1. Sleep and Memory: Overview
Rachel Miriani
Neural Systems
Nov 29, 2004

2. Introduction to Memory
“The mental faculty of retaining and recalling past experiences; the ability to remember.”1
Has many different forms of classification
The most common being divided into declarative & non-declarative memories.

3. Introduction to Memory
Declarative
Non-Declarative
“Consciously accessible memories of fact-based information”- The What.
Non-conscious
Declarative: things you consciously learn: mathematics, football games, your parents and their names, the first time you are learning dance steps.
*Non-Declarative: things you learn and recall subconscously: walking, word articulation.

4. Introduction to Memory
Declarative
Non-Declarative
What.
Non-conscious
Episodic
Semantic
Not event specific general knowledge
Experiences and events from ones past.
This declarative “what” category can further be broken into Semantic and Episodic learning.
Episodic: Thanksgiving dinner this year, your 16th birthday, your family vacation to Disney World.
Semantic: Calculus, vocabulary

5. Introduction to Memory
Declarative
Non-Declarative
What.
Non-conscious
Episodic
Semantic
Non declarative:
Explicit: Procedural Skills:
Implicit learning:
Conditioning
Non-associative:
Priming:
Procedural Skills
Conditioning
Non-associative
Priming

6. Introduction to Memory
Declarative
Non-Declarative
What.
Non-conscious
Episodic
Semantic
Although the definitions are relatively clear cut it is very rare that a situation/experience would only utilize one or the other
Ex: Language learning
Non-declarative: procedural- motor programs to speech articulation (how to shape your lips and tongue to form the “oooo” sound); **-grammatical rules and structure.
Declarative: Semantic- word selection
Procedural Skills
Conditioning
Non-associative
Priming

7. Introduction to Sleep: REM
NREM
REM: Rapid Eye Movement
Muscle tone decreases.
EEG oscillations are desynchronized
Gamma waves appear Hz synchronous activity is similar to being awake.
Periodic bursts of rapid eye movement.
PGO waves appear- Phasic endogenous waveforms expressed in the pons (P), lateral geniculate nuclei of the thalamus (G), and the occipital cortex (O).
Stages
Picts of gamma waves PGO REM bursts
Locale and wakeful function of pons lateral geniculate nuclei of the thalamus

8. Introduction to Sleep Sleep REM NREM Stages 1 2 3 4
Stage 2 characteristically has phasic electrical events:
*K Complexes- Large electrically sharp EEG waves
*Sleep Spindles- Short 7-14 Hz synchronized oscillations in the EEG
Stages
*Increasing depth of sleep
*EEG frequency slows down
Pict and better descript of Kcomplexes and sleep spindles

9. Introduction to Sleep Sleep REM NREM Stages 1 2 3 4
Stages 3 and 4 are typically grouped together and dubbed Slow Wave Sleep (SWS) due to the low frequency waves (0.5-4 Hz and <1Hz) caused by cortical synchrony
Increasing depth of sleep
EEG frequency slows down
Picts and a bit more physiological desc. Of deep sleep
Picts of SWS

10. 1 Cycle of REM and NREM takes ~90mins
Ratio of REM to NREM changes with each cycle
Initially 3&4

11. Sleep Cycles One cycle of NREM and REM sleep takes ~90 mins
Ratio of NREM/REM per cycle changes during the night
Initially Stages 3 and 4 of NREM sleep dominate
Near the end of the night REM and stage 2 sleep dominate the cycles

12. Sleep Stages Beta waves:+14Hz Alpha waves: 7.5-13Hz
Symmetrical distribution and most apparent in the frontal lobe.
Rapid, irregular, and low voltage
Alpha waves: Hz
Best seen on the posterior sides the head but stronger on the dominant side.
Stops when eyes open or alerting by any mechanism (thinking)
Theta waves: Hz
Sleep Spindles: 7-14 Hz
Short bursts of high frequency activity
Assumed to be responsible for keeping the individual asleep
K-complexes:
short burst of high amplitude activity
Probably the precursors to delta activity
Delta waves: <4Hz
Highest amplitude, slowest waves
PGO waves:
Associated with increased visual system excitability but arise spontaneously
Influenced by auditory and somatosensory stimuli
Generated in the pontine brain stem

13. Neurochemistry Neurochemistry changes with sleep stages
NREM
Significant drop in activity of subcortical cholinergic systems
Reduction in firing rate of aminergic populations
REM
Significant increase in activity of subcortical cholinergic systems
Significant inhibition of aminergic populations
REM sleep is dominated by acetylcholine and essentially absent of aminergic modulation
Aminergic populations: serotonergic raphe neurons and noradrenergic locus coeruleus neurons

14. Developing a Memory
Integration: associating new info with past experiences and knowledge
Translocation: anatomical reorganization
Memory consolidation (MC): memory becomes more stable
Stabilization
Enhancement
Erasure: active removal of memory representations
Both sleep and memory are composed of several different stages/groups as does the development of a memory
Similar to sleep it also develops over time
Acquisition:
initially formed by engaging with an object or performing an action, leading to the formation of a representation of the object or action.
Fragile until first sleep period
Most common MC:
memory consolidation refers to a process whereby a memory becomes increasingly resistant to interference from competing or disrupting factors in the absence of further practice, through the simple passage of time
Stabilization: occurs during wake
Enhancement: primarily if not exclusively duing sleep
restoring previously lost memories
producing additional learning
 Active retention instead of its decay or the enhancement of it over ts simple maintenace

16. Sleep and Declarative MC
Subtleties of task alter results post training REM sleep.
Old supportive
De Koninck: foreign language learning;
% increase in REM Sleep ~ degree of successful learning
Old contradictory
Meienberg: unrelated word pairs;
No evidence of altered post training sleep architecture
Different behavioral measures may be more/less sensative to identifying these consolidation processes
same task diff index of learning diff results
REM sleep plays an active role in memory consolidation and that posttraining increases reflect a homeostatic response to the increased demands for REM-dependent consolidation.
New supportive
Born: Related word pairs;
Improvement in association test and increase in SWS and alterations in sleep characterization

17. Sleep and Declarative MC
Subtleties of task alter results for post training REM sleep.
Old supportive
De Koninck: foreign language learning;
% increase in REM Sleep ~ degree of successful learning
Old contradictory
Meienberg: unrelated word pairs;
No evidence of altered post training sleep architecture
Nature of learning stask is shifted form retaining completely novel assaociations to the strengthening of well formed preexcisting associations for recall at testing
New supportive
Born: Related word pairs;
Improvement in association test and increase in SWS and alterations in sleep characterization

18. Differences in studies
Level of difficulty
Emotional saliency
Index of learning
Episodic learning
Semantic learning
Consideration of effects from lack of sleep
(stress, alertness, attention span)

19. Associative memories Are altered in a state dependent manner
REM- Selective facilitation of accessing weak associations
Enhancement of flexible creative processing of acquired information
Sleep can trigger insight to a problem and thus improve performance strategy

20. Take Home Message
SWS and REM sleep contribute to the consolidation of complex, emotionally salient declarative memories embedded in networks of previously existing associative memories

21. Procedural Memories: Motor Tasks
Retention impaired with loss of Stage 2 NREM sleep
Full night of sleep significantly increases the speed and accuracy
Sleep on first night of training critical for delayed performance improvements
of rotary pursuit task
of tapping task.

22. Procedural Memories: Visual Task
Performance benefits are completely dependent on the first night of sleep after the training period

23. Procedural Memories: Auditory
Regardless of morning or evening training improvements only occurred across a full night of sleep
Sleep deprivation inhibited the normal changes in brain evoked response potentials
Subsequent nights of sleep can restore performance to post training levels
Suggests a process of sleep cxependent copnsolidation capable of reestabliushing previously learned complex auditory skil memory

24. Neuroimaging: Not so Instant Replay

25. E-Physiology Sleep spindles (Stage 2 NREM) Phasic REM and PGO waves
Increase amplitude
Phase locked with theta waves
Induced stimulation at the troughs of theta waves yields to LTD

26. Gene Expression

27. Objections and Contradictions
Importance of considering differences in study protocol
Brief memory test
Affects of Drugs

28. Untouched areas Stabilization Association Translocation
Reconsolidation

29. Bibliography
The American Heritage Illustrated Encyclopedic Dictionary; Houghton Mifflin Company, Boston, 1982.