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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.

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sleep and memory overview

Sleep and Memory: Overview

Rachel Miriani

Neural Systems

Nov 29, 2004

introduction to memory
Introduction to Memory

Memory

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

slide3

Introduction to Memory

Memory

Declarative

Non-Declarative

“Consciously accessible memories of fact-based information”- The What.

Non-conscious

slide4

Introduction to Memory

Memory

Declarative

Non-Declarative

What.

Non-conscious

Semantic

Episodic

Not event specific general knowledge

Experiences and events from ones past.

slide5

Introduction to Memory

Memory

Declarative

Non-Declarative

What.

Non-conscious

Episodic

Semantic

Procedural Skills

Conditioning

Non-associative

Priming

slide6

Introduction to Memory

Memory

Declarative

Non-Declarative

What.

Non-conscious

Episodic

Semantic

Procedural Skills

Conditioning

Non-associative

Priming

slide7

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

introduction to sleep
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

slide9

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

slide10
1 Cycle of REM and NREM takes ~90mins
  • Ratio of REM to NREM changes with each cycle
slide11

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
slide12

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
neurochemistry
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
developing a memory
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
sleep and declarative mc
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

slide17

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

differences in studies
Differences in studies
  • Level of difficulty
  • Emotional saliency
  • Index of learning
  • Episodic learning
  • Semantic learning
  • Consideration of effects from lack of sleep
associative memories
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
take home message
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
procedural memories motor tasks
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
procedural memories visual task
Procedural Memories: Visual Task
  • Performance benefits are completely dependent on the first night of sleep after the training period
procedural memories auditory
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
e physiology
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
objections and contradictions
Objections and Contradictions
  • Importance of considering differences in study protocol
    • Brief memory test
  • Affects of Drugs
slide28
Untouched areas
    • Stabilization
    • Association
    • Translocation
    • Reconsolidation
bibliography
Bibliography
  • The American Heritage Illustrated Encyclopedic Dictionary; Houghton Mifflin Company, Boston, 1982.