Ch. 5 Consciousness and Sleep PDF

CONSCIOUSNESS  What is Consciousness? Consciousness: a person’s subjective awareness, including thoughts, perceptions, experiences of the world, and self- awareness § Is it all just an illusion? § Are there neural correlates of consciousness? § Are certain structures i...

CONSCIOUSNESS  What is Consciousness? Consciousness: a person’s subjective awareness, including thoughts, perceptions, experiences of the world, and self- awareness § Is it all just an illusion? § Are there neural correlates of consciousness? § Are certain structures important or is consciousness an emergent property of the brain operating in its entirety? The ‘Hard Problem of Consciousness’: the problem in explaining why we have subjective experiences  SLEEP: A PREDICTABLE SCHEDULE Staying on Schedule Circadian rhythms: biological rhythms with a ~24 hour periodicity 1. Entrainment: synchronization between biological rhythms and external cues (zeitgebers) Light Entrainment 1. Slowly changing levels of background illumination detected by specialized ganglion cells of the retina 2. Light signals communicated to brain via the optic nerve to the optic chiasm 3. Suprachiasmatic nucleus (SCN) situated above optic chiasm receives light information 4. SCN innervates pineal gland to stimulate release of melatonin 5. Melatonin accumulates with darkness and onset of sleep Staying on Schedule 2. Endogenous rhythms: ‘free running’ biological rhythms generated by our body that are independent of zeitgebers § Genetic feedback loops  Why Do We Sleep? Restore and repair hypothesis: sleep restores energy levels and allows for repairs on the body from the day’s activities Physiological ‘housekeeping’ Preserve and protect hypothesis: sleep preserves energy and protects the individual organism from harm Sleep differences between predator and prey species SLEEP STAGES  The Stages of Sleep Beta waves: awake Alpha waves: drowsy state; loss of attention Stage 1: Breathing, heart rate, blood pressure decrease Stage 2: Become less responsive to external stimuli; sporadic brain activity Stage 3-4: Brain activity slows; difficult to wake Sleep Cycles and REM REM sleep: stage of sleep characterized by quickening brain waves, deep relaxation, inhibited body movement, and rapid eye movements (REM) Paradoxical sleep and REM rebound  Sleep over the lifespan There is no ‘magic number’ for sleep Amount of sleep needed varies between individuals according to age and genetics Sleep is developmentally important Sleep and Learning REM facilitates learning, especially for complex tasks § Late REM phases especially important for ‘locking in’ learning Sleep and Learning Slow-wave sleep (i.e., stages 3 and 4) particularly important for the learning of autobiographical memories § Neural replay: Fast-forward playback in which pattern of neural activity that occurred while awake is repeated during sleep  SLEEP DEPRIVATION  Sleep Deprivation Characteristics of sleep deprivation: § More readily falls asleep § Irritability/emotional deficits § Attention/vigilance deficits § Normal energy as long as one is occupied; malaise sets in upon sitting down or resting § Reading/studying next to impossible § After 2-3 days microsleeps begin to occur The Costs of Sleep Deprivation Cognitive and emotional deficits Increased risk of vehicular accidents Increased number of preventable medical errors Sleep Displacement Sleep displacement: when an individual is prevented from sleeping at the normal time § Jet lag § Daylight savings time  Sleep Hygiene Practicing good sleep hygiene trains your brain and body to sleep more readily DREAMING The Psychoanalytical Approach Sigmund Freud: Published The Interpretation of Dreams (1900) § Argued dreams are unconscious expressions of wish fulfillment Manifest content: the images and storylines that we dream about Latent content: the actual symbolic meaning of a dream built on suppressed sexual or aggressive urges Modern Theories of Dreaming Activation–synthesis hypothesis: suggests that dreams arise from brain activity originating from bursts of excitatory messages arising from the brainstem Modern Theories of Dreaming Problem-solving theory: thoughts and concerns are continuous from waking to sleeping, and that dreams may function to facilitate finding solutions to problems encountered while awake Memorability of Dreams Waking up and stress hormones: norepinephrine and cortisol DISORDERS OF SLEEP  Insomnia Onset insomnia: difficulty falling asleep Maintenance insomnia: difficulty returning to sleep Terminal insomnia: waking too early Can be further classified as: § Primary insomnia: due to internal source (e.g., worrying) § Secondary insomnias: result of other disorders  Nightmares and Night Terrors Nightmares: particularly vivid and disturbing dreams that occur during REM sleep § Occur during REM sleep Night terrors: intense bouts of panic and arousal that awaken the individual, typically in a heightened emotional state § Occur during NREM sleep  Movement Disturbances Restless legs syndrome: persistent discomfort in the legs and the urge to continuously shift them into different positions REM behaviour disorder: act out dreams due to failure to inhibit motor signals Somnambulism (sleepwalking): a disorder that involves wandering and performing other activities while asleep Sleep Apnea Sleep apnea: temporary inability to breathe during sleep as airway becomes obstructed § Obesity § Damage to medulla Narcolepsy Narcolepsy: extreme daytime sleepiness and even sleep attacks § Few seconds to few minutes § Immediately into REM sleep HYPNOSIS  Hypnosis Hypnosis: a procedure of inducing a heightened state of suggestibility Not a distinct state of consciousness Hypnotic suggestions § Ideomotor: actions to be performed § Challenge: actions not to be performed § Cognitive-perceptual: prompt remembering/forgetting or altered perceptions Theories of Hypnosis Dissociation theory: explains hypnosis as a unique state in which consciousness is divided § Driving on “autopilot” Social-cognitive theory: emphasizes the degree to which beliefs and expectations contribute to increased suggestibility § Conform to expectations Applications of Hypnosis Effective addition to treatment § Medical treatments § Acute pain relief Hypnosis originally used to recover memories § Leads to recovery of false memories § Cannot be used as evidence in courts MIND-WANDERING  Losing Track of Our Thoughts Mind-wandering: an unintentional redirection of attention from the current task to an unrelated train of thought The Idle Mind Never Rests Default Mode Network: a pattern of brain activity associated with self-reflection, introspection, autobiographical memories, and future thinking Abnormal DMN activity linked with certain psychological disorders  DISORDERS OF CONSCIOUSNESS Disorders of Consciousness Consciousness can be assessed on a spectrum of wakefulness/awareness § Glasgow coma scale  Disorders of Consciousness Brain death: condition in which the brain stem no longer functions § No potential for recovery Coma: complete loss of consciousness § Body is still aside from minor twitches § No pupillary response  PERSISTENT VEGETATIVE STATES  Disorders of Consciousness Persistent vegetative state (PVS): a state of minimal to no consciousness § Eyes open but do not track movement § Normal sleep cycles § Best hope for recovery before 6 months § The case of Terry Shiavo  Consciousness in the Unconscious Some PVS patients show signs of consciousness fMRI suggests comprehension of commands and mental imagery Misdiagnosis of vegetative state? Language = consciousness?  APPROACHING NORMAL CONSCIOUSNESS  Disorders of Consciousness Minimally conscious state: marked by the ability to show some behaviours that suggest partial consciousness, even if on an inconsistent basis § Behaviours beyond reflexes Locked-in syndrome: patient is aware and awake but, because of an inability to move, appears unconscious § Cognitive and emotional processing intact Disorders of Consciousness Diminished brain activity as conscious awareness decreases ‘The problem of other minds’ SHORT-TERM DRUG EFFECTS  Short-Term Drug Effects Drugs affect neurotransmitter activity through various agonistic and antagonistic effects Dopamine and Reward Nucleus accumbens: A prime area of activation when a person engages in rewarding behavior LONG-TERM DRUG EFFECTS  Long-Term Drug Effects Tolerance: when repeated use of a drug results in a need for a higher dose to get the intended effect § Metabolic and cellular tolerance § Down regulation of receptors  Down Regulation Pre-synaptic neuron Post-synaptic neuron Long-Term Drug Effects Physical dependence: the need to take a drug to ward off unpleasant physical withdrawal Psychological dependence: the need to take a drug to ward off negative emotions No physical symptoms Top-Down Influences Experience with a drug changes response E.g., marijuana Context-dependent overdoses Anticipatory drug response Anticipatory Drug use response Heart Rate DRUG CLASSES: STIMULANTS Commonly Abused Drugs Stimulants: drugs that speed up the nervous system, typically enhancing wakefulness and alertness § Euphoria, increased energy, lowered inhibitions § Increased dopamine, serotonin, norepinephrine § Tolerance develops quickly § High risk of dependence § E.g., cocaine, amphetamines, ecstasy Commonly Abused Drugs Physical deterioration Cognitive deterioration Hygiene neglected Structural abnormalities in Drug cocktail often cells of the frontal lobes includes ingredients such Users develop difficulties as hydrochloric acid and ignoring irrelevant thoughts farm fertilizer § Stroop test  DRUG CLASSES: HALLUCINOGENS Commonly Abused Drugs Hallucinogens: produce perceptual distortions § Experiences range from euphoria to fear, panic, paranoia § Increased serotonin, blocks glutamate receptors § Tolerance develops slowly § Low risk of dependence § E.g., LSD, ketamine, DMT, psilocybin, salvia divinorum DRUG CLASSES: OPIATES Commonly Abused Drugs Opiates (narcotics): reduce pain and induce extremely intense feelings of euphoria § Intense euphoria, pain relief § Stimulate endorphin receptors § Tolerance develops very quickly § Very high risk of dependence § E.g., morphine, heroin, fentanyl, oxycodone, oxycontin, codeine, opium  Naloxone: Treating Overdoses Endorphins are endogenous pain-relieving neurotransmitters in the brain Drugs that promote endorphin release (i.e., opioids) act as powerful pain relievers Naloxone: drug that blocks endorphin receptor sites to negate the effects of opioids  The Opioid and Fentanyl Crisis Other opioids often laced with highly potent fentanyl Methadone treatment Ongoing class-action lawsuits against opioid manufacturers DRUG CLASSES: SEDATIVES Commonly Abused Drugs Sedatives (‘downers’): depress activity of the central nervous system § Drowsiness, relaxation, sleep § Increase GABA activity § Tolerance develops quickly § High risk of dependence § E.g., Xanax, Valium § Barbiturates vs benzodiazepines DRUG CLASSES: ALCOHOL  Alcohol Alcohol: most commonly used drug § Euphoria, relaxation, lowered inhibitions § Increase GABA activity, then stimulates endorphin and dopamine receptors § Tolerance develops gradually § Moderate-high risk of dependence § Biphasic effect  Alcohol Myopia Narrow focus on cues related to a person’s current desires and impulses while ignoring everything else Youth particularly susceptible Protracted development of frontal lobes DRUG CLASSES: MARIJUANA  Commonly Abused Illegal Drugs Marijuana: made from the leaves and buds of the Cannabis plant § Euphoria, relaxation, distorted sensory experiences, paranoia § THC mimics brain chemicals (anandamide) involved in sleep and memory by binding to cannabinoid receptors § Tolerance develops slowly § Lower risk of dependence § Stimulates hunger; reduces pain Marijuana Effects on the Brain Impairs memory, executive functioning, and motor coordination § Worse memory, attention, and decision- making than controls § Altered brain activity compared to controls even when successfully completing tasks § Distribution of cannabinoid receptors in the brain correspond to cognitive deficits  Marijuana: Good or Evil? Legalization in Canada took place in 2018 Manitoba has set the legal age for use, purchase, and possession of marijuana at 19