Set 5 - Consolidation, Sleep, Stress

Systems consolidation

Gradual reorganization of memories across hippocampal and neocortical networks.

Standard consolidation theory (Squire)

Older memories can become increasingly retrievable through neocortex without hippocampal support.

Multiple trace theory (Nadel/Moscovitch)

Detailed episodic memories keep relying on hippocampus; repeated retrieval establishes multiple traces.

Standard theory — remote-memory prediction

Remote memories may survive hippocampal damage better after extended consolidation.

Multiple trace theory — remote-memory prediction

Rich old autobiographical episodes can remain vulnerable to hippocampal damage.

Semanticization

Contextual detail is reduced while more general factual knowledge or gist remains.

Systems consolidation: key theory test

After hippocampal injury, compare remote detailed recollection with remote factual/gist knowledge.

Hippocampal–neocortical interaction

Distributed cortical features are linked by hippocampal processes during memory formation and recall.

Sleep-dependent consolidation

Sleep supports stabilization of learned information, partly linked to reactivation of neural patterns.

Neural replay

Reappearance of learning-related hippocampal activity sequences during later sleep or rest.

Forward replay during sleep

Learned sequences may reactivate in their original order during sleep.

Reverse replay during wakefulness

Some spatial firing sequences recur in reverse order during awake rest.

Targeted memory reactivation (TMR)

Present learned cues during sleep to preferentially strengthen their associated memories.

Sleep cueing experiment — design

Learn object locations with sounds; replay some sounds during slow-wave sleep, not others.

Sleep cueing experiment — result

Locations linked to replayed sounds were remembered better than uncued locations.

Acute stress and memory

Arousal near learning can enhance memory for salient information, depending on timing and intensity.

Chronic stress and cortisol

Prolonged exposure is associated with impaired hippocampal function and episodic memory.

Glucocorticoid receptors

Receptors through which cortisol can influence hippocampal processing and memory.