Targeted Memory Reactivation
The firing rates of hippocampal neurons during behaviour tend to be correlated with firing rates of the same neurons during subsequent sleep
Neurons that fired together during behaviour were more likely to fire together during non-REM sleep
Replays occur 5–20 times faster than actual events
Hippocampal replay can be accompanied by cortical replay of the same event
Manipulating sharp wave ripples such that replay is suppressed (or enhanced) results in impairment (or improvement) in memory consolidation
Targeted Memory Reactivation: manipulate reactivation on demand
TMR influences what is replayed, but doesn’t increase the total number of replays
TMR benefits to cued memories come at the cost of weaker non-cued memories
TMR may effectively trick the hippocampus by evoking what looks like a spontaneous reactivation of a memory in cortex and in turn influence what the hippocampus replays
Because the hippocampus encodes spatiotemporal context, while other aspects of the memory such as emotional valence and sensory components are encoded in cortex, the reverberation of a replay event helps bind these different components together to form a coherent memory
A cortical memory representation reactivates during the ‘up’ state of a slow oscillation and triggers a hippocampal replay of the same memory, allowing integration of this information across space and time
This integrated representation is then sent back to the cortex for a second reactivation, with the repetition of this pattern potentially creating a series of temporally spaced hippocampal-cortical re-activations
Memory triage is a sleep-dependent process by which memories with perceived future relevance are prioritized for consolidation
Repeated replay events could gradually decrease the strength of the ‘tag’ associated with a cortical network, thus decreasing that network’s excitability
Create a prioritization trade-off between how many times a memory has been replayed and its salience relative to other recent memories
Form a critical feedback mechanism for the memory triage process
The firing rates of hippocampal neurons during behaviour tend to be correlated with firing rates of the same neurons during subsequent sleep
Neurons that fired together during behaviour were more likely to fire together during non-REM sleep
Replays occur 5–20 times faster than actual events
Hippocampal replay can be accompanied by cortical replay of the same event
Manipulating sharp wave ripples such that replay is suppressed (or enhanced) results in impairment (or improvement) in memory consolidation
Targeted Memory Reactivation: manipulate reactivation on demand
TMR influences what is replayed, but doesn’t increase the total number of replays
TMR benefits to cued memories come at the cost of weaker non-cued memories
TMR may effectively trick the hippocampus by evoking what looks like a spontaneous reactivation of a memory in cortex and in turn influence what the hippocampus replays
Because the hippocampus encodes spatiotemporal context, while other aspects of the memory such as emotional valence and sensory components are encoded in cortex, the reverberation of a replay event helps bind these different components together to form a coherent memory
A cortical memory representation reactivates during the ‘up’ state of a slow oscillation and triggers a hippocampal replay of the same memory, allowing integration of this information across space and time
This integrated representation is then sent back to the cortex for a second reactivation, with the repetition of this pattern potentially creating a series of temporally spaced hippocampal-cortical re-activations
Memory triage is a sleep-dependent process by which memories with perceived future relevance are prioritized for consolidation
Repeated replay events could gradually decrease the strength of the ‘tag’ associated with a cortical network, thus decreasing that network’s excitability
Create a prioritization trade-off between how many times a memory has been replayed and its salience relative to other recent memories
Form a critical feedback mechanism for the memory triage process
