Sleep and Dreams

Sleep and Dreams Why Sleep is Interesting • Puzzle of Function • Role in Learning, Memory • Insomnia, Other Sleep Disorders • Lapse in Consciousness – Consciousness as Wakefulness – Contrast with “Dreamless Sleep” • Conscious of Dreams? • Unconscious Processing • Mind-Body Problem – Physiological Correlates of Sleep/Dreams 1 Diagnosis of Sleep • Overt Behavior – Relaxation – Prone Posture – Slow, Even Breathing • Subjective Experience – Interruption of Stream of Consciousness – Disorientation upon Awakening – Memory Failure – Dream Recall Polysomnography Rechtschaffen & Kales (1968) The EEG Spectrum Hugdahl (1995) 2 Prominent EEG Bands • EEG Bands – Alpha (8-12 Hz) – Beta (18-30 Hz) – Gamma (30-50 Hz) – High Gamma (>250 Hz) Wikipedia Hugo Gamboa Dez 2005 – Delta (0.5-4 Hz) – Theta (5-7 Hz) The Waking EEG • Alpha Activity – – – – Slow High-Amplitude Rhythmic Arousal • Inverted-U • Beta Activity – – – – Fast Low-Amplitude Desynchronized “Looking” Drowsiness • Eyes Closed • Low Body Motility • Decrease in Body Temperature • EEG Alpha Activity – Initial Increase – Subsequent Decrease 3 Descending Stage 1 • EEG – Alpha Disappears – Desynchronized Activity • EMG Muscle Relaxation • EOG Slow Rolling Eye Movements • Lack of Behavioral Response • Denial of Sleep on Awakening? Stage 2 • EMG Relaxation • EOG SREMs • EEG Changes – Spindles – K-complexes K-Complex Spindle Stage 3 • • • • EMG Relaxation EOG SREMs EEG Delta Activity Awakening to Loud Noise, Name 4 Stage 4 • • • • EMG Relaxation EOG SREMs EEG Delta Activity Awaken Groggy (Sleep Inertia) Stage REM • EEG Resembles Stage 1 • EMG Relaxation – Sleep Paralysis – Narcolepsy • EOG REMs – Conjugate • ANS Arousal – High EKG • Awaken Alert Stage NREM (SWS) Stages of Sleep “Descending” Stage 1 Stages 2, 3, 4 • • • • EMG Relaxed EOG SREMs EEG Slowing “Slow-Wave Sleep” – Stages 3, 4 Stage REM “Ascending” Stage 1 • EMG Relaxed • EOG REMs • EEG Fast 5 Sleep Architecture in Disorders of Consciousness Cologan et al. (2009) Coma • EEG Slowing Vegetative State • Sleep Stages – Delta, Theta – Spindles, K-complexes – Alternating REM, SWS • “Spindle Coma – Better Prognosis? Nervous System Activity in Sleep SWS REM Slow Decline Slow Decline Maintained Decreased Reduced Variable Variable Impaired Increased High Slow Decline Normal Reduced Infrequent, Slow Eliminated Suppressed Increased Rapid, Conjugate Autonomic Heart Rate Respiration Thermoregulation Brain Temperature Cerebral Blood Flow Somatic Postural Tension Patellar Reflex Phasic Twitches Eye Movements Hobson (1995) 6 Succession of Sleep Stages Dement (1976) 19 Consciousness During Sleep • Aspects of Information-Processing – Pickup Information from Environment – Integrate with Pre-Existing Knowledge – Respond Meaningfully while Asleep – Remember in Morning • Evidence (Largely Anecdotal) – Body Movements – Awakening to Meaningful Sounds – Awakening at Preselected Times – Dream-Incorporation Sleep Stage and Reports of Sleeping % of Subjects Webb (1975) 100 90 80 70 60 50 40 30 20 10 0 Don't Know Awake Asleep Awake 1 2 3, 4 Sleep Stage 7 Falling Asleep Wyatt et al. (1994) • Paired Associates (hot-cold) – Lights out, 1/minute – Repeat word pair • Repetition failure – 15 secs of alpha-free Stage 1 – further 30 secs or 10 min • Awakening – Recall and Recognition Tests – 10 Cycles Retrograde Amnesia in Sleep Wyatt et al. (1994) Explicit vs. Implicit Memory • Explicit Test – Associate-Cued Recall • Implicit Test – Free Association 8 Explicit vs. Implicit Memory: Last 2 Minutes Before Sleep Corrected % Targets Wyatt et al. (1994) 90 80 70 60 50 40 30 20 10 0 30sW Baseline 10mW 30sS 10mS Explicit Implicit Memory Test Dreaming and REM Sleep Aserinsky & Kleitman (1953) • Observed Cyclical Shift from SREM to REM – 10-20 Minute Bursts – c. Every 90 Minutes • Awaken Subjects in Various Sleep Stages • “Were You Dreaming?” – Awakened in REM, 74% – Awakened in NREM, 17% • Sleep Not a “Passive” Phenomenon – 2 Kinds of Sleep Sleep Stage and Dream Recall Dement (1976) % Dream Reports 100 80 60 REM 40 NREM 20 0 A&K (1953) 9 Studies Study 9 Mental and Behavioral Activity During Sleep • Descending Stage 1 – Hypnagogic Reverie • Stage NREM – Reverie, Thoughts, Images – Sleepwalking, Sleep Talking, Night Terrors • Stage REM – Dreams, Nightmares • Ascending Stage 1 – Hypnopompic Reverie Hypnagogic Reverie Schacter (1976) • Imagery in Descending Stage 1 – Visual • Patterns, Static Objects, Complex Scenes – Auditory • Images, Music, Own Name • “Myoclonic Jerk” – Accompanying imagery – Muscles-Tendons Antagonism • Hypnopompic Reverie (Ascending Stage 1) – Sleep Paralysis Night Terrors (Pavor Nocturnus, Incubus) Gastaut & Broughton (1964) • Behavioral – Inarticulate Scream, Cry for Help, Fear – Unable to account for distress – Return to (peaceful) sleep – No memory upon awakening • Physiological – Intense ANS Discharge – Arousal from Early Stages 3, 4 • Not nightmare 10 Nightmares Hartmann (1984) • Frightening Dream – Awakens Sleeper • Stage REM – Late in Night Fuseli, the Nightmare (1781) Nightmares and Night Terrors Hartmann (1984) Sleepwalking (Somnambulism) Kales et al. (1966) • • • • • • Stage NREM (SWS) Random, Purposelessness Dexterity Episodic Affect Development – Children – Adults 11 Sleeptalking (Somniloquy) Arkin et al. (1978) • Speech, Other Meaningful Sounds – No Awareness on Awakening • Children vs. Adults • REM, Concordant with Dream Contents – Syntax, Semantics – Monologue, One-Sided Conversation • NREM, Discordant with Dream Contents – Aphasic? Parasomnias In REM • REM Sleep Behavior Disorder • Recurrent Isolated Sleep Paralysis • • • • In NREM Sleepwalking Night Terrors Bruxism Restless Leg Syndrome Early Studies of Sleep-Learning • Thorndike (1916), Morse Code – Learning – Fatigue – Surreptitious Practice • Fox & Robins (1952) – Chinese-English Paired-Associates • Correct Pairs, Incorrect Pairs • Music as Control – Savings in Relearning 12 Sleep and Waking Learning Fox & Robins (1952) Trials to Learn in AM 12 10 8 6 4 2 0 Correct Music Incorrect Pair Type Analysis of Sleep Learning 100 90 80 70 60 50 40 30 20 10 0 Hear Recall Recog Sleep Stage Alpha Activity in Memory Simon & Emmons (1956) 35 30 % of Items % of Items Simon & Emmons (1955) 25 20 15 10 5 0 10Sec None No Hear Alpha Activity Following Item 13 “Sleep learning is possible, to the extent that the subject remains awake” Simon & Emmons (1955) Explicit and Implicit Memory for Sleep Learning Wood et al. (1992) • Night 1, Homophone Pairs – War-Peace, Tortoise-Hare – Homophone Spelling • Night 2, Category-Instance Pairs – Metal-Gold, Animal-Horse – Category Instance Generation • Signs of Arousal – Body Movement – EEG Alpha, SREMs Homophone Priming Standardized Scores Wood et al. (1992) 80 70 60 50 40 30 20 10 0 Targets Lures Sleeping Waking Condition 14 Category-Instance Priming Wood et al. (1992) Standardized Scores 120 100 80 Targets 60 Lures 40 20 0 Sleeping Waking Condition “Sleep learning is possible, to the extent that the subject remains awake” Simon & Emmons (1955) Memory for Dreams • Problem – High Frequency of Dreams in Stage REM – 4-5 Epochs of REM in Night’s Sleep – Why Remember Only 1 Dream (At Most)? • Dream Occurs in Primary/Working Memory – REM Awakening Permits Immediate Readout – Consolidation – Retrieval 15 Factors Affecting “Consolidation” • Low Arousal During Sleep • REM Awakenings – Abrupt vs. Gradual Arousal – Distraction • Salience Sleep Stage and Dream Recall Aserinsky & Kleitman (1953); Dement (1976) % Dream Reports 100 80 60 REM 40 NREM 20 0 A&K (1953) 9 Studies Study Sleep Stage and Mentation Foulkes (1962); Foulkes & Schmidt (1983) % of Awakenings 100 80 60 REM 40 NREM 20 0 1962 1983 Study 16 Normative Characteristics of Dreams Snyder (1970) • • • • • • • • Vivid, Complex Imagery Temporal Progression Primarily Visual Familiar Setting Dreamer as Central Character Moderate to High Credibility Fairly Coherent Flat Affect – Nightmares Characteristics of NREM Mentation • Stage 1 (NREM) – Reverie, Daydreaming • Stage 2 – Imageless Thoughts, Reverie • Stage 3 – Imageless Thoughts, Floating Images • Stage 4 – Incoherent Reports (Sleep Inertia?) Analysis of Sleep Mentation Foulkes & Schmitt (1983) Quality REM NREM Mental Content % "Dreams" 93% 67% 80% 40% Dreams 74% 27% Length 5.5 1.3 17 Dream Content Hall & Van de Castle (1966) • Dreams Constant Despite Cultural Change • No Changes in Content Across Adulthood • Stable Patterns of Differences Across Cultures – Characters: Women, M=F; Men, M>>F – Aggression>Friendliness – Misfortune>Good Fortune – Emotion: Negative>Positive • Individual Differences Consistent with Waking Personality The Interpretation of Dreams Freud (1900) “I shall demonstrate that there is a psychological technique which makes it possible to interpret dreams, and that on the application of this technique, every dream will reveal itself as a psychological structure, full of significance….” Dreams as Wish Fulfillments Freud (1900) • The Dream of Irma – Injection of Trimethylamine • Anna’s Dream (a Paraphrase) – Stwabewwies! 18 Vocabulary of the Dream Theory Freud (1900) • Day Residues • Manifest vs. Latent Content • Dreamwork – Displacement – Condensation – Visual Representation – Secondary Revision Common Dream Symbols Freud (1900), Chapter 6 • A Hat as a Symbol of a Man (or of Male Genitals) • A “Little One” as the Genital Organ – “A Little One Being Run Over” as a Symbol of Sexual Intercourse • • • • • The Genitals Represented by Buildings, Stairs and Shafts The Male Organ Represented by Persons The Female Organ by a Landscape Dreams of Castration in Children Urinary Symbolism Topographical Theory of the Mind Freud (1900)’s “Compound Instrument” • • • • • Perceptual, Mnemic Systems Motor Activity Systems Ucs, Pcs, Cs Cathexis and Anticathexis Replaced by Functional Theory (1923) – Id, Ego, Superego 19 Dreaming Begins with “PGO Waves” Brooks & Bizzi (1963), after Jouvet, Michel, & Courjon (1959) • Implanted Microelectrodes – Cats, Rodents • Activity During REM Sleep – Not during SWS, Waking • Sequential Activation 1. Pons 2. Lateral Geniculate Nucleus Types of Neuron Executive 3. Occipital Cortex Trigger, Transfer Modulatory Aminergic (NE, 5-HT) Cholinergic (Ach) Activation-Synthesis Theory of Dreams Hobson & McCarley (1977) • Cyclic Activation of Cortex – Controlled by Biological Clock – Consequences of Activation • • • • Feedback of Eye Movements Motor Commands Vestibular Activity ANS Activity • Automatic Synthesis of Imagery – Corresponding to Sensory Activity • Dreams are Essentially Meaningless AIM Model of Consciousness “An Integrative Theory of Mind-Brain States” Hobson et al. (1990, 1992, 1995, 1999, 2000, 2001, 2014) Psychological Level • Alertness Physiological Level • Cortical Activation – RAS – Neural Firing Rate in Brainstem • Input Source – Internal vs. External • Information Processing – Attentiveness • Sensory/Motor Channels – Input-Output Gating • Neuromodulatory Balance – Aminergic Neurons • Norepinephrine (NE) • Serotonin (5-HT) – Cholinergic Neurons • Acetylcholine (Ach) 20 Brainstem Neuromodulatory Systems Hobson (2001) • • • • Acetylcholine Noradrenergic Serotonergic (Dopaminergic) – – Not Visible Not Yet in AIM Model Noradrenergic Neuromodulatory System Hobson (2001) • Locus Coeruleus – – – – – – – Spinal Cord Brainstem Cerebellum Thalamus Subthalamus Limbic System Neocortex Seratonergic Neuromodulatory System Hobson (2001) • Raphe Nuclei – – – – – – – Spinal Cord Brainstem Cerebellum Thalamus Subthalamus Limbic System Neocortex 21 Acetylcholine Neuromodulatory System Hobson (2001) • Sources – Pons • • • • Thalamus Subthalamus Basal Forebrain Limbic System – Basal Forebrain • Neocortex • Limbic System Dopaminergic Neuromodulatory System Hobson (2001) • Midbrain – Limbic System – Neocortex – Extrapyramidal Motor System • Not Involved in Sleep and Dreams • Relevant to Psychedelic States – LSD The AIM State-Space Hobson (1990) Low Activation High High Aminergic Modulation External High Cholinergic Input Source Internal 22 Waking Consciousness in the AIM State-Space Activation Low High Waking High Aminergic Modulation External Input Source High Cholinergic Internal NREM in the AIM State-Space Activation Low High Waking High Aminergic NREM Modulation External Input Source High Cholinergic Internal REM in the AIM State-Space Activation Low High Waking High Aminergic NREM Modulation External REM High Cholinergic Input Source Internal 23 Sleep Cycle in the AIM State-Space Activation Low High Waking High Aminergic NREM Modulation External REM Input Source High Cholinergic Internal AIM and Sleep Hobson (1990) • Waking – High Activation, External Information – Aminergic > Cholinergic • NREM Sleep – Low Activation, Internal Information – Aminergic = Cholinergic • REM Sleep – High Activation, Internal Information – Cholinergic > Aminergic Consequences of REM Modulation • High Levels of Cortical Activation – Lots of Mental Activity • Shift from External to Internal Inputs – Mental Activity Dominated by Memory – No Behavioral Outputs • Low Aminergic Activity – Poor Memory on Waking 24 The AIM Model Beyond Sleep and Dreams Hobson et al. (2000) • Activation – Normal Consciousness (High) – Quiet Waking (Low) • Input – Daydreams, Fantasies • Modulation – Psychedelic Drugs – Depression Implications of AIM Model • Brainstem Critical for Dreams – Reticular Activating System • Dreams Meaningless – Contents a Product of Random Activation • Focus on Formal Properties of Thought – Similar to Waking Thought But Are Dreams Really Devoid of Meaning? Brain Damage and Dreaming Solms (1997) • 200/332 Patients with No Changes – Dosolateral Prefrontal Cortex – Sensorimotor Cortex – Primary Visual Cortex • 121/132 Patients Lost All Dreaming – Parietal Lobes (Spatial Representation) – Frontal-Limbic Region (Executive Functions) • 2 Patients Lost Visual Imagery – Damage in Visual Association Cortex 25 Are Dreams and REM Dissociable? Solms (2000) • Dreams Occur in NREM as well as REM – 5-10% of NREM Awakenings Dream Report • Indistinguishable from REM Dream Reports – 5-30% of REM Awakenings No Dream • Forebrain Mechanisms Critical for Dreaming – Cholinergic Systems Control REM – Frontal/Dopaminergic Systems Control Dreaming • A Double Dissociation? – Pontine Damage Suppresses REM, not Dreams – Frontal Damage Suppresses Dreams, not REM A New Dream Theory Solms (2000) • Evidence for a Dopaminergic Hypothesis – Forebrain Transection Eliminates Dreaming • Interrupts Mesocortical/Mesolimbic Dopamine System • No Effect on REM Sleep – L-dopa Stimulates Vivid Dreams, Nightmares – Haldol Inhibits Frequent/Vivid Dreams • Dream-Generation Process – Cerebral Activation During Sleep • Many Different Origins, Not Just Pontine Activity A “Dream-On” Mechanism? Solms (2000) • Mesocortical/Mesolimbic Dopamine System – Vental Tegmental Area (VTA) – Amygdala – Prefrontal Cortex • Dreams as Wish-Fulfillments? – Goal-Directed Behavior • A “Seeking System” – Reward/Pleasure thebrain.mcgill.ca • Neuro-Psychoanalysis 26 Hobson and Solms Compared and Contrasted Domhoff (2005) • Differences – Role of PGO Waves – Association of Dreaming with REM – Role of Neurotransmitters • Cholinergic/Adrenergic vs. Dopamine • Similarities – Dreaming as Psychosis – Dream Content Insignificant – Need to Polarize Debate A Cognitive Theory of Dreams Foulkes (1985) • Development of Dreaming – Dream Recall Minimal Before Age 9 – Low Levels of Negative Content in Children • Dreaming Instigation – Random Activation of Memory Structures • Episodic, Semantic • Dream-Production system – Organizes Random Elements • Coherent Dream Experience Sources of Mnemonic Activation in Sleep Foulkes (1985) • External or Internal Stimuli – Spontaneous Brain Activity • Associations with Activated Memories – Looser in Sleep • Voluntary Retrieval – Absent 27 Dream-Production System Foulkes (1985) • Dreaming as Thinking – Visual-Spatial Thinking Skills • Right Hemisphere? – Syntactical Rules, Script Knowledge • Left Hemisphere? • One Dream-Production at All Stages – Cortical Excitation Greater in REM • Developmental Trends (“Piagetian”) – No Dreams During Sensory-Motor Period • Amnesia as Encoding Failure The Meaning of Dreams Foulkes (1985) • Indicative Meaning – Reflect Mind of Dreamer • Random Sampling • Personality • Life Situation Dream Content Revisited Domhoff (2001, 2005) • Uncertain Relationship b/ Dreams, Physiology – REM and Dreaming (REM Deprivation) – Unusual Eye Movements and Bizarreness • Faithfulness to Everyday Waking Life – Commonplace, Familiar Settings – Low Degree of Drama – Low Degree of Bizarrenes – Little Emotion – Thinking Generally Coherent • Laboratory vs. Home Environments 28 Neurocognitive Theory of Dreams Domhoff (2001, 2005) • Neural Network for Dreaming – Forebrain • Limbic System • Inferior Parietal Cortex • Dreaming as Cognitive Achievement – Develops Over First 9 Years of Life • Dreams Continuous with Waking Life – Continuity Principle – Repetition Principle 29