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2011-10-21 00:46:17
Wakefulness Sleep

Rhythms of Waking & Sleeping, Stages of Sleep & Brain Mechanisms, Why Sleep?
Show Answers:

  1. Endogenous circannual rhythm
    Self generated rhythm that lasts about a year
  2. Endogenous circadian rhythm
    Self generated rhythm that lasts about a day
  3. Zeitgeber
    • Stimulus that resets circadian rhythms
    • Ex: Light, tide, noise, temperature..
  4. Jet lag
    Disruption of circadian rhythms due to crossing time zones
  5. Cortisol
    • Adrenal horomone
    • Prolonged elevation of cortisol damages neurons in the hippocampus which is important for memory
  6. Curt Richter
    • Introduced idea that the brain generates its own rhythms
    • A biological clock
  7. Suprachiasmatic nucleus (SCN)
    • Provides control of circadian rhythms for sleep/temperature
    • Damage leaves rhytm inconsistent/no longer synced to light/dark patterns
  8. Melanopsin
    • Photopigment from retinal ganglion cells
    • Respond to light even without rods/cones
    • Receive input from rods/cones
    • See toward the periphery
    • Respond to light slowly, turn off slowly when light decreases
  9. Melatonin
    • Released by pineal gland
    • Influences circadian/circannual rhythms
    • Is secreted at night- makes us sleepy 2-3 hrs before bed
  10. Coma
    • Extended period of unconsciousness
    • Steady low level of brain activity
  11. Vegetative State
    • Decreased brain activity
    • Periods of sleep/periods of arousal
    • Limited responsiveness
    • Ex: Increased heart rate to pain
  12. Minimally Conscious State
    • Decreased brain activity
    • Brief periods of purposeful actions
    • Limited speech comprehension
  13. Brain Death
    • No sign of brain activity for 24+ hours
    • No response to any stimulus
  14. Polysomnograph
    EEG + Eye movement records
  15. Alpha waves
    • Rhythm of 8-12 brain waves per second
    • Associated with relaxation
  16. Sleep Spindle
    • 12-14 Hz waves during bursts
    • Lasts 1/2 second
    • Results from interaction between thalamus/cortex cells
  17. K-Complex
    • Sharp high amplitude wave
    • Followed by small, slow, positive wave
    • Most common in stage 2 of sleep
  18. Slow-Wave Sleep (SWS)
    • Stages 3+4
    • Slow, large amplitude brain waves
  19. Paradoxical Sleep
    Deep sleep in some ways, light in others
  20. Rapid Eye Movement (REM)
    • Light
    • Paradoxical sleep
    • Regular, low voltage fast waves
    • Increased neuronal activity
    • Deep
    • Head muscles are most relaxed
  21. Pontomesencephalon
    • Part of reticular formation
    • Contributes to cotrical arousal by axons releasing acetylcholine/glutamate in the basal forebrain/thalamus
  22. Locus coeruleus
    • Dark blue space
    • Small structure in the pons
    • Inactive most of the time
    • Bursts of impulses in response to emotional/meaningful events
    • Silent during sleep
  23. Histamine
    • Produced excitation throughout brain
    • Cells that release histamine are active during arousal
    • Less active around bedtime/early morning
  24. Orexin
    • Peptide neurotransmitter
    • Axons release it from basal membrane
    • Necessary for staying awake
  25. Basal forebrain
    • Cells provide axons that extend throughout the thalamus/cerebral cortex
    • Some release acetylcholine = exictatory/tends to increase arousal
  26. An increase in GABA..
    prevent its axons from spreading stimulation to other areas
  27. PGO Waves
    • REM sleep is associated with a distinctive pattern of high amplitude electrical potentials
    • Waves first detected in pons, thalamus, then occipital cortex
  28. Insomnia
    Inadequate sleep
  29. Sleep apnea
    • Impaired ability to breathe while sleeping
    • Caused by genetics, hormones..
  30. Narcolepsy
    • Frequent periods of sleepiness during the day
    • 1) Sudden attack of sleepiness
    • 2) Occasional muscle weakness- cataplexy
    • 3) Sleep paralysis
    • 4) Hypnagogic hallucinations - dreamlike experiences
    • Treatment: Stimulant drugs (Ritalin)
  31. Periodic Limb Movement Disorder
    Repeated involuntary movement of the legs/arms
  32. REM Behavior Disorder
    Move around a lot and act out their dreams
  33. Night Terrors
    • Intense anxiety
    • occurr during NREM
    • More common in children
  34. Why do we sleep?
    Conserve energy
  35. Activation-Synthesis Hypothesis
    Dream represents the brain's effort to make sense of sparse and distorted information
  36. Clinicoanatomical hypothesis
    Dreams begin with arousing stimuli that are made in the brain combined with recent memories and any info the brain is receiving from the senses