1 / 29

Sleep and Memory: Overview

Sleep and Memory: Overview. Rachel Miriani Neural Systems Nov 29, 2004. Introduction to Memory. Memory. “The mental faculty of retaining and recalling past experiences; the ability to remember.” 1. Introduction to Memory. Memory. Declarative. Non-Declarative.

bell-roberson
Download Presentation

Sleep and Memory: Overview

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. Introduction to Memory Memory “The mental faculty of retaining and recalling past experiences; the ability to remember.”1

  3. Introduction to Memory Memory Declarative Non-Declarative “Consciously accessible memories of fact-based information”- The What. Non-conscious

  4. Introduction to Memory Memory Declarative Non-Declarative What. Non-conscious Semantic Episodic Not event specific general knowledge Experiences and events from ones past.

  5. Introduction to Memory Memory Declarative Non-Declarative What. Non-conscious Episodic Semantic Procedural Skills Conditioning Non-associative Priming

  6. Introduction to Memory Memory Declarative Non-Declarative What. Non-conscious Episodic Semantic Procedural Skills Conditioning Non-associative Priming

  7. Introduction to Sleep: REM Sleep REM NREM • REM: Rapid Eye Movement • Muscle tone decreases. • EEG oscillations are desynchronized • Gamma waves appear- 30-80Hz 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 1 2 3 4

  8. Introduction to Sleep Sleep REM NREM 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 1 2 3 4 *Increasing depth of sleep *EEG frequency slows down

  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

  10. 1 Cycle of REM and NREM takes ~90mins • Ratio of REM to NREM changes with each cycle

  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 • Symmetrical distribution and most apparent in the frontal lobe. • Rapid, irregular, and low voltage • Alpha waves: 7.5-13Hz • 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: 3.5-7.5Hz • 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

  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

  15. Subtleties of task alter results post training REM sleep. Sleep and Declarative MC • 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 • New supportive Born: Related word pairs; Improvement in association test and increase in SWS and alterations in sleep characterization

  16. 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 • New supportive Born: Related word pairs; Improvement in association test and increase in SWS and alterations in sleep characterization

  17. Differences in studies • Level of difficulty • Emotional saliency • Index of learning • Episodic learning • Semantic learning • Consideration of effects from lack of sleep

  18. 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

  19. 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

  20. 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

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

  22. 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

  23. Neuroimaging: Not so Instant Replay

  24. 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

  25. Gene Expression

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

  27. Untouched areas • Stabilization • Association • Translocation • Reconsolidation

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

More Related