BIOMED SCIE Lecture 20 sleep, emotion

• Why we sleep


  To sustaining normal levels of cognitive skills e.g. speech, memory and innovative and flexible thinking. Sleep plays an important part in brain "health" and plasticity (especially development)
• Lack of sleep


  Brain function is disrupted, leading to grumpiness, grogginess, irritability, forgetfulness, shortened attention span, and severely affected language, memory, planning and sense of time
• Sleep

  • An "active" state, with distinct EEG patterns that correlate with sleep stage and type
• Sleep requirement

  Varies from person to person, with an average of 7.75 hours
• Animal sleep times


  • Python: 18 hours
  • Tiger: 15.8 hours
  • Cat: 12.1 hours
  • Chimpanzee: 9.7 hours
  • Sheep: 3.8 hours
  • African Elephant: 3.3 hours
  • Giraffe: 1.9 hours
• Arousal and sleep


  • Controlled by the brainstem and cerebrum, with the reticular formation regulating the amount and type of information reaching the cerebral cortex
• Cyclical stages of sleep

  1. 90-110 minute cycles of non-REM and REM sleep

  2. Non-REM sleep stages: 1) Half awake/half asleep, Light sleep 2) aprox 20 minutes. Breathing pattern and heart rate start to slow down. 3) Deep sleep with delta waves, 4) Rhythmic breathing and limited muscle activity

  3. REM sleep: Brain very active, eyes dart around, breathing and blood pressure rise, body paralyzed. three to five REM occurrences a night, most dreams occur
• Electroencephalogram (EEG) and electrocorticogram (ECoG)


  Electrical recordings from the brain surface (electrocorticogram) and (electrocorticogram )scalp that reflect oscillations in thalamocortical circuits
• Discovery of the electroencephalogram in 1875 by Caton and 1929 by Berger
• Biological clock regulation


  Circadian rhythms, including sleep-wake cycles, are controlled by a biological clock mechanism in the suprachiasmatic nucleus (SCN) of the hypothalamus
• Melatonin levels


  Low during daylight, rise at night, peak between 11pm and 3am, and can adjust to environmental changes
• Suprachiasmatic nucleus (SCN)


  The site of the internal biological clock, with many intrinsic properties cycling including cortisol and body temperature. Melatonin binding inhibits neuron activity
• Emotion


  • Generation and experience involve the limbic system, including the amygdala, hippocampus, and parts of the thalamus
• Depression


  A state of low mood and aversion to activity that can affect a person's thoughts, behaviour, feelings and sense of well-being
• Depression treatmentsand disorders


  • Lifestyle changes
  • DISORDERS:
  • Selective serotonin reuptake inhibitors (SSRIs)
  • Serotonin-norepinephrine reuptake inhibitors (SNRIs)
  • Norepinephrine-dopamine reuptake inhibitors (NDRIs)
  • Tricyclic antidepressants
  • Monoamine oxidase inhibitors (MAOIs)
• melatonin


  Hormone that is naturally produced by the pineal gland• Is made predominantly at night• Conveys information to various parts of the body• Expressed rhythmically throughout the day
• How Melatonin Works


  • Melatonin levels cycle in our bodies• Low levels during daylight, rise during night time• Peak levels between 11pm and 3am

  • Levels continue to cycle in constant darkness• Can slowly adjust to environmental changes
• The structure most important to the storage of emotion in the memory is the amygdala, a mass of nuclei near

  the base of the cerebrum
• Generation and experience of emotion also require interaction between the limbic system and sensory areas of the cerebrum
• Amygdala, hippocampus, and parts of the thalamus= limbic system
• limbic system also functions in motivation, olfaction, behavior, andmemory
• Melatonin binding scn inhibits neuron activity
• The hormone melatonin is released by the pineal gland and plays a role in bird and mammal sleep cycles• Melatonin is used to treat jet lag