Sleep, Learning, and Sleep, Learning, and Dreams: Off-Line Dreams: Off-Line

Memory ReprocessingMemory ReprocessingStickgold, Hobson, Fosse, FosseStickgold, Hobson, Fosse, Fosse

Group #1 Group #1

D. Doan, B. Gee, E. Lee, J. D. Doan, B. Gee, E. Lee, J. TranTran

February 13, 2008February 13, 2008

IntroductionIntroduction

Association between sleep, learning, Association between sleep, learning, and memoryand memory

Behavioral studiesBehavioral studies Physiology of sleepPhysiology of sleep Cognitive processing in REM and Cognitive processing in REM and

NREMNREM Dreams and memoryDreams and memory Theories of dreamsTheories of dreams

Behavioral Studies of Behavioral Studies of Learning and Memory in Learning and Memory in

SleepSleep REM sleep plays a role REM sleep plays a role

in:in: LearningLearning Procedural memoryProcedural memory Emotional memoriesEmotional memories Modifying Modifying

neocortical networksneocortical networks

Behavioral Studies of Behavioral Studies of Learning and Memory in Learning and Memory in

SleepSleep Animal studiesAnimal studies

Smith (1985)Smith (1985)““REM windows”REM windows”

Occurred after procedural Occurred after procedural trainingtraining

REM sleep increasesREM sleep increasesREM deprivation leads to REM deprivation leads to diminished retentiondiminished retention

Deprivation-induced stressDeprivation-induced stress

Behavioral Studies of Behavioral Studies of Learning and Memory in Learning and Memory in

SleepSleep Human studiesHuman studies

Posttraining REM deprivation Posttraining REM deprivation impairs procedural learningimpairs procedural learning

Enhanced recall for emotional Enhanced recall for emotional memories after REM sleepmemories after REM sleepe.g. major depression and PTSDe.g. major depression and PTSD

Behavioral Studies of Behavioral Studies of Learning and Memory in Learning and Memory in

SleepSleep Visual texture discrimination taskVisual texture discrimination task

Behavioral Studies of Behavioral Studies of Learning and Memory in Learning and Memory in

SleepSleep Visual texture discrimination taskVisual texture discrimination task

Behavioral Studies of Behavioral Studies of Learning and Memory in Learning and Memory in

SleepSleep REM and Modification of Neocortical REM and Modification of Neocortical

NetworksNetworks Not just procedural learning Not just procedural learning

Complex logic gamesComplex logic gamesForeign language acquisitionForeign language acquisitionIntensive studyingIntensive studying

Sleep Architecture and Sleep Architecture and PhysiologyPhysiology

Synchronous brain activitySynchronous brain activity SWS sleep SWS sleep

Cortical long-term potentiation Cortical long-term potentiation (LTP)(LTP)

Sharp wave potentialsSharp wave potentials REM sleepREM sleep

Hippocampal LTPHippocampal LTP Hippocampo-neocortical dialogHippocampo-neocortical dialog

Sleep Architecture and Sleep Architecture and PhysiologyPhysiology

Synchronous brain activity cont.Synchronous brain activity cont. Ponto-geniculo-occipital (PGO) Ponto-geniculo-occipital (PGO)

waveswavesVisual cortexVisual cortexMotor cortexMotor cortexAmygdalaAmygdalaHippocampusHippocampusTransition from NREM to REMTransition from NREM to REM

Gamma wavesGamma wavesBinding problemBinding problem

Sleep Architecture and Sleep Architecture and PhysiologyPhysiology

Neuronal ReplayNeuronal Replay SWSSWS

Neuronal replay occurs after half Neuronal replay occurs after half an houran hour

REMREMNeuronal replay occurs after 24 Neuronal replay occurs after 24 hourshours

ImplicationsImplications

Sleep Architecture and Sleep Architecture and PhysiologyPhysiology

NeuromodulatorsNeuromodulators Noradrenergic (NE) locus Noradrenergic (NE) locus

coeruleuscoeruleus Serotonergic (5-HT) dorsal Raphe Serotonergic (5-HT) dorsal Raphe

nucleusnucleus Cholinergic (Ach) nuclei of Cholinergic (Ach) nuclei of

dorsolateral ponsdorsolateral pons

Sleep Architecture and Sleep Architecture and PhysiologyPhysiology

Regional Brain ActivationRegional Brain Activation PET studiesPET studies SWSSWS

All brain regions less active than wakingAll brain regions less active than waking REMREM

Dorsolateral prefrontal cortex (DLPFC) Dorsolateral prefrontal cortex (DLPFC) ↓↓

Anterior cingulate and medial Anterior cingulate and medial orbitofrontal cortices ↑orbitofrontal cortices ↑

Amygdala ↑Amygdala ↑

Sleep Architecture and Sleep Architecture and PhysiologyPhysiology

Plasticity and LearningPlasticity and Learning Pontine reticular formation (PRF) Pontine reticular formation (PRF)

activation and PGO wavesactivation and PGO wavesConsolidate learning and form new Consolidate learning and form new associationsassociations

Protein synthesis and phosphokinase Protein synthesis and phosphokinase A (PKA)A (PKA)Hippocampal learningHippocampal learning

Sleep Architecture and Sleep Architecture and PhysiologyPhysiology

Plasticity and LearningPlasticity and LearningVisual deprivation cat studiesVisual deprivation cat studies

Cognitive Processing in Cognitive Processing in REM and NREMREM and NREM

Approaches to studies of dreamingApproaches to studies of dreaming Identifying isomorphisms betweenIdentifying isomorphisms between

Neurophysiological features of Neurophysiological features of REMREM

Formal properties of REM Formal properties of REM dreamsdreams

Measuring cognitive processesMeasuring cognitive processes

Cognitive Processing in Cognitive Processing in REM and NREMREM and NREM

Measuring cognitive processesMeasuring cognitive processes Semantic priming favors weaker Semantic priming favors weaker

associations after REM associations after REM awakenings than after NREM awakenings than after NREM awakeningsawakenings

Solving anagrams is similarly Solving anagrams is similarly enhanced after REM compared enhanced after REM compared with NREM awakeningswith NREM awakenings

Cognitive Processing in Cognitive Processing in REM and NREMREM and NREM

Semantic priming across wake-sleep Semantic priming across wake-sleep statesstates

Cognitive Processing in Cognitive Processing in REM and NREMREM and NREM

REM favors more fluid thinking than REM favors more fluid thinking than NREMNREM

Cognitive Processing in Cognitive Processing in REM and NREMREM and NREM

Physiological characteristics of REMPhysiological characteristics of REM Shift in neuromodulatory balanceShift in neuromodulatory balance ↓ ↓ activity in DLPFC & ↑ activity in activity in DLPFC & ↑ activity in

anterior cingulate cortex and anterior cingulate cortex and amygdalaamygdala

Decreased outflow of information Decreased outflow of information from hippocampus to neocortexfrom hippocampus to neocortex

Cognitive Processing in Cognitive Processing in REM and NREMREM and NREM

The brain in REM is tuned more for The brain in REM is tuned more for the processing of associative the processing of associative memories than for the simple memories than for the simple consolidation of recent memory consolidation of recent memory tracestraces

Dreams and MemoryDreams and Memory

Verbal reportsVerbal reports More hallucinations and less More hallucinations and less

directed thinkingdirected thinking Memory sourcesMemory sources

Episodic memoryEpisodic memory

Dreams and MemoryDreams and Memory

Emotions and Emotions and dreamingdreaming PhysiologyPhysiology

Sleep onset Sleep onset dreamingdreaming Video game Video game

studiesstudies

Dream TheoriesDream Theories

Important QuestionsImportant Questions How dreams are constructedHow dreams are constructed What is the purpose of the What is the purpose of the

constructionconstruction Non-uniform statesNon-uniform states Unique REM physiologyUnique REM physiology

Weak neo-cortical associationsWeak neo-cortical associations

Dream TheoriesDream Theories

Role of dreamingRole of dreaming Evaluating neocortical associationEvaluating neocortical association Strengthening or weakening Strengthening or weakening

associationsassociations

Thank you!Thank you!