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PY460: Physiological Psychology. Chapter 9: Rhythms of Wakefulness & Sleep Rhythms of Waking & Sleeping Stages of Sleep and Brain Mechanisms Why Sleep? Why REM? Why Dreams?. Slide 2 : Natural Cycles of Biological Activity. [Clip: The Brain - Sleep & Circadian Rhythms]

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py460 physiological psychology

PY460: Physiological Psychology

  • Chapter 9: Rhythms of Wakefulness & Sleep
    • Rhythms of Waking & Sleeping
    • Stages of Sleep and Brain Mechanisms
    • Why Sleep? Why REM? Why Dreams?
slide 2 natural cycles of biological activity
Slide 2: Natural Cycles of Biological Activity
  • [Clip: The Brain- Sleep & Circadian Rhythms]
  • Curt Richter (1920’s)- biological beings have naturally occurring biological cycles largely independent of the outside world.
    • Challenge to behaviorism in the mid-1900’s
      • why?
  • Endogeneous cycles- of evolutionary value
    • anticipation of upcoming conditions
      • migration mating
      • storage
    • “migratory restlessness” in willow warblers
      • occurs despite lack of environmental cues (light)
slide 3 specific endogenous cycles
Slide 3: Specific Endogenous Cycles
  • Endogenous Circannual Rhythms
    • internal cycles that prepares animal for seasonal changes
      • storage of fats, hibernation, humans???
  • Endogenous Circadian Rhythms
    • internal cycles (rhythms) that prepares animal for changes that last about a day.
  • Most Familiar Rhythm? Sleep & Wakefulness!
    • Others include: core body temperature, frequencyt of eating & drinking, hormonal secretion, chemical sensitivities (drugs).
slide 4 zeitgebers keeping rhythms in synchrony
Slide 4: Zeitgebers: Keeping Rhythms in Synchrony
  • All rhythms typically stay in synchrony suggesting a “master biological clock” exists (more on this in a bit).
  • We know that our free running rhythms are often greater than 24 hrs. (24.25- 24.75 hrs.).
  • Why don’t we (and other animals) get “off-pace” with the 24 hours daily cycle?
  • AH…LIGHT the primary Zeitgeber (say like a German)- resets the master clock.
    • other “time keepers”- noises, meals, temperature variations
slide 5 mammoth cave etc altering the biological clock
Slide 5: Mammoth Cave etc.- Altering the Biological Clock?
  • What is humans traveled to a planet with a different daily cycle (say 20-30 hrs)? How would we adjust?
  • Mammoth Cave study (1963).
    • A month in a cave (temperature and light controlled).
    • 28 hr days, (9 hrs sleep). What would happen to their cycle?
    • Findings: Continued maintenance of the 24 hour clock… subjects could force themselves into the schedule but, bodies maintained original rhythms.
  • Study 2: 12 volunteers in a cave… clock varied between 24-22 hours..
    • At 23 hrs most subjects adjusted, only 1 @ 22 hrs.
  • Bottom Line- significant changes in daily rhythms very difficult to make
slide 6 disturbing the biological clock
Slide 6: Disturbing the Biological Clock
  • Our free running clock runs longer than 24 hrs, but our days are 24 hrs… daily readjustment keeps us in sync...
  • What would changes might cause de-synchrony between biological clock & hourly clock?
  • WEEKENDS (No.1)--
    • Fewer time constraints… Often follow bioclock---Go to bed later, sleep in…get up.. Reset clock.. Go to bed later than before.. Get up little later.. Reset clock-- by Monday, bioclock hours behind the hourly clock
  • SHIFT WORK-- night shifts, or irregular pattern in schedule lead to irregular sleeping patterns, temperature often maintain daily pattern, health & safety issues.
    • Particularly bright light somewhat effective in competing with day time light
slide 7 more disturbances in the bioclock
Slide 7: More Disturbances in the Bioclock
  • JET LAG- rhythm disturbance caused by crossing times zones..
    • Traveling west (PA to LA) (stay up later, sleep in… gain hours )(27 hrs… tend to be ok-- more natural to be awake a little later.. Sleep in)
    • Traveling East (LA to PA) (lose hours).
slide 8 suprachiasmatic nucleus the bioclock
Slide 8: Suprachiasmatic Nucleus- the bioclock
  • Suprachiasmatic Nucleus- area in the hypothalamus, just above the optic chiasm (nerve).
    • Rentinohypothalamic pathway
    • Autorhythmic quality may drive circadian rhythms.
    • Biological clock stops if damaged or Optic Nerve projecting to SCN is damaged
    • Extremely sensitive to light (even in blind moles!)
      • SCN reset to light
        • Biochemical action unclear.. Protein production?
slide 9 scn melatonin
Slide 9: SCN & Melatonin
  • Melatonin- hormone important in regulating sleepiness & wakefulness
    • secreted near the end of a waking cycle.. A few hours before typical bed time.
  • Pineal Gland- secretes melatonin release at the command of SCN.
    • Taking melatonin supplements (.5 mg) in the afternoon---> phase-advances circadian rhythm (jet lag?)
    • Taking melatonin in morning phase-delays circadian rhythm
  • A note of warning-- little extended research in area.
slide 10 the brain during sleep nrem sleep only
Slide 10: The Brain During Sleep (NREM Sleep only)
  • EEG- increased wave size= greater synchrony between two close sites on cortex.
    • Provides an objective measure of sleep and wakefulness
  • Stages of Sleep- characterized by a type of wave
  • Awake/Relaxed- Alpha Waves, Beta Waves
  • Stage 1: freq. irregular, jagged waves (Theta)
  • Stage 2: Sleep Spindles (12-14hz) & K-complexes
    • K-complexes evoke by sudden stimuli (noise etc)
  • Stage 3 & 4: Slow wave sleep (SWS) (2hz waves)
          • big slow waves (delta) indicating high synchrony
          • reduced sensory input to cortex… “less noise”
          • see wave and stone analogy (p. 254)
slide 11 synchrony eeg
Slide 11: Synchrony & EEG

Choose the stage &

name the characteristics

  • Big slow 1/2 sec waves; highly synchronous action
  • Alpha & beta waves (smaller amplitude) regular and choppy respectively
  • sleep spindles & k-complexes frequent here
slide 12 rem sleep paradoxical sleep
Slide 12: REM Sleep/Paradoxical Sleep
  • Michel Jouvet, Kleitman & Aserinsky- scientists notice that during certain intervals of sleep
    • high levels of brain activity (almost looked awake)
    • no bodily movement though, in fact most relaxed state of postural muscles
    • rapid eye movement in humans
    • increased “genital activity”
    • called it “paradoxical” and “REM” sleep, respectively.
  • REM sleep-- low voltage, irregular waves suggestive of considerable brain activity
slide 13 cycling through the stages
Slide 13: Cycling through the stages
  • Progression through the stages @ night.
  • Stage 3 to 4 longest early on
  • progressive lengthening of REM toward the final hours
  • REM strongly associated with dreaming.. But apparently not the only dream stage
slide 14 brain structures in wakefulness arousal
Slide 14: Brain Structures in Wakefulness & Arousal
  • The Reticular Formation- structures whose length extends from the spinal cord up to the forebrain..
    • Widely connected to the sensory systems
          • may easily respond to slightest sensory impulse
    • Spontaneous pulsing activity regulating arousal even with little external stimuli
    • Cutting through the midbrain immediately reduces arousa
  • Pontomesencephalon-
  • Locus Coeruleus- emits arousing bursts to meaningful events such as reinforcement/arousal and may assist in memory of important events.
    • Inactive during sleep-->little memory??
slide 15 arousing brain structures continues
Slide 15: “Arousing Brain Structures” continues
  • Basal Forebrain(anterior and dorsal to hypothalamus)
    • Damage leads to decreased arousal, impaired learning & attention
    • most damaged by degradation of Alzheimer’s
    • Acetylcholine- an arousing neurotransmitter in BF

GETTING TO SLEEP- Inhibiting Arousal Systems

  • Adenosine (declines during sleep)- a neuromodulator that accumulates over the course of the day and blocks ACh.
  • Caffeine- blocks Adenosine--> incr. Arousal (ACh)
    • interferes the whole day… even a morning cup of “Joe”.
  • Prostaglandins- (decline during sleep)
slide 16 brain functions in rem sleep pgo waves
Slide 16: Brain Functions in REM Sleep: PGO Waves
  • The first indication of approaching REM sleep are short burst from the Pons, lateral Geniculate, & Occipital Cortex(PGO waves) (see text figure 9.12)
    • LG and OC critical for vision processes-- REM primarily a visual phenomenon?
  • First part of REM--- LG / OC manipulation
  • Latter-- more thalamus than just LG and the cerebral cortex… becomes a less visual phenomena.
  • Pons-- pulses related to sleep paralysis
    • damage to Pons cell to the spinal cord leads to disinhibtion of behavior during sleep (fig 9.13).
slide 17 abnormalities of sleep insomnias
Slide 17: Abnormalities of Sleep/Insomnias
  • Causes: many
      • caffeine, drugs, stress, temperatures
    • Onset insomnia
    • Maintenance Insomnia
    • Termination Insomnia
  • Irregularities in biorhythms
  • phase delayed
          • onset an issue
  • phase advanced
          • termination an issue
slide 18 other abnormalities of sleep
Slide 18: Other Abnormalities of Sleep
  • Sleep Apnea- inability to breath during sleep-- cuts sleep times in half in worst cases…. Linked to obesity
  • SIDS
  • Narcolepsy- intrusion of REM into “wakeful”states
    • sudden sleepiness during day
    • cataplexy- muslce weakness while awake
    • frequent sleep paralysis even during “twilight” states
    • Hypnogogic hallucinations on early onset.
  • PLMD- decr sleep paralysis (Pons?)
  • REM Bhvr Disorder-act out dreams (damage to pons & midbrain)
  • Night Terrors-screaming in terror during NREM sleep
  • Talking in Sleep (REM or NREM sleep)
  • Sleepwalking- strong genetic component
          • awakening sleep walkers
slide 19 what is sleep for theories on function
Slide 19: What is sleep for? Theories on Function
  • Repair & Restoration Theory- Sleep evolved to assist the body in repairing itself after the exertions of the day.
  • Going without sleep-- psychological effects (what are they?)
  • Physiological f/x: increased body temp, metabolic rate, appetite; decreased immune response.
  • Evolutionary Theory of Sleep- a form of mini-hibernation… we sleep when food is scarce and danger is greater.. Conserves energy when we can’t replenish it easily or safely.
    • Temp decreases, metabolism decreases
    • Carnivores/Herbivores sleep patterns
slide 20 the function of rem what is it good for
Slide 20: The Function of REM- What is it good for?
  • Abundance of REM during early childhood
          • neuronal connections?? (see fig 9.17, pg276)
  • REM varies from person to person..
      • It has been suggested we could go without it (Horne, 1988).
  • So what if we do go without?? (Dement, 1960)
    • Dement woke subject for a week every time went into REM stage
      • effects: decreased time to REM sleep.. Up to an average of 26 times of waking per night by 7 day up from 12 on the first
      • effects: increased anxiety, decreased concentration, personality change, increased appetite/weight gain.
    • Cat research
  • other hypotheses on roles of REM sleep
    • REM assists in memory formation
    • Increased oxygen delivery to retina’s
slide 21 a biological perspective on dreaming
Slide 21: A Biological Perspective on Dreaming
  • Freud- Dreaming symbolic of unconscious wishes (“wish fulfillment”)
  • Activation-synthesis hypothesis- various external stimuli activate structures in the brain and are synthesized by the brain into a “story”.
      • Is this sensible to you… how have external stimuli been incorporated into your dreams?
  • Another version.. The brain is active during REM sleep but starved for stimuli.. In this absence---> borrows aspects from memory to construct a story.
    • Flying sensations (vesitbular pulses)
    • Slow movement dreams (postural muscles frozen)
  • Clinico-Anatomical Hypothesis
      • Dreams begin with arousing stimuli from the brain’s own motivations, memories, and arousal
      • Does not compete with visual input or censorship by prefrontal cortex