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Biological Psychology, 5e

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  • 1. Biological Rhythms, Sleep, and Dreaming
  • 2. 14 Biological Rhythms, Sleep, and Dreaming
    • Biological Rhythms
    • Many Animals Show Daily Rhythms in Activity
    • The Hypothalamus Houses an Endogenous Circadian Clock
    • Animals Use Circannual Rhythms to Anticipate Seasonal Changes
  • 3. 14 Biological Rhythms, Sleep, and Dreaming
    • Sleeping and Waking
    • Human Sleep Exhibits Different Stages
    • The Sleep of Different Species Provides Clues about the Evolution of Sleep
    • Our Sleep Patterns Change across the Life Span
    • Manipulating Sleep Reveals an Underlying Structure
  • 4. 14 Biological Rhythms, Sleep, and Dreaming
    • What are the Biological Functions of Sleep?
    • At Least Four Interacting Neural Systems Underlie Sleep
    • Sleep Disorders Can Be Serious, Even Life-Threatening
  • 5. Many Animals Show Daily Rhythms in Activity
    • Circadian rhythms are those functions of a living organism that display a rhythm of about 24 hours.
    • Rhythms may be behavioral, physiological, or biochemical.
    • Diurnal —active during the light
    • Nocturnal —active during the dark
  • 6. Figure 14.1 How Activity Rhythms are Measured (Part 1)
  • 7. Many Animals Show Daily Rhythms in Activity
    • Circadian rhythms are generated by an endogenous (internal) clock.
    • A free-running animal is maintaining its own cycle with no external cues, such as light.
    • The period , or time between successive cycles, may not be exactly 24 hours.
  • 8. Figure 14.1 How Activity Rhythms are Measured (Part 2)
  • 9. Many Animals Show Daily Rhythms in Activity
    • A phase shift is the shift in activity in response to a synchronizing stimulus, such as light or food.
    • Entrainment is the process of shifting the rhythm.
    • The cue that an animal uses to synchronize with the environment is called a zeitgeber —“time-giver”
  • 10. The Hypothalamus Houses an Endogenous Circadian Clock
    • The biological clock is in the suprachiasmatic nucleus (SCN)— located above the optic chiasm in the hypothalamus.
    • Studies showed that circadian rhythms were disrupted in SCN-lesioned animals.
    • Isolated SCNs can maintain electrical activity synchronized to the previous light cycle.
  • 11. Figure 14.2 The Effects of Lesions in the SCN
  • 12. Figure 14.3 The Circadian Rhythm of Metabolic Activity of the SCN
  • 13. The Hypothalamus Houses an Endogenous Circadian Clock
    • Transplant studies proved that the endogenous period is generated in the SCN.
    • Hamsters with abolished circadian rhythms received an SCN tissue transplant from hamsters with a very short period, ~20 hours.
    • The rhythms were restored but matched the shorter period of the donor.
  • 14. Figure 14.4 Brain Transplants Prove that the SCN Contains a Clock
  • 15. The Hypothalamus Houses an Endogenous Circadian Clock
    • Circadian rhythms entrain to light–dark cycles using different pathways, some outside of the eye.
    • In amphibians and birds, the pineal gland is sensitive to light.
    • In mammals, light information goes from the eye to the SCN via the retinohypothalamic pathway .
  • 16. The Hypothalamus Houses an Endogenous Circadian Clock
    • The retinohypothalamic pathway consists of retinal ganglion cells that project to the SCN.
    • These ganglion cells do not rely on rods and cones.
    • Most of these retinal ganglion cells contain melanopsin , a special photopigment, that makes them sensitive to light.
  • 17. Figure 14.5 The Retinohypothalamic Pathway in Mammals
  • 18. Figure 14.6 Schematic Showing the Components of a Circadian System
  • 19. The Hypothalamus Houses an Endogenous Circadian Clock
    • Molecular studies in Drosophila using mutations of the period gene helped to understand the circadian clock in mammals.
    • SCN cells in mammals make two proteins:
    • Clock
    • Cycle
  • 20. The Hypothalamus Houses an Endogenous Circadian Clock
    • Clock and Cycle proteins bind together to form a dimer .
    • The Clock/Cycle dimer promotes transcription of two genes:
    • Period (per)
    • Cryptochrome (cry)
  • 21. The Hypothalamus Houses an Endogenous Circadian Clock
    • Proteins arising from per and cry bind to each other and to a third one, Tau.
    • The Per/Cry/Tau protein complex enters the nucleus and inhibits the transcription of per and cry .
    • No new proteins are made, until the first set degrades and the cycle begins again every ~24 hours.
  • 22. Figure 14.7 A Molecular Clock in Flies and Mice
  • 23. The Hypothalamus Houses an Endogenous Circadian Clock
    • Light entrains the molecular clock in different ways.
    • In flies, light reaches the brain directly and degrades a clock protein.
    • In mammals, melanopsin cells detect light and release glutamate in the SCN.
    • Glutamate triggers events that promote production of the Per protein, which in turn shifts the clock and the animal’s behavior.
  • 24. The Hypothalamus Houses an Endogenous Circadian Clock
    • Gene mutations show how important the clock is to behavior in constant conditions:
    • tau mutations—the period is shorter than normal
    • Double Clock mutants—arrhythmic
    • Single Clock mutants—period is longer than normal
  • 25. Figure 14.8 When the Endogenous Clock Goes Kaput
  • 26. The Hypothalamus Houses an Endogenous Circadian Clock
    • Some biological rhythms are shorter, such as bouts of activity, feeding, and hormone release.
    • These ultradian rhythms occur more than once per day.
    • Period length can be from minutes to hours.
  • 27. Animals Use Circannual Rhythms to Anticipate Seasonal Changes
    • Other biological rhythms are long, such as body weight, and reproductive cycles.
    • An endogenous circannual clock, separate from the SCN, runs at ~365 days.
    • Infradian rhythms occur less than once per day.
  • 28. Figure 14.9 A Hamster for All Seasons
  • 29. Sleeping and Waking
    • Sleep is synchronized to external events, including light and dark.
    • Stimuli like lights, food, jobs, and alarm clocks entrain us to be awake or to sleep.
    • In the absence of cues, humans have a free-running period of ~25 hours that varies with age.
  • 30. Figure 14.10 Humans Free-Run Too
  • 31. Figure 14.11 Oh, How I Hate to Get Out of Bed in the Morning
  • 32. Human Sleep Exhibits Different Stages
    • Electrical brain potentials can be used to classify levels of arousal and states of sleep.
    • Electroencephalography (EEG) —records electrical activity in the brain
    • Electro-oculography (EOG) —records eye movements
    • Electromyography (EMG)— records muscle activity
  • 33. Human Sleep Exhibits Different Stages
    • Two distinct classes of sleep:
    • Slow-wave sleep (SWS) —can be divided into four stages and is characterized by slow-wave EEG activity
    • Rapid-eye-movement sleep (REM) —characterized by small amplitude, fast-EEG waves, no postural tension, and rapid eye movements
  • 34. Human Sleep Exhibits Different Stages
    • The pattern of activity in an awake person contains many frequencies:
    • Dominated by waves of fast frequency and low amplitude (15 to 20 Hz).
    • Known as beta activity or desynchronized EEG
    • Alpha rhythm— occurs in relaxation, a regular oscillation of 8 to 12 Hz
  • 35. Human Sleep Exhibits Different Stages
    • Four stages of slow-wave sleep:
    • Stage 1 sleep —shows events of irregular frequency and smaller amplitude, as well as vertex spikes , or sharp waves
    • Heart rate slows, muscle tension reduces, eyes move about
    • Lasts several minutes
  • 36. Human Sleep Exhibits Different Stages
    • 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
  • 37. Human Sleep Exhibits Different Stages
    • Stage 3 sleep :
    • Continued sleep spindles as in stage 2
    • Defined by the appearance of large-amplitude, very slow waves called delta waves
    • Delta waves occur about once per second
  • 38. Human Sleep Exhibits Different Stages
    • Stage 4 sleep :
    • Delta waves are present about half the time
    • REM sleep follows:
    • Active EEG with small-amplitude, high-frequency waves, like an awake person
    • Muscles are relaxed—called paradoxical sleep
  • 39. Figure 14.12 Electrophysiological Correlates of Sleep and Waking
  • 40. Human Sleep Exhibits Different Stages
    • In a typical night of young adult sleep:
    • Sleep time ranges from 7-8 hours.
    • 45-50% is stage 2 sleep, 20% is REM sleep.
    • Cycles last 90-110 minutes, but cycles early in the night have more stage 3 and 4 SWS, and later cycles have more REM sleep.
  • 41. Figure 14.13 A Typical Night of Sleep in a Young Adult
  • 42. Human Sleep Exhibits Different Stages
    • Vivid dreams occur during REM sleep, characterized by:
    • Visual imagery
    • Sense that the dreamer is “there”
    • Nightmares are frightening dreams that awaken the sleeper from REM sleep.
    • Night terrors are sudden arousals from stage 3 or 4 SWS, marked by fear and autonomic activity.
  • 43. Figure 14.14 Night Terror
  • 44. The Sleep of Different Species Provides Clues about the Evolution of Sleep
    • REM sleep evolved in some vertebrates:
    • Nearly all mammals display both REM and SWS, except the echidna—a monotreme , or egg-laying mammal—that may not have REM sleep
    • Birds also display both REM and SWS sleep
  • 45. Figure 14.15 Amounts of Different Sleep States in Various Mammals
  • 46. The Sleep of Different Species Provides Clues about the Evolution of Sleep
    • Marine mammals do not show REM sleep, perhaps because relaxed muscles are incompatible with the need to come to the surface to breathe.
    • In dolphins and birds, only one brain hemisphere enters SWS at a time— the other remains awake.
  • 47. Figure 14.16 Sleep in Marine Mammals
  • 48. The Sleep of Different Species Provides Clues about the Evolution of Sleep
    • A sleep cycle is a period of SWS followed by one of REM sleep.
    • Most vertebrates show:
    • A circadian distribution of activity
    • A prolonged phase of inactivity
      • Raised thresholds to external stimuli
      • Characteristic posture
  • 49. Our Sleep Patterns Change across the Life Span
    • Mammals sleep more during infancy than in adulthood.
    • Infant sleep is characterized by:
    • Shorter sleep cycles
    • More REM sleep—50%, which may provide essential stimulation to the developing nervous system
  • 50. Figure 14.17 The Trouble with Babies
  • 51. Figure 14.18 Human Sleep Patterns Change with Age
  • 52. Our Sleep Patterns Change across the Life Span
    • As people age, total time asleep declines, and number of awakenings increases.
    • The most dramatic decline is the loss of time spent in stages 3 and 4:
    • At age 60 only half as much time is spent as at age 20—by age 90 stages 3 and 4 have disappeared.
  • 53. Figure 14.19 The Typical Pattern of Sleep in an Elderly Person
  • 54. Manipulating Sleep Reveals an Underlying Structure
    • Effects of sleep deprivation —the partial or total prevention of sleep:
    • Increased irritability
    • Difficulty in concentrating
    • Episodes of disorientation
    • Effects can vary with age and other factors.
  • 55. Figure 14.20 I Need Sleep!
  • 56. Manipulating Sleep Reveals an Underlying Structure
    • Total sleep deprivation compromises the immune system and leads to death.
    • The disease fatal familial insomnia is inherited—in midlife people stop sleeping and die 7-24 months after onset of the insomnia.
  • 57. Manipulating Sleep Reveals an Underlying Structure
    • Sleep recovery is the process of sleeping more than normally, after a period of deprivation.
    • Night 1—stage 4 sleep is increased, but stage 2 is decreased
    • Night 2—most recovery of REM sleep, which is more intense than normal with more rapid eye movements
  • 58. Figure 14.21 Sleep Recovery after 11 Days Awake
  • 59. What Are the Biological Functions of Sleep?
    • Four functions of sleep:
    • Energy conservation
    • Predator avoidance
    • Body restoration
    • Memory consolidation
  • 60. What Are the Biological Functions of Sleep?
    • Energy is conserved during sleep: muscular tension, heart rate, blood pressure, temperature and rate of respiration are reduced
    • Small animals sleep more than large ones, in correlation with their high normal metabolic rate.
  • 61. Figure 14.22 Sleep Helps Animals to Adapt an Ecological Niche
  • 62. What Are the Biological Functions of Sleep?
    • Sleep helps animals avoid predators—animals sleep during the part of the day when they are most vulnerable.
    • Sleep restores the body by replenishing metabolic requirements, such as proteins. Growth hormone is only released during SWS.
  • 63. What Are the Biological Functions of Sleep?
    • Explanations for memory consolidation and learning vary from passive to active:
    • Sleep during the interval between learning and recall may reduce interfering stimuli.
    • Memory typically decays and sleep may slow this down.
    • Or, sleep, especially REM, may actively contribute through processes that consolidate the learned material.
  • 64. Figure 14.23 A Nonsleeper
  • 65. At Least Four Interacting Neural Systems Underlie Sleep
    • Sleep is an active state mediated by:
    • A forebrain system, displays SWS
    • A brainstem system, activates the forebrain
    • A pontine system, triggers REM sleep
    • A hypothalamic system, affects the other three
  • 66. At Least Four Interacting Neural Systems Underlie Sleep
    • Transection experiments showed that different sleep systems originate in different parts of the brain.
    • Enc é phale isol é , or isolated brain , is made by an incision between the medulla and the spinal cord.
    • Animals showed signs of sleep and wakefulness, proving that the networks reside in the brain.
  • 67. At Least Four Interacting Neural Systems Underlie Sleep
    • Cerveau isol é , or isolated forebrain , is made by an incision in the midbrain.
    • The electrical activity in the forebrain showed constant SWS, but not REM—thus the forebrain alone can generate SWS.
  • 68. Figure 14.24 Brain Transections Reveal Sleep Mechanisms
  • 69. At Least Four Interacting Neural Systems Underlie Sleep
    • The constant SWS activity in the forebrain is generated by the basal forebrain .
    • Neurons in this region become active at sleep onset and release GABA.
    • GABA suppresses activity in the nearby tuberomamillary nucleus .
  • 70. At Least Four Interacting Neural Systems Underlie Sleep
    • Reduced activity in the tuberomamillary nucleus suppresses wakefulness.
    • General anesthetics make GABA A receptors in the tuberomamillary nucleus more sensitive to GABA and induce a SWS state.
  • 71. At Least Four Interacting Neural Systems Underlie Sleep
    • The reticular formation is able to activate the cortex.
    • Electrical stimulation of this area will wake up sleeping animals while lesions of this area promote sleep.
    • The forebrain and reticular formation seem to guide the brain between SWS and wakefulness.
  • 72. At Least Four Interacting Neural Systems Underlie Sleep
    • An area of the pons, near the locus coeruleus, is responsible for REM sleep.
    • Some neurons in this region are only active during REM sleep.
    • They inhibit motoneurons to keep them from firing, disabling the motor system during REM sleep.
  • 73. Figure 14.25 The Brainstem Reticular Formation
  • 74. Figure 14.26 Sleep Stage Postures
  • 75. At Least Four Interacting Neural Systems Underlie Sleep
    • The study of narcolepsy revealed the hypothalamic sleep center.
    • Narcolepsy sufferers:
    • Have frequent sleep attacks and excessive daytime sleepiness
    • Do not go through SWS before REM sleep
    • May show cataplexy—a sudden loss of muscle tone, leading to collapse
  • 76. At Least Four Interacting Neural Systems Underlie Sleep
    • Narcoleptic dogs have a mutant gene for a hypocretin receptor.
    • Hypocretin normally prevents the transition from wakefulness directly into REM sleep.
    • Interfering with hypocretin signaling leads to narcolepsy.
  • 77. Figure 14.27 Narcolepsy in Dogs
  • 78. At Least Four Interacting Neural Systems Underlie Sleep
    • Hypocretin neurons in the hypothalamus project to other brain centers: the basal forebrain, the reticular formation and the locus coeruleus.
    • Axons also go to the tuberomamillary nucleus, whose inhibition induces SWS.
    • The hypothalamic hypocretin sleep center may act as a switch, controlling wakefulness, SWS sleep or REM sleep.
  • 79. Figure 14.28 Neural Degeneration in Humans with Narcolepsy
  • 80. At Least Four Interacting Neural Systems Underlie Sleep
    • Sleep paralysis is the brief inability to move just before falling asleep, or just after waking up.
    • It may be caused by the pontine center continuing to signal for muscle relaxation, even when awake.
  • 81. Sleep Disorders Can Be Serious, Even Life-Threatening
    • Sleep disorders in children:
    • Night terrors and sleep enuresis (bed-wetting) are associated with SWS.
    • Somnambulism (sleepwalking) occurs during stages 3 and 4 SWS, and may persist into adulthood.
  • 82. Sleep Disorders Can Be Serious, Even Life-Threatening
    • REM behavior disorder (RBD) is characterized by organized behavior from an asleep person.
    • It usually begins after age 50 and may be followed by beginning symptoms of Parkinson’s disease.
    • This suggests damage in the brain motor systems.
  • 83. Sleep Disorders Can Be Serious, Even Life-Threatening
    • Sleep state misperception occurs when people report insomnia even when they were asleep.
    • Sleep-onset insomnia is a difficulty in falling asleep, and can be caused by situational factors, such as shift work or jet lag.
    • Sleep-maintenance insomnia is a difficulty in staying asleep and may be caused by drugs or neurological factors.
  • 84. Sleep Disorders Can Be Serious, Even Life-Threatening
    • In sleep apnea, breathing may stop or slow down—blood oxygen drops rapidly.
    • Muscles in the chest and diaphragm may relax too much or pacemaker respiratory neurons in the brain stem may not signal properly.
    • Sleep apnea may be accompanied by snoring.
  • 85. Sleep Disorders Can Be Serious, Even Life-Threatening
    • Each episode of sleep apnea arouses the person to restore breathing, but may result in daytime sleepiness.
    • Treatments include a removable tube in the throat or a CPAP (continuous positive airway pressure) machine, to prevent collapse of the airways.
  • 86. Figure 14.29 A Machine That Prevents Sleep Apnea
  • 87. Sleep Disorders Can Be Serious, Even Life-Threatening
    • Untreated sleep apnea can lead to cardiovascular disorders.
    • Sudden infant death syndrome (SIDS) is sleep apnea resulting from immature respiratory pacemaker systems or arousal mechanisms.
    • Putting babies to sleep on their backs can prevent suffocation due to apnea.
  • 88. Figure 14.30 Back to Sleep
  • 89. Sleep Disorders Can Be Serious, Even Life-Threatening
    • Sleeping pills are not perfect—most bind to GABA receptors throughout the brain. Continued use of sleeping pills:
    • Makes them ineffective
    • Produces marked changes in sleep patterns that persist even when not taking the drug
    • Can lead to drowsiness and memory gaps