Learning and Memory

1
Learning and Memory

• Learning process of acquiring new information.
  The outcome of learning is
• Memory persistence of information that can be
  revealed at at later time.

2
Processes of Learning and Memory

• Encoding processing of new information
• Acquisition sensory registration and analysis
• Consolidation strengthening of representation
  over time
• Storage creation and maintenance of permanent
  record
• Retrieval use of stored information

3
Taxonomy of Memory

• Sensory short duration persistence of
  information
• Short-term medium duration persistence of
  information
• Long-term long duration persistence of
  information

4
Properties of Memory

• Sensory short duration persistence of
  information
• High capacity
• Iconic visual, lt 1 s duration
• Sperling's partial report studies

5
Properties of Memory

• Sensory short duration persistence of
  information
• High capacity
• Iconic visual, lt 1 s duration
• Echoic auditory, about 10 s duration
• Sams et al. (1993) - mismatch field

6
Properties of Memory

• Sensory
• Short-term
• Limited-capacity
• G. Miller - Magic number 7 /- 2
• Chunking
• Maintenance by rehearsal
• Loss via decay Petersen and Petersen (1959)

7
Properties of Memory

• Sensory
• Short-term
• Limited-capacity
• Maintenance by rehearsal
• Loss via decay
• Serial position effect
• Primacy LTM, eliminated by preventing storage
  (increased pace)
• Recency STM, eliminated by preventing rehearsal
  (distractor task at end of list)

8
Properties of Memory

• Sensory
• Short-term
• Limited-capacity
• Maintenance by rehearsal
• Models of STM
• "Modal" model (e.g., Atkinson and Schiffrin
  1968))

9
Properties of Memory

• Sensory
• Short-term
• Limited-capacity
• Maintenance by rehearsal
• Models of STM
• "Modal" model (e.g., Atkinson and Schiffrin
  1968))
• BUT, patients with damage near left supramarginal
  gryus have impaired digit span and can still form
  long term memories

10
Properties of Memory

• Sensory
• Short-term
• Limited-capacity
• Maintenance by rehearsal
• Models of STM
• "Modal" model (e.g., Atkinson and Schiffrin
  1968))
• Levels of processing (Craik and Lockhart, 1972)
• Shallow superficial, poor LTM
• Deep based on meaning, good LTM

11
Properties of Memory

• Sensory
• Short-term
• Limited-capacity
• Maintenance by rehearsal
• Models of STM
• "Modal" model (e.g., Atkinson and Schiffrin,
  1968)
• Levels of processing (Craik and Lockhart, 1972)
• Working memory (Baddeley, 1995)

12
Properties of Memory

• Sensory
• Short-term
• Limited-capacity
• Maintenance by rehearsal
• Models of STM
• "Modal" model (e.g., Atkinson and Schiffrin,
  1968)
• Levels of processing (Craik and Lockhart, 1972)
• Working memory (Baddeley, 1995)
• Damage in LH to Area 40 affects acoustical
  processing
• Damage in LH to Area 44 affects verbal rehearsal
• Damage to LH or RH parieto-occipital areas
  affects visuospatial working memory, but more so
  in RH

13
Properties of Memory

• Sensory
• Short-term
• Long-term
• Virtually unlimited capacity
• Loss via interference
• Modular

14
Properties of Memory

• Long-term
• Subdivisions
• Declarative explicit, conscious, personal and
  world knowledge
• Episodic
• Semantic
• Nondeclarative implicit, below conscious
  awareness, skill-based
• Procedural
• Perceptual representation system
• Associative
• Nonassociative

15
Patient Studies of Amnesia

• Amnesic patients have lost some aspect of memory
  function after neurosurgery, disease, head
  injury, etc.
• Memory processes (encoding, storage, retrieval)
  and subdivisions of memory systems (STM/WM, LTM,
  declarative, nondeclarative) supported by patient
  data
• Region of brain insult key to localization and
  differentiation of memory functions

16
Patient Studies of Amnesia

• Types of amnesia
• Illustration following ECT
• Anterograde loss of memory after incident
• Retrograde loss of memory preceding incident

17
Patient Studies of Amnesia

• Data supporting differentiation of STM / WM from
  LTM
• Patient EE
• Patient HM
• Patient RB

18
Patient Studies of Amnesia

• Lesion location
• Patient EE
• Removal of tumor in region of left angular gyrus,
  inferior parietal and posterior-superior temporal
  cortex

19
Patient Studies of Amnesia

• Lesion location
• Patient EE
• Patient HM
• Bilateral medial temporal lobectomy to relieve
  epilepsy

20
Patient Studies of Amnesia

• Lesion location
• Patient EE
• Patient HM
• Patient RB
• Bilateral ischemia localized to hippocampus
  during surgery

21
Patient Studies of Amnesia

• Symptomatology
• Patient EE
• Failure of short-term/working memory
  (visuospatial sketchpad?) assessed by Token Test
• Intact LTM

22
Patient Studies of Amnesia

• Symptomatology
• Patient EE
• Patients HM and RB
• Anterograde and isolated retrograde amnesia
• Normal STM (digit span)
• Failure of LTM

23
Patient Studies of Amnesia

• Summary from Patients EE, HM and RB
• Double dissociation of STM/WM and LTM
• Patients HM and RB provide evidence that the
  hippocampus is necessary at encoding stage for
  consolidation of declarative memories into LTM
• Hippocampus is not location for LTM storage
  (sensory and association neocortex?)
• Hippocampus is not involved in LTM retrieval
  (anterior and lateral temporal cortex?)
• BUT hippocampus not the only structure involved
  in formation of declarative memories

24
Patient Studies of Amnesia

• Diencephalic Amnesia
• Korsakoff's Syndrome
• Anterograde and retrograde amnesia similar to HM
  and RB in alcoholics
• Vitamin deficiencies that damage dorsomedial
  nucleus of thalamus and mammary bodies, but not
  medial temporal lobe

25
Patient Studies of Amnesia

• Encoding in Amnesia
• Amnesics can learn
• Information that can be learned supports distinct
  memory systems
• Often patients like HM can acquire some new
  semantic, but not episodic, information (loss of
  source memory)

26
Patient Studies of Amnesia

• Encoding in Amnesia
• Patient KC
• Severe head trauma following motorcycle accident
• Medial temporal, frontal, parietal and occiptal
  damage greater in LH than RH
• Normal IQ and STM (digit span)
• Severe anterograde and retrograde amnesia
  including loss of all episodic memory
• Retained old and could acquire new semantic
  memories

27
Patient Studies of Amnesia

• Encoding in Amnesia
• Learning nondeclarative information
• Procedural learning
• Serial reaction time task

28
Patient Studies of Amnesia

• Encoding in Amnesia
• Learning nondeclarative information
• Procedural learning
• Serial reaction time task
• Can be learned by patients like HM and
  Korsakoff's patients without episodic memory
• Learned poorly by patients with basal ganglia
  disorders (like Parkinson's)

29
Patient Studies of Amnesia

• Encoding in Amnesia
• Learning nondeclarative information
• Priming - improvement in identifying or
  processing a stimulus after observing it
• Perceptual representation system
• Word fragment completion test

30
Patient Studies of Amnesia

• Encoding in Amnesia
• Learning nondeclarative information
• Perceptual representation system
• Word fragment completion test
• Measure of implicit learning
• Performance not affected by depth of processing
  of list like explicit recognition task
• Performance declines across days instead of hours
  for explicit recognition task
• Perceptual phenomenon performance reduced when
  list presented auditorially

31
Patient Studies of Amnesia

• Encoding in Amnesia
• Learning nondeclarative information
• Perceptual representation system
• Word fragment completion test
• Impossible figures test

32
Patient Studies of Amnesia

• Encoding in Amnesia
• Learning nondeclarative information
• Perceptual representation system
• Word fragment completion test
• Impossible figures test
• Priming occurs for possible figures when deciding
  whether figure is possible

33
Patient Studies of Amnesia

• Encoding in Amnesia
• Learning nondeclarative information
• Perceptual representation system
• Double dissociation for PRS
• Patient KC
• Shows word-priming but no episodic memory
• Patient MS
• Removal of area 18 19 of RH to treat epilepsy
• Normal WAIS IQ and memory
• No word priming

34
Neuroimaging Studies

• Declarative Memory
• HERA Model Hemispheric encoding/retrieval
  asymmetry (Tulving et al., 1994)
• Encoding involves LH more than RH
• Retrieval involves RH more than LH

35
Neuroimaging Studies

• Declarative Memory
• Criticisms of HERA Model (Miller et al., 2002)
• Most studies use word stimuli
• Many use poorly controlled stimulus materials
• Both hemispheres can encode and retrieve, BUT are
  specific to material
• LH for words
• RH for faces
• Intra-hemisphere connections given preference
  over inter-hemisphere connections

36
Neuroimaging Studies

• Nondeclarative Memory
• Procedural memory (Grafton at al., 1995)
• Implicit motor learning involves motor cortex,
  supplementary motor area, putamen, basal ganglia,
  prefrontal and parietal cortex

37
Neuroimaging Studies

• Nondeclarative Memory
• Procedural memory (Grafton at al., 1995)
• Perceptual priming (Schacter et al., 1996)
• rCBF reduction in Brodmann area 19