Memory

• Exam 2 average = 88%
• Neurological disease


  Pairs pick a disease
• Lecture 9
• Chapter 24
• Learning and memory


  Lifelong brain adaptation to environment
• Types of Memory


  • Learning: acquisition of new information
  • Memory: retention of learned information

  
• Declarative memory (explicit)


  Facts and events

  
• Nondeclarative memory (implicit)


  Procedural memory — motor skills, habits

  
• Nondeclarative memory


  • Rubix cube
• Types of Declarative and Nondeclarative Memory


  • Memory for skills, habits and behaviors - accessed for conscious recollection, easy to form, easy to forget (implicit memory)
  • Memory for facts and events - accessed for conscious recollection (explicit memory)

  
• Medial hippocampus


  Underneath
• Habituation


  'Learn' to ignore repetitive, irrelevant information
• Sensitization


  'Learn' to intensify response to all stimuli, even ones that previously evoked little response
• Nonassociative learning


  Change in behavioral response that occurs over time in response to a single type of stimulus
• Procedural Memory


  Type of Nondeclarative Memory, involves learning a motor response (procedure) in reaction to sensory input

  
• Procedural Memory


  • Two types: Nonassociative learning, Associative learning

  
• Striatum


  Caudate nucleus + putamen, key location in the motor loop, input from frontal and parietal cortex, output to thalamic nuclei and cortical areas involved in movement
• Lesions in striatum


  Disrupt procedural memory (habit learning) but not declarative memory

  
• Standard radial arm maze performance (declarative memory)

  Depends on hippocampus
• Modified radial arm maze performance (procedural memory)

  Depends on striatum

  
• Lights could be turned on or off at any time, optimal performance -> animal returns to retrieve food from lit arms as long as they were lit, and avoid arms that were never lit
• Procedural memory -> because of the consistent association between the presence of food and the illuminated lights, rat did not have to remember which arms it had already explored; it simply had to form a habit based on the association of the light with food
• Role of the striatum in habit learning and procedural memory

  
• Effects of selective brain lesions on memory -> comparable in rodents and primates

  
• In monkeys, striatum damage -> effects on performance memory (procedural memory) but not declarative memory

  
• Studies of patients with amnesia and Parkinson's disease (degeneration of the substantia nigra inputs to the striatum) - task: four cue cards presented in various combinations associated with the icons indicating sun or rain, based on repeated exposure to the combinations, patients had to learn to predict sun or rain by inferring the associations

  
• Associative learning


  Behavior is altered by the formation of associations between events (in contrast to a changed response to a single stimulus in non-associative learning)
• Classical conditioning (Pavlov)


  Pairing of unconditional stimulus with conditional stimulus
• Instrumental conditioning (Thorndike) aka Operant conditioning


  Associate a response with a meaningful stimulus
• Instrumental conditioning


  • A rat learning to associate a behavior with reward

  
• In classical conditioning, individual learns that one stimulus (Conditioned Stimulus) predicts another stimulus (Unconditioned Stimulus)
• In associative conditioning, individual learns that a particular behavior is associated with a particular consequence (motivation plays big role)
• Working memory


  Temporary storage, lasting seconds
• Short-term memory


  Temporary (hours), vulnerable to disruption
• Long-term memory


  Recall days, months, or years after the memory formed

  
• Theory of memory consolidation

  Hippocampus
• Amnesia


  Loss of memory and/or ability to learn

  
• Causes of amnesia


  • Concussion
  • Chronic alcoholism
  • Encephalitis
  • Brain tumor
  • Stroke
  • Psychological trauma
• Types of amnesia


  • Limited amnesia (common) — caused by trauma
  • Dissociated amnesia: no other cognitive deficits (rare)
  • Retrograde amnesia: memory loss for things prior to brain trauma
  • Anterograde amnesia: inability to form new memories after brain trauma

  
• We pay attention to small fraction of sensory information, some sensory information held briefly in working memory, small capacity, mostly discarded, some may be converted to long-term memory