PSY 241 Lecture 12

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  1. Biological Rhythms Examples
    • 28 day menstrual cycle in females
    • Mood changes across the seasons (Winter vs. Spring)
  2. Circadian rhythms
    Biological rhythms that fluctuate about ever 24 hours
  3. Circadian cycle functions
    • Sleep/Awake pattern
    • Body Temperature
    • Growth Hormones
    • Stress Hormones
  4. Would circadian rhythms occur without any indicators of time and daylight?
    • Yes
    • These rhythms are endogenous (generated from within)
  5. Would rhythms still follow a 24 hours cycle without any indicators of time and daylight?
  6. Without external time cues, the awake/sleep cycle show...
    a slightly longer cycle as a result an individual wakes up later and later
  7. Free-running rhythm
    A rhythm that occurs when no stimuli reset or alter the rhythm
  8. What resets circadian rhythms?
    Sun light
  9. Zeitgeber
    Stimulus that resets the circadian rhythm
  10. Zeitgeber Examples
    • Light (in land organisms)
    • Tidal waves (in sea organisms)
    • Exercise
    • Noise
    • Meals
    • Temperature of environment
  11. Suprachiasmatic Nucleus (SCN)
    Region of brain serves as biological clock that maintains circadian rhythms to a 24 hour period
  12. Neurons in the SCN are _______________ during the day and _______________ during the night.
    Neurons in the SCN are very active during the day and show low activity during the night.
  13. What do SCN lesions do?
    • Disrupt hormone release and sleep-wake cycles
    • Without SNC, you get a free-running rhythm
  14. Retinohypothalamic path
    • Small portion of the optic nerve extends directly from retina to SCN
    • Retina input does not come from rods and cones
    • Input comes from retinal ganglion cells with melanopsin
    • Ganglion cells respond to light
  15. How much time is used from sleeping?
    • 175,000 hours in lifteime
    • 7,291 days
    • 243 months
    • 20 years
  16. Electroencephlogram (EEG)
    • Measures electrical activity recorded from electrodes attached to person's scalp
    • Measures gross electrical activity of the neocortex or "brain waves"
  17. Electrooculogram (EOG)
    Records eye movements
  18. Electromyogram (EMG)
    Records physiological activity of muscles
  19. Stage 1 Sleep
    • Irregular frequency and smaller amplitude
    • Vertex spikes, or sharp waves
    • Heart rate slows, muscle tension reduces, eyes move about
    • Lasts several minutes
    • Image Upload 1
  20. Stage 2 Sleep
    • Defined by waves of 12 to 14 Hz that occur in bursts, called sleep spindles
    • K-complexes appear - sharp negative EEG potentials
    • Image Upload 2
  21. Stage 3 sleep
    • Early:
    • Continued sleep spindles as in stage 2
    • Defined by appearance of large-amplitude, very slwo eaves called delta waves
    • Delta waves occurs about once per second

    Late: Delta waves present half the time

    Image Upload 3
  22. REM sleep
    • Follows SWS
    • Active EEG with small-amplitude, high-frequency waves, like an awake person
    • Muscle relaxed - paradoxical sleep
    • Increased activity of sympathetic nervous system

    Image Upload 4
  23. Typical night of adult sleep
    • Sleep time ranges: 7-8 hours
    • 45-50% stage 2, 20% REM sleep
    • Cycles last 90-110 minutes
    • Cylces early in night have more stage 3 SWS 
    • Later cycles have more REM sleep
  24. Slow-Wave vs. REM Sleep
    Image Upload 5
  25. REM is ______________ during infancy and __________________ through adulthood.
    REM is at higher levels during infancy and decreases through adulthood.
  26. Total daily sleep ____________ with age.
    Total daily sleep decreases with age.
  27. Reticular formation
    Ascending axons to brain, descending axons to spinal cord

    • Ascending axons send excitatory projections to hypothalamus, thalamus, basal forebrain, cortex
    • Release glutamate
    • Damage = coma or hypersomnolence (excessive sleeping)

    Descending axons associated with motor control (maintaining muscle tone)

    Stimulate and you awaken individuals or increases alertness in awake individuals
  28. Acetylcholine
    • Basal forebrain and brainstem have large groups of cholinergic neurons
    • Promote wakefulness and REM sleep
    • Participate in learning, memory, cognition
    • Ascending projections to cortex and hippocampus
    • Basal forebrain contains GABA neurons that inhibit GABA neurons inthe cortex, providing more activity
  29. Norepinephrine
    • Cell bodies in locus coeruleus (LC)
    • Ascending projections to cortex
    • Stimulate arousal
    • Increase NE, increase retention of recent memories and wakefulness
    • Neurons silent during sleep
  30. Serotonin
    • 15 different receptors
    • Cell bodies in Raphe Nuclei (several - dorsal, median, caudal, rostral)
    • Ascending projections to cortex
    • Promote wakefulness, suppress REM sleep
    • Neurons silent during sleep
    • Antideppresants increase wakefulness and suppress REM sleep
  31. Dopamine
    • Wake-promoting effects
    • Give drugs that block dopamine and people get sleepy
    • Parkinson's get sleepy
    • Ventral tegmental area and substantia nigria cell firing does not respond with sleep and wakefulness
  32. Histamine
    • Produces excitatory effects throughout brain
    • Originate from mammillary body (posterior to hypothalamus)
    • High during arousal and alertness, silent during sleep
    • Antihistamines produce drowsiness if they cross blood-brain barrier
  33. Orexin (hypocretin)
    • Peptide synthesize in lateral and posterior hypothalamus
    • Projections to mammillary body and locus coeruleus
    • Promotes wakefulness and suppress NREM and REM
    • Keeps you awake rather than wake you up
    • Lack of peptide = narcolepsy (trouble severe sleepiness and cataplexy
  34. Ultradian
    • Rhytmic biological event whose period is shorter than circadian
    • severeal minutes-several hours
    • Ex: Feeding
  35. Infradian
    • Rhythmic biological event whose period is longer than circadian
    • Ex: 28-day menstrual cycle
  36. 4 Biological functions of Sleep
    • Energy conservation
    • Niche adaption
    • Body restoration
    • Memory consolidation
  37. 4 Interacting neural systems that underlie sleep
    • Forebrain system - generates slow-wave sleep
    • Brainstem system - activates sleeping forebrain into wakefulness
    • Pontine system - triggers REM sleep
    • Hypothalamic system - coordinates other 3 brain regions to determine which state we're in
  38. Example Symptoms of Narcolepsy
    • Intense attacks of sleep that last 5-30 minutes
    • Exhibit normal sleep pattern at night but suffer abrupt, overwhelming sleepiness during the day
  39. What gene is thought to be affected with people with Narcolepsy?
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PSY 241 Lecture 12
2013-04-13 18:41:55
Sleep arturo zavala psychobiology

Sleep arturo zavala psychobiology
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