PSY 241 Lecture 12

  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?
Card Set
PSY 241 Lecture 12
Sleep arturo zavala psychobiology