is enhanced by electroconvulsive shock.

    • What is an effect of injecting protein synthesis inhibitors into the hippocampus?

  • They prevent emotional memory consolidation.
  • They immediately enhance long-term memory.
  • They have no effect on memory whatsoever.
  • They can disrupt stable long-term memories after a delay. (correct)

    • What happens to a memory while it is in the 'active' state, according to active trace theory?

    <p>It is susceptible to disruption but allows for stronger consolidation. (B)</p> Signup and view all the answers

    Where does memory recall transition from during the consolidation process?

    <p>From the medial temporal lobe to the cortex. (C)</p> Signup and view all the answers

    What characterizes the response of the hippocampus during remote memory tests?

    <p>Activity shifts to different brain regions like the prefrontal cortex. (A)</p> Signup and view all the answers

    Which type of CaMKII is crucial for synaptic consolidation in the cortex?

    <p>Alpha-CaMKII. (B)</p> Signup and view all the answers

    What happens to learned memories in patients with medial temporal lobe damage according to Multiple Trace Theory?

    <p>Episodic memories appear disrupted and are hard to recall vividly. (B)</p> Signup and view all the answers

    What role does the prefrontal cortex (PFC) potentially play in the standard model of memory consolidation?

    <p>It provides inhibitory control over the hippocampus. (B)</p> Signup and view all the answers

    What type of amnesia refers to the inability to form new memories following trauma?

    <p>Anterograde amnesia (A)</p> Signup and view all the answers

    What happens to AMPAR when glutamate activates it during long-term potentiation (LTP)?

    <p>It allows calcium to flow into the cell (B)</p> Signup and view all the answers

    How does protein synthesis affect memory consolidation according to the reviewed content?

    <p>It is critical for long-term memory consolidation (C)</p> Signup and view all the answers

    What does retrograde amnesia typically result in?

    <p>Inability to recall recent memories before trauma (A)</p> Signup and view all the answers

    What model suggests that the hippocampus initially stores memories and later transfers them to the cortex?

    <p>Standard consolidation model (C)</p> Signup and view all the answers

    In the context of memory research, what effect does lesioning the MTL have on memory retrieval over time?

    <p>Older memories remain relatively intact after a longer duration (A)</p> Signup and view all the answers

    What physiological change occurs when NMDA receptors lose their Mg2+ block during LTP?

    <p>Calcium enters the cell (D)</p> Signup and view all the answers

    What is a significant role of the hippocampus in memory processes?

    <p>It helps consolidate memories but does not store them long-term (B)</p> Signup and view all the answers

    Which type of memory is lost due to damage to the medial temporal lobe (MTL)?

    <p>Anterograde memory (C)</p> Signup and view all the answers

    The hippocampus is solely responsible for long-term memory storage.

    <p>False (B)</p> Signup and view all the answers

    What process is disrupted in patients who experience retrograde amnesia?

    <p>The ability to recall memories formed prior to the trauma.</p> Signup and view all the answers

    The activation of NMDA receptors during long-term potentiation (LTP) allows for the influx of __________ ions.

    <p>Calcium</p> Signup and view all the answers

    Match the type of memory loss with its description:

    <p>Retrograde amnesia = Loss of recent memories before trauma Anterograde amnesia = Inability to form new memories after trauma Temporary amnesia = Retrieval failure of memories Storage failure = Permanent failure to access memories</p> Signup and view all the answers

    What role does protein synthesis serve in memory consolidation?

    <p>It supports the long-lasting effects of LTP. (A)</p> Signup and view all the answers

    Hippocampal activity becomes less important for memory retrieval as the memory ages.

    <p>True (A)</p> Signup and view all the answers

    Which model suggests that hippocampal activity is necessary for the initial phase of memory storage?

    <p>Standard Consolidation Model</p> Signup and view all the answers

    What process strengthens synaptic connections between neurons during memory recall?

    <p>Memory reactivation (A)</p> Signup and view all the answers

    Memory reconsolidation occurs only when a memory is recalled and is not affected by cued recall.

    <p>False (B)</p> Signup and view all the answers

    What is the role of CaMKII in long-term potentiation (LTP)?

    <p>Activation of CaMKII initiates cellular changes needed for LTP.</p> Signup and view all the answers

    Memory reconsolidation can be disrupted by __________ if it occurs during the active state of recall.

    <p>electroconvulsive shock</p> Signup and view all the answers

    Which statement about offline replay is true?

    <p>It happens during rest or sleep. (B)</p> Signup and view all the answers

    Match the following terms with their descriptions:

    <p>Memory Reconsolidation = Process of recalling and strengthening long-term memory Active Trace Theory = Concept that active memories are vulnerable to disruption Cue-Dependent Amnesia = Inability to recall memories without specific cues Neurogenesis = Creation of new neurons in specific brain regions</p> Signup and view all the answers

    According to Multiple Trace Theory, episodic memories can be fully recalled without the medial temporal lobe.

    <p>False (B)</p> Signup and view all the answers

    What is indicated by the results of protein synthesis inhibitors injected before and after training?

    <p>That disruptions in memory occur based on the timing of the injection relative to training.</p> Signup and view all the answers

    The hippocampus is one of the few brain areas where __________ occurs.

    <p>neurogenesis</p> Signup and view all the answers

    What phenomenon occurs during memory retrieval that enhances later memory consolidation?

    <p>Memory reactivation (B)</p> Signup and view all the answers

    What is the first step in the process of long-term potentiation (LTP) following glutamate activation?

    <p>Na+ flows into the cell (C)</p> Signup and view all the answers

    Injecting protein synthesis inhibitors 1 hour after training does not disrupt long-term memory until day 7.

    <p>True (A)</p> Signup and view all the answers

    What role does alpha-CaMKII play in synaptic consolidation in the cortex?

    <p>It is crucial for synaptic consolidation.</p> Signup and view all the answers

    Memory recall transitions from the __________ to the cortex during the consolidation process.

    <p>medial temporal lobe</p> Signup and view all the answers

    Match the types of memory tests with their involved brain regions:

    <p>Recent memory test = Hippocampus, basal ganglia Remote memory test = ACC, FC, PC New context test = Hippocampus</p> Signup and view all the answers

    Flashcards

    H.M.'s amnesia

    H.M. experienced a loss of the ability to form new memories (anterograde amnesia), while retaining perceptual and motor skills and memories from before the injury (temporally graded retrograde amnesia).

    Long-Term Potentiation (LTP)

    LTP is a long-lasting strengthening of synaptic connections.

    Synaptic Consolidation

    Memories become stable by making changes in synapses, requiring protein synthesis.

    Amnesia (Retrograde)

    Memory loss for events that happened before a trauma or event; but can remember events from more distant past & can form new memories

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    Amnesia (Anterograde)

    Inability to create new memories.

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    Standard Consolidation Model

    The hippocampus plays a key role in creating new memories, but eventually, these memories are shifted to the cortex for long-term storage.

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    Hippocampus' Role in Retrieval

    Hippocampus plays a vital, even if temporary, role in retrieving memories, specifically recently formed ones.

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    MTL Damage & Amnesia

    Damage to the medial temporal lobe (MTL) can cause both retrograde and anterograde amnesia.

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    Memory Reconsolidation

    The process of recalling a long-term memory and then consolidating it again, leading to its maintenance, strengthening, and updating.

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    Replay (Hippocampus)

    Reactivation of neurons in the same sequence during activity, both during active behavior and rest/sleep. This plays a role in consolidation.

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    Active Trace Theory

    A memory's vulnerability to disruption when in an active/labile state; it can be strengthened during reactivation.

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    Memory Recall (MTL to Cortex)

    The transition of memory from the medial temporal lobe (MTL) to the cortex for long-term storage.

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    Cue-Dependent Amnesia

    A disruption of memory only if it has been reactivated. This supports the reconsolidation theory.

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    Neurogenesis (Hippocampus)

    Creation of new neurons, primarily in the dentate gyrus of the hippocampus, to potentially replace old or unused neurons.

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    Multiple Trace Theory

    The episodic memory in patients with MTL damage is incomplete and flat, suggesting the hippocampus role in episodic experiences.

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    CaMKII's Role

    A calcium-dependent protein kinase involved in long-term potentiation (LTP) of synapses, but its role and type vary between brain regions.

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    Prefrontal Cortex (PFC)

    The PFC's potential role in memory consolidation, possibly by controlling the hippocampus.

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    Replay Ripple (Hippocampus)

    A wave-like electrical activity in the hippocampus during memory consolidation, faster than initial activation.

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    LTP: Pathway

    LTP involves a chain reaction: Glutamate activates AMPA receptors, allowing Na+ to enter and depolarize the cell. This dislodges Mg2+ from NMDA receptors, enabling Ca2+ influx. Activated by calmodulin, CaMKII strengthens the synapse by increasing spine size and recruiting more AMPA receptors.

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    Synaptic Consolidation: Protein Synthesis

    New memories become permanent through structural changes at synapses, requiring protein production. Inhibiting protein synthesis in the hippocampus prevents long-term memory formation and LTP.

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    Retrograde Amnesia

    Loss of memories prior to a trauma, with a tendency to keep older memories intact, while being able to form new ones. Could be caused by permanent memory storage failure or temporary retrieval difficulty.

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    Anterograde Amnesia

    Inability to create new memories after a trauma or event. The brain can't store new information.

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    Hippocampus in Retrieval

    While older memories are thought to be stored in the cortex, the hippocampus is crucial for accessing and retrieving them, especially for recent memories.

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    Standard Consolidation Model: Hippocampus to Cortex

    New memories are initially stored in the hippocampus and then gradually transferred to the cortex, while the hippocampus's role diminishes. Hippocampal involvement in retrieval fades over time.

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    Hippocampus' Role: Importance of Time

    The hippocampus's role in memory consolidation is time-dependent. Early lesions (28 days after learning) don't affect memory, but later ones (100 days) do, supporting the time-dependent transfer to the cortex.

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    Hippocampal Replay Speed

    Replay in the hippocampus is significantly faster than the original experience, up to 20 times quicker.

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    Memory Transition (MTL to Cortex)

    Memories start in the medial temporal lobe (MTL) and gradually move to the cortex for long-term storage. This transition happens over time.

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    CaMKII in LTP

    CaMKII, a protein activated by calcium influx, is involved in long-term potentiation (LTP), but different types might be expressed in the hippocampus vs. the cortex.

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    PFC's Role in Consolidation

    The prefrontal cortex (PFC) might play a role in memory consolidation by potentially inhibiting the influence of the hippocampus.

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    Hippocampus' Role in Memory Transition

    The hippocampus is crucial for initial memory formation and consolidation, but over time memories gradually shift to the cortex for long-term storage.

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    CaMKII's Role in LTP

    CaMKII, activated by calcium influx, is involved in long-term potentiation (LTP) but its specific role and type may vary across different brain regions.

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    Cortical LTP and CaMKII

    The removal of alpha-CaMKII in the cortex disrupts synaptic consolidation, suggesting its importance in cortical learning.

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    Hippocampus vs. Cortex: Learning Speed

    The cortex learns more slowly than the hippocampus, potentially due to different mechanisms and roles of CaMKII in these regions.

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    Engram

    A population of neurons activated during learning, undergoing enduring cellular changes (plasticity), and reactivated by the original stimulus for memory recall.

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    How do we label active engrams?

    By using DOX, a TRE inhibitor, to block the expression of genes like ChR2 or ArchT, which are activated in response to the FOS promoter upregulation. When DOX is removed, only those neurons that were actively involved in learning will express these genes, allowing us to identify them.

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    Silent Engrams

    Engrams that are not activated by natural cues but can be artificially activated. They are active during recall but not enough to evoke the memory.

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    mPFC Role in Memory Recall

    The mPFC plays a crucial role in the retrieval of both recent and remote memories. It acts as a crucial hub for accessing stored information.

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    Inhibition of BLA input to mPFC

    Inhibition of the BLA's projections to the mPFC during learning reduces the number of c-Fos neurons in the mPFC during contextual fear conditioning. This suggests that the BLA plays a critical role in shaping the fear memory in the mPFC.

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    Study Notes

    Human Memory (H.M.)

    • Perceptual and motor skills remain intact
    • Ability to form new memories is disrupted
    • Loss of declarative memory (episodic and semantic)
    • Memory intact for up to 11 years before the accident
    • Then, memory gradually fades back to the accident, demonstrating temporally graded retrograde amnesia

    Long-Term Potentiation (LTP)

    • Glutamate activates AMPA receptors, allowing sodium influx and depolarization
    • Depolarization removes magnesium block from NMDA receptors, allowing calcium influx
    • Calcium activates calmodulin, leading to CaMKII activation
    • CaMKII triggers actin breakdown and spine enlargement, promoting AMPA receptor recruitment
    • PKA and CREB are activated, leading to mRNA production and protein synthesis, essential for synaptic plasticity
    • Protein synthesis inhibitors block memory consolidation in the hippocampus
    • These inhibitors prevent long-term LTP.
    • Glutamate activation of AMPA receptors leads to sodium inflow, cell depolarization, and NMDA receptor unblocking, allowing calcium inflow, and activating calmodulin. This leads to CaMKII activation, actin breakdown, spine enlargement, AMPA recruitment, PKA, CREB, and finally mRNA production for protein synthesis, fostering synaptic plasticity.

    Amnesia Due to Medial Temporal Lobe (MTL) Damage

    • Amnesia encompasses impaired memory and learning
    • Retrograde amnesia involves loss of memories before the trauma but preserved long-term memories
    • Storage failure: Permanent loss of memories due to disruption
    • Retrieval failure: Temporary difficulty in recalling memories, potentially due to damage in pathways
    • Anterograde amnesia denotes the inability to create new memories
    • Retrograde amnesia can range from recent to distant memories, depending on the time since the brain injury.
    • Anterograde amnesia specifically involves an inability to store new declarative memories.
    • Older memories may be stored elsewhere if not in the MTL.
    • Storage/retrieval failures in the MTL can affect the ability to retain or recall memories from different periods.

    Where are Older Memories Stored?

    • Hippocampal involvement is crucial for retrieving memories
    • Contextual fear conditioning studies in animals help to infer the memory retrieval mechanisms
    • Hippocampal lesions can impair the retrieval of contextual memories.
    • Damage to the hippocampus can affect memory retrieval, even for memories acquired long before the injury, depending on the timing of the lesion.
    • Retrograde amnesia can be fully intact depending on the timing of the lesion (e.g., Kim & Fanselow for 28 days, Maren for 100 days, Anagnostaras for 50 days).
    • Different studies have shown varying results regarding the extent of retrograde amnesia depending on the time elapsed between the injury and memory testing.

    Standard Consolidation Model

    • David Marr proposed that the hippocampus rapidly acquires memories and subsequently transfers them to the cortex
    • Forward replay: Neurons activate in the same sequence as the original experience
    • Reverse replay: Neurons activate in the reverse order of the original experience
    • Hippocampal activity is initially vital, with strong connections, subsequently becoming weaker, as memories transition to the cortex (where stronger connections ultimately form).

    Memory Reconsolidation

    • Memory reactivation during consolidation strengthens synaptic connections
    • This process is crucial for the maintenance, strengthening, and updating of long-term memories
    • Cue-dependent amnesia shows the vulnerability of reactivated memories to disruption through either external electrical stimulation (ECS) or other conditioning procedures.
    • Memory reactivation makes memories accessible and sensitive to disruption and alteration. Memory reconsolidation encompasses processes where a long-term memory (LTM) is recalled and re-consolidated, affecting its persistence. Memories can be reactivated due to replay or cued recall.

    Active Trace Theory

    • An active memory is susceptible to disruption but also allows for stronger consolidation
    • Recall of a memory strengthens the memory trace and transitions from hippocampus to cortex
    • Consolidation transfers it to the cortex, making it less vulnerable
    • The memory is most vulnerable during transfer to the cortex.

    Protein Synthesis Inhibitors in Hippocampus

    • Protein synthesis inhibitors in the hippocampus impair stable long-term memories.
    • Disruptions are observed hours later and are long-lasting, suggesting a crucial role of protein synthesis in memory consolidation. Protein synthesis inhibitors can disrupt long-term memories by affecting consolidation, potentially early or short term.

    Multiple Trace Theory

    • Suggests that episodic memories are initially stored, and subsequently transferred to the cortex. However, unlike the standard consolidation model, this theory emphasizes that not all memories are entirely moved from the hippocampus. All memories, including their original traces, are retained.

    Prefrontal Cortex Involvement

    • Prefrontal cortex may exert inhibitory control over the hippocampus, impacting memory consolidation.
    • Prefrontal cortex may play a role in modulating hippocampal activity during memory consolidation, influencing memory traces.

    Neurogenesis

    • Hippocampal neurogenesis (new neuron creation) plays a critical role in memory formation, potentially impacting both memory consolidation and retrieval.
    • New neurons can be created in the hippocampus dentate gyrus. Old or unused neurons are shed.
    • CaMKII has different effects in different brain regions (hippocampus vs. cortex), potentially impacting learning rates. Brain regions can be differentially affected depending on factors such as the types of experiences and their intensities.

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    Memory Consolidation PDF

    Description

    Test your knowledge on key concepts of human memory, including the role of long-term potentiation (LTP) and the impacts of medial temporal lobe damage on memory formation. Explore how mechanisms like AMPA and NMDA receptors relate to memory and synaptic plasticity. This quiz covers crucial aspects of memory function and impairment.

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