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Bio Psych Exam 3 Pt3
Ch. 9: Wakefulness & Sleep
| Question | Answer |
|---|---|
| What are Circadian Rhythms? | Daily, cyclical changes in behavioral and physiological processes (ie: wakefulness and sleep, body temperature, hormone secretions, frequency of eating and drinking, urination, etc); endogenous; differ (to some degree) between indvl's & change as we age |
| Why do we have Circadian Rhythms? Naturally, what duration do they have? What keeps them from having this duration? | Circadian Rhythms keep our internal workings in phase with the outside world; they would naturally be ~25 hours long, but Zeitgebers reset them. |
| What does Endogenous mean? | Generated internally within the body; self-regulated (circadian rhythms are endogenous) |
| What is a Zeitgeber? | A stimulus that resets circadian rhythm (ie: light, exercise, meals, noise, temperature); without a Zeitgeber, our circadian rhythms would be ~25 hours |
| What things can disrupt normal patterns of sleeping and waking? | Shift work (doctors, people who work night shifts), changing time zones, living far from the equator, astronauts, working on a submarine, being an undergraduate (ha) |
| How well do people adjust to disruptions in these patterns of sleeping and waking? | People adjust better to small differences than large; but people who have disturbances constantly usually fail to adjust completely |
| What is Jet Lag? | Disruption of the circadian rhythms due to crossing time zones; a mismatch between internal circadian clock and external time; causes sleepiness during the day, sleeplessness at night, impaired concentration |
| What is the Suprachiasmatic Nucleus (SCN)? | Part of the hypothalamus; acts as the time keeper for circadian rhythms for sleep and body temperature; generates these rhythms in a genetically controlled, unlearned manner; damage to SCN disrupts these rhythms; an SCN cell fires APs in rhythmic patterns |
| What is the most important Zeitgeber for the SCN? | The sun! |
| Describe why the SCN is reset by light. | The SCN is located just dorsal (supra) to the optic nerve chasm; it receives input from the optic nerve from ganglion cells that have a distinct type of photopigment called melanopsin, which responds to diffuse light in the periphery (ambient light) |
| What is Melanopsin? | A distinct type of photopigment that responds to diffuse light in the periphery; it does not require rods or cones; not a visual sense, just a sense of ambient light; helps reset SCN, which receives input via optic nerve from ganglion cells w melanopsin |
| Describe the role of the Pineal Gland. | The Pineal Gland is an endocrine gland located posterior to the thalamus; it is influenced by the SCN; it secretes melatonin (which increases sleepiness) |
| What is Melatonin? | Hormone that increases sleepiness; secreted by the Pineal Gland 2-3 hours before bedtime; resets the biological clock through receptors in the SCN; can be administered as a sleep aid (but the body builds a tolerance and will stop secreting it on its own) |
| Describe the Genetic Regulation of Circadian Rhythms. | Two genes (called Period & Timeless) that each produce a protein (called Per & Tim) that promotes sleepiness |
| Describe the cycles of Per & Tim. | Complex feedback patterns cause these proteins to build up during the day & then decrease at night (bright light activates chemicals that break down Per & Tim). |
| What happens if there is a mutation on either the Period or Timeless gene? | The mutation would influence sleep patterns. |
| What are Per & Tim? | Per & Tim are two proteins produced by the genes Period & Timeless that promote sleepiness. |
| What are Period & Timeless? | Period & Timeless are two genes that produce the proteins Per & Tim, which promote sleepiness. |
| What is Adenosine? | Adenosine is a purine NT; high levels of it promote sleepiness |
| Describe the cycle of Adenosine. | Adenosine builds up throughout the day and declines during sleep. |
| Describe the biological relationship between Caffeine and Adenosine. | Caffeine binds to Adenosine receptors, and blocks Adenosine from binding (acts as an Adenosine antagonist); Caffeine tolerance arises because your body builds new Adenosine receptors. |
| How does Caffeine affect your sleepiness or wakefulness? | By acting as an Adenosine antagonist (Adenosine causes sleepiness) |
| What is sleep? | Sleep involves an interruption of conscious experience, but is not a passive state of inactivity; marked by a moderate decrease in brain activity & response to external stimuli; brain actively produces sleep; differs from comas/vegetative states |
| What is an Electroencephalograph (EEG)? | An indirect measure used to monitor brain activity during sleep; reveals several distinct phases of sleep; when combined with eye movement data, forms a polysomnograph |
| What is a Polysomnograph? | Combination of EEG and eye movement data that helps identify the different stages of sleep |
| What are Alpha Waves? | A steady series of brain waves that are characteristic of relaxation (awake stage of relaxation, beginning to feel tired) |
| Describe Stage 1 sleep. | Sleep has just begun; EEG is dominated by irregular, jagged, low voltage waves |
| Describe Stage 2 sleep. | Contains sleep spindles & K complexes |
| What do we call Stages 3 & 4 of sleep. | Slow Wave Sleep (SWS) |
| What stages of sleep make up Slow Wave Sleep (SWS)? | Stages 3 & 4 |
| Describe Slow Wave Sleep (SWS). | Deep Sleep; EEG recording of slow, large amplitude waves; lower HR, breathing rate & brian activity; highly synchronized neuronal activity; predominates early & the length of SWS decreases further into the night (with increasing cycles) |
| Describe REM Sleep. | AKA Paradoxical Sleep (bc it looks like wakeful activity); rapid eye movements; EEG waves are irregular, low-voltage, & fast; muscle paralysis; strongly associated with dreaming (but reported in other states); PGO waves appear; predominates later in night |
| What triggers REM Sleep? | Activity in the Pons triggers REM (causes muscle paralysis & PGO waves originate here); ACh (and drugs that stimulate ACh receptors) triggers REM; Serotonin & NE interrupt REM |
| Why do four 30-minute naps not equate to 2 hours of uninterrupted sleep? | The length of SWS and REM stages per sleep cycle changes with increasing cycles; SWS predominates early and length REM increases in later cycles; less REM in four 30-minute naps |
| How long does an average sleep cycle last? | ~90 minutes |
| What is NREM sleep? | Any stage of sleep (1-4) that is not REM |
| Describe the role of the Pontomesencephalon. | Promotes wakefulness; part of the Reticular Formation (in Brainstem); axons extend to Thalamus & Basal Forebrain where they release ACh and Glutamate (which increases cortical arousal) |
| What would stimulation to the Pontomesencephalon do to a sleeping person? To a waking person? | It would awaken a sleeping individual and increase alertness in those who are already awake |
| Describe the role of the Locus Coeruleus. | Small structure in the Pons (part of Brainstem) that promotes wakefulness; its axons release NE, which increases cortical arousal |
| Describe the role of the Hypothalamus. | The Hypothalamus releases the NTs Histamine & Orexin, which both promote wakefulness |
| What is Histamine? | Neurotransmitter released by the Hypothalamus; promotes wakefulness; produces widespread excitatory effects throughout the brain |
| What is Orexin? | Peptide NT released by the Hypothalamus; promotes wakefulness; responsible for the ability to stay awake; excites ACh-releasing cells in the Basal Forebrain |
| What is Paradoxical Sleep? | Another name for REM sleep due to the fact that it looks like activity during wakefulness |
| What is another name for REM Sleep? | Paradoxical Sleep |
| What is the Basal Forebrain and its role? | Area anterior & dorsal to Hypothalamus; includes cell clusters that promote both wakefulness & sleep; axons release (excitatory) ACh that increases arousal, learning & attention & shifts NREM into REM; also release GABA that inhibits thalamus & cortex |
| What is GABA? | GABA is the primary inhibitory NT that actually triggers sleep (other things just make you sleepy) |
| Describe the effects of GABA. | Many bodily functions slow down during sleep (temperature, metabolic rate, neural activity); but the effects of GABA can be highly localized (one part of the brain is inhibited while others remain awake... like in dolphins) |
| What are PGO waves? | (PGO=Pons-Geniculate-Occipital); distinctive pattern of waves associated with REM sleep; activate the visual pathway (they follow the visual pathway from Pons->LGN->Occipital Lobe, but with no input from eyes); may be related to vivid imagery in dreams |
| When do PGO waves occur during wakefulness and what is their effect? | PGO waves can occur during waking if you are sleep deprived, and may be the cause of hallucinations |
| Describe the role of the Pons. | Pons is key for REM sleep; it originates PGO waves and sends messages to the spinal cord (inhibits motor neurons & prevents movements during REM) |
| What can lesions to a particular region of the Pons do? | Lesions to a particular region of the Pons decreases REM sleep |
| Which NTs trigger REM and which NTs interrupt REM? | ACh triggers REM; Serotonin and NE interrupt REM |
| What is Insomnia? What are its causes? | Sleep disorder marked by difficulty falling asleep or inadequate sleep; can be caused by stress, epilepsy, Parkinson's, depression & other psychiatric conditions, medication, disruptions to circadian rhythm, sleep apnea (difficulty breathing during sleep) |
| How does Sleep Apnea (or waking up during the night) affect the relative amount of REM sleep? | Causes more SWS and less REM |
| Describe the link between Sleep Disruption & Mental Illness. | There is a clear link between the two, but the direction of causality is unclear (sleep could cause depression or vice versa) |
| What is Narcolepsy? | Sleep disorder marked by intrusions of the REM state into wakefulness; characterized by 4 symptoms (most people don't show all 4): gradual or sudden attacks of sleepiness, cataplexy, sleep paralysis & hypnagogic hallucinations |
| What causes Narcolepsy? | Deficit in Orexin production |
| What is Cataplexy? | A symptom of Narcolepsy; sudden muscle paralysis while awake that is often triggered by excitement or strong emotions |
| What is Sleep Paralysis (as a symptom of Narcolepsy)? | Inability to move while asleep or waking up |
| What are Hypnagogic Hallucinations? | A symptom of Narcolepsy; dreamlike experiences that are difficult to distinguish from reality |
| Name 3 types of Sleep Disorders (besides Insomnia & Narcolepsy). | Night Terrors, Sleep Talking, and Sleep Walking |
| Describe Night Terrors. | Intense anxiety upon waking up; usually occurs in NREM sleep; more common in children |
| What do you know about Sleep Talking? | A sleep disorder that occurs during both REM & NREM sleep |
| What do you know about Sleep Walking? | A sleep disorder that runs in families; occurs mostly during SWS (Stages 3 & 4); it is not the same as REM Behavior Disorder |
| What is REM Behavior Disorder? | Marked by vigorous movements during REM sleep (absence of usual muscle paralysis); acting out dreams; occurs mostly in older men w brain diseases like Parkinson's; damage to Pons (too little inhibition of spinal neurons that control muscle movements) |
| What are 3 reasons why we sleep? | 1. To conserve energy 2. To enable restorative processes 3. To improve memory |
| How does sleep help conserve energy? | We have a decrease in body temperature (of 1-2 degrees C in mammals) and decrease in muscle activity |
| What evidence supports the theory that sleep helps conserve energy? | We sleep during periods when we are less efficient (ie: primates rely on visions, which is less effective at night); animals increase their sleep during food shortages (analogous to hibernation) |
| How does the number of hours an animal spends looking for food influence its sleep habits? | Grazing animals that spend much of their day finding/eating low-calorie food spend much less time asleep; Animals like humans get a moderate amount of sleep; Animals like bats & cats that eat big meals relative to their size sleep a ton |
| How does sleep help enable restorative processes? | During sleep, proteins are rebuilt in the brain, energy supplies are replenished, and muscles rest. |
| What does sleep deprivation cause? | Impaired concentration, irritability, hallucinations, tremors, unpleasant mood, decreased immune system functioning; being awake for 24 hours leads to driving performance as being at the legal limit of drunk (evidence for sleep as restorative process) |
| How does sleep help improve memory? | Performance on a newly learned task up after sleep, declarative memory (facts/knowledge) become stronger; during sleep, upped brain activity in area of brain activated by task (relates to improvement next day); new learning=more sleep spindles; replay |
| When does replay occur? What might it help explain? | Primarily during SWS and REM (which likely explains increase in brain activity); could also underlie some aspects of dreaming |
| Which brain region plays an important role in replay? | Hippocampus |
| Why is it difficult to study dreaming? | Subjects often don't remember, and even if they do there is no way to verify; also impossible to do animal research |
| Which stage of sleep is dreaming most strongly tied to? | REM sleep |
| What are the two theories of dreaming? | 1. Activation-Synthesis Hypothesis 2.Clinico-Anatomial Hypothesis |
| What is the Activation-Synthesis Hypothesis? | Idea that a dream represents the brain's effort to make sense of spars/distorted information; brain tries to make sense of seemingly random input; may be related to replay; incorporation of current sensory information |
| What are some ways Activation-Synthesis Hypothesis thinks dreams incorporate our current sensory information? | Sensations of flying or falling during sleep (because of laying down); lack of control in dreams (due to REM-induced paralysis); noises & talking can also influence the dream |
| What is the Clinico-Anatomical Hypothesis? | Dreams are similar to normal thinking, just in an unusual context; Changes in brain activity that accompany sleep explain the nature and content of our dreams; if we manipulated activity in these regions while awake, our thoughts would be just like dreams |
| What changes in brain activity does the Clinico-Anatomical Hypothesis say affect our thoughts? | Reduced activity in Prefrontal Cortex & Primary Sensory Regions/ Increased Activity in Parietal Cortex, Amygdala, Hypothalamus, & Occipital Regions (outside V1) |
| What is one piece of evidence that the Clinico-Anatomical Hypothesis says proves that manipulating activity in these regions while waking would make our thoughts like dreams? | Hallucinations during Sensory Deprivation |
| What is a K-Complex? | A distinct type of brain wave that is characteristic of Stage 2 Sleep; sharp, high-amplitude negative wave followed by a smaller positive wave |
| What is a Sleep Spindle? | A distinct type of brain wave that is characteristic of Stage 2 Sleep; 12 to 14 Hz waves during a burst that lasts at least half a second |
Created by:
Kelsey20
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