The Memory Function of Sleep

1. The Memory Function of Sleep Group 1 Amanda Ayoub Hannah Stolarczyk Stephanie Regan Alicia Iafonaro

2. 1. What is memory consolidation? • Process that encodes new memories so they can be retrieved later in time • Two specific processes for memory consolidation • Synaptic consolidation: occurs the first few hours after learning • System consolidation: memories that are dependent on hippocampus become independent over period of weeks or years

3. 1. What kinds of memory are consolidated in sleep? • Declarative (explicit) and Procedural (implicit) memories, as well as emotional information, consolidated during sleep • Retention of declarative information • Improvement in performance of procedural tasks

4. 2. What are examples of implicit and explicit learning, and how are they connected with consolidation during sleep? What else is known about what sort of memory is best consolidated? • Encoding of declarative memories (facts) is typically explicit, whereas procedural memory (how do to something) encoding can involve both implicit and explicit processes. • Sleep benefits are greater for memories formed from explicitly encoded information that was more difficult to encode or previously weakly encoded. It also has a higher benefit for memories relevant to behavior.

5. 2. Cont. • Sleep enhances the consolidation of memories for intended future actions and plans. • Several studies indicate that sleep helps consolidation in all major memory systems, but it generally favors memories explicitly encoded and relevant to behavior

6. 3. Describe what happens to memory representations during sleep. Discuss related findings from studies in some detail. What conclusions can be drawn? • Sleep reorganizes newly encoded representations. This enables the development of new associations and extracts invariant features from complex stimuli. • Also allows memory representations to convert from implicit to explicit knowledge.

7. 3. Cont. • Contrasting, it’s thought that memory systems compete and reciprocally interfere during waking, and disengage during sleep allowing for consolidation to take place in the different systems. • There may be a sequential contribution of interaction and disengagement during consolidation during the different stages of sleep

8. What is meant by different memory “systems,” and what is going on with them in the context of this article? • Memory systems – different types of memory • Declarative (Explicit) • Non-declarative (Implicit) • Different memory systems are thought to be mediated by distinct neural systems

9. In humans, SWS and REM sleep dominate the early and late part of nocturnal sleep SWS-rich, early sleep consistently benefits the consolidation of declarative memories REM-rich sleep benefits non-declarative types of memory (procedural and emotional aspects of memory) 5. Discuss, with some completeness, what the article has to say about sleep stages and consolidation. Include findings for animals and humans. In this, the importance of REM, SWS, REMD should be discussed. • The sleep stages are: • REM (rapid eye movement) • REMD (REM sleep deprivation) • SWS (slow-wave sleep) or deep sleep

10. 5 Continued... • These results are consistent with the ‘dual-process hypothesis’ • SWS supports declarative, hippocampus-dependent memory • REM sleep supports non-declarative, hippocampus-independent memory. • Happens when SWS and REM take place in succession.

11. 5 Continued... • In rats, showed that REMD is only effective during specific periods after learning the “REM sleep windows” • During post learning sleep, the amount and intensity of REM sleep increases even several hours or even days after learning, depending on the kind of task and amount of initial training • Memory is particularly impaired if REMD coincides with these periods. • Evidence shows that REM sleep favors the consolidation of emotional aspects of a memory (could account for the strong REMD effect observed)