PSYB64 Part 3

• Biological rhythms


  Repeating cycles that are regulated by internal biological clocks
• Zeitgebers


  • Internal cues that help set biological rhythms
• Circadian rhythm


  A 24 hour cycle
• Ultradian rhythm


  A cycle that occurs several times in a single day at 90 to 120 minute intervals
• Free running circadian rhythm


  A circadian rhythm that is not synchronised to environmental time cues
• Zeitgebers


  • Light
  • Physical activity
  • Feeding
  • Body temperature
  • Sleep related hormones
• Chronotypes


  Individual sleep patterns (larks vs night owls)
• Suprachiasmatic nucleus (SCN)


  The body's master internal clock, located in the hypothalamus
• ipRGCs


  Intrinsically photosensitive ganglion cells that provide input to the SCN
• The SCN is most active during the day and helps species distinguish whether it is night or day
• Melatonin release


  1. Levels are low during the day

  2. Levels begin to rise in the hours before sleep

  3. Melatonin release is suppressed by light
• Cortisol


  Hormone released by adrenal glands, levels are normally high early in the mornings
• Desynchronous brain activity


  Correlated with wakefulness and alertness
• Synchronous brain activity


  Related to deep stages of sleep
• Brain wave types


  • Mu waves
  • Alpha waves
  • Beta waves
  • Gamma waves
• NREM sleep stages


  • Stage 1: Alpha waves replaced by theta waves, heart rate and muscle tension decrease
  • Stage 2: More reductions in heart rate and muscle tension, sleep spindles and K-complexes appear
  • Stage 3: Very low body temperature, breathing, and heart rate, delta wave activity
• REM sleep


  Vivid dreaming, rapid eye movement, sympathetic nervous system activation, paralysis with small twitches
• Major brain structures for sleep and wakefulness

  • Basal forebrain
  • Brainstem
  • Ventral pathway
  • Dorsal pathway
  • Raphe nuclei
  • Default mode network
  • NREM sleep networks
  • REM sleep networks
• Neurotransmitters and their roles

  • High in wakefulness and REM: Acetylcholine, glutamate
  • High in wakefulness, lower in REM and NREM: Histamine
  • High in wakefulness, drop in NREM, very low in REM: Norepinephrine, serotonin
  • Builds up in wakefulness, drops in sleep: Adenosine
• Leading theory of why we evolved to sleep

  Sleeping keeps us safe, restores the body, and consolidates memories
• Shift maladaptation syndrome


  Excessive sleepiness at work but impaired sleep at home, resulting in health, personality, mood, and interpersonal problems
• Jet lag


  Fatigue, irritability and sleepiness resulting from travel across time zones
• Reflexive behaviours


  Inevitable and involuntary responses to stimuli, due to pre-wired neural connections
• Fixed action patterns


  Automatic and unconscious responses to the environment, often involving mating or parenting behaviour
• Types of learned behaviours

  • Non-associative learning (habituation, sensitization)
  • Associative learning (classical conditioning, operant conditioning)
  • Social learning
• Classical conditioning


  Organisms learn that stimuli act as signals that predict the occurrence of other important events
• Operant conditioning


  Organisms form connections between their behaviour and the consequences that impact whether they will do that behaviour again or not
• Habituation


  Organism reduces response to unchanging, harmless stimuli
• Sensitization


  The experience of one stimulus makes you more sensitive and heightens the response to other similar stimuli
• Operant conditioning


  Shares many neural systems with classical conditioning
• Extinction of operant responding

  1. Requires active engagement of prefrontal cortex to assess context

  2. Requires engagement of amygdala, hippocampus, thalamus, and nucleus accumbens
• Dopamine neurons


  • Play a key role in operant conditioning
  • Rapidly fire when a reward is unexpected or better than expected
  • Suppress firing when an expected reward does not occur or punishment occurs instead
• Habituation


  • Occurs when organism reduces response to unchanging, harmless stimuli
  • Example: Getting used to a nearby train after moving into a house
• Sensitization


  • When the experience of one stimulus makes you more sensitive and heightens the response to other similar stimuli
  • Example: Becoming scared of sudden movements after experiencing an earthquake
• • Social learning involves many of the same circuits as classical and operant conditioning
  • Can also occur in groups
  • Example: Bobo doll experiment
• Memory


  • Central to all cognitive functions
  • Has 3 stages: Encoding, Storage, Retrieval
• Sensory memory


  • Large capacity
  • Lasts up to 1-2 seconds
  • Stores information from our senses
  • We select what we want to attend to and the rest is forgotten
  • Example: Briefly storing images of paintings in an art gallery
• Short-term memory (working memory)


  • Can hold approximately 7 items for around 30 seconds
  • Combines: central executive, episodic buffer, visuospatial sketchpad, and phonological loop
  • Dorsolateral prefrontal cortex and ACC support the central executive and also play a part in object permanence
  • Small activation of ACC accompanies maintenance rehearsal
  • Large activation of ACC accompanies semantic rehearsal
  • Can be tested by Wisconsin Card Sorting Task
• Types of long-term memory

  • Declarative (semantic, episodic)
  • Non-declarative (procedural)
• Declarative memory


  • Contains basic knowledge of facts and languages
  • Semantic memory is widely distributed in the cortex
  • Episodic memory relates to personal experience
  • Temporal lobes are significantly involved
  • Patient H.M. had impairment due to removal of hippocampus, amygdala, and part of association cortex
  • Delayed nonmatching to sample task is a declarative memory task