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					MULTIPLE MEMORY SYSTEM IN HUMANS

QUESTIONS:
a. Who is HM and why is he so valuable to
memory research?
b. what memory capacities are spared?
c. how is the kind of memory lost in amnesia
best characterized?

IMPLICATION OF THE FINDINGS ON HM
d. nature of the cognitive process in memory
e. memory is compartmentalized in the brain
f. phenomenon of consolidation
phenomenon of consolidation
The time-limited function of medial temporal memory
system: storage or retrieval?

Amnesia
i. retrograde (backward-acting) amnesia
        lost of memory for information learned before
the amnesia inducing brain injury
ii. anterograde (forward-acting) amnesia
        lost of memory for information learned after the
amnesia-inducing brain injury
Retrograde amnesia can not be simply
    described as a retrieval deficit
i. memory acquired just prior to the amnesic
    episode can not be recovered.
ii. memory acquired well before the amnesic
    episode can be recovered
Medial temporal system is not repository of long term
memory

Current view
i. Medial temporal memory system initially binds
together the distributed sites in neocortex that
together represent the memory of a whole event.
ii. This low-capacity, fast system permits the
acquisition and storage, and for a period it provides a
basis for retrieving the full representation.
iii. At time passes, the burden of long-term memory
storage is assumed fully by neocortex.
The selective nature of the amnesic case

1. selective to memory
2. selective to particular domains of learning
and memory capacity

     a. Remember materials learned
remotely prior to his operation
     b. Immediate or short term memory
     c. Nondeclarative memory
“Nondeclarative”
i. acquisition of skills
     (1)Motor skills: Mirror drawing
     (2)Motor Skills: rotary-pursuit task
     (3)cognitive skills: Honoi puzzle, artificial
       grammar
ii. perceptual learning
     (a)Gollins partial picture task
     (b)Mirror reading
iii. Pavlovian conditioning
iv. priming
                      Priming

(1) initial presentation of a list of words, pictures,
(2) then subsequent reexposure to
       (a) fragments or
       (b) very brief presentation of the whole
item
(3) learning is measured by requesting subjects
to reproduce the whole item from a fragment
              (i) increased ability
              (ii) increased speed
word stem completion task (verbal repetition
priming)
(a) stimulus: MOTEL
(b) test: MOT______
(c) alternative: mother
(d) testing conditions
       (i) free recall
       (ii) word completion condition (to report
“the first word that come to mind” that complete
the word stem)

priming is not limited to verbal materials
  Common or fundamental properties of
   memory that is spared in amnesia
 NOT limited to
• i. general motors skills
• ii. simple forms of perceptual learning or
  simple tasks
• iii. types of learning that involve slow
  incremental improvement
• iv. particular category of learning materials
         Example of Characteristics of
           Declarative Memory and
           Nondeclarative Memory
• Daniel Schacter: explicit and implicit
  memory
• Endel Tulving: Episodic and semantic
  memory
Double dissociation and one-way
          dissociation
EXPERIMENTAL DISSOCIATIONS
A dissociation occurs when one variable is shown to affect one test
differently than another

COMPARISON BETWEEN NORMAL AND AMNESIC PATIENTS
Graf, Squire, and Mandler (1984)
Word-stem Completion Study
Words' three initial letters form the initial stem of several different words
(not included on the study list). E.g,
          motel - > mother, ...
          cyclone -> cycle, ...
Ss were presented with a list of such words to
study and were then tested in two different
conditions:

  cued-recall condition
    impaired performance by amnesic patients
  word completion condition
    intact performance by amnesic patients
                  Interpretations
cued-recall
   –    Ss are encouraged to compare each of the stems to the
        stored representation of whole words
   –    This requires representation of the relations among these
        arbitrarily associated words
   –    and required flexible manipulation of these representations to
        permit their comparison with each stems.
word completion
   –    through a facilitation of the word-identification process for
        previously presented words,
   –    expressed when (and only when) producing those words
        again.
   –    Not require that S be capable of judging that the words had
        been previously presented, or express a memory
        representation in any other way
COMPARISON BETWEEN DIFFERENT DAYS OF MEMORY
RETENTION
(experiment using normal subjects only)
Tulving, Schacter, and Stark (1982)

Phase I: Ss were asked to learn a list of words
Phase II: 1 hour's later
         word-fragment completion test or recognition test
Phase III: 7 days later
         same tests
Result:
   •Duration of retention interval affected the direct and indirect
   measures differently:
   •Long retention interval resulted in worse performance on the
   direct test, but no effect on indirect test
DECLARATIVE MEMORY: EPISODIC MEMORY AND
SEMANTIC MEMORY
Definitions

   Episodic memory, experience of remembering
               The explicit recollection of incidents that
       occurred at a particular time and place in one's personal
       past

   Semantic memory, experience of knowing
                 General knowledge of facts and concepts that
      is not linked to any particular time and place
Dissociation between Episodic memory and Semantic
memory

   Patient K.C.
        •Damage to medial temporal and frontal regions
        •Unable to recollect a single episode from any time in
        his entire life yet possessed extensive semantic
        knowledge of facts and concepts

   A patient
       •Damage to anterior sectors of the temporal lobe
       •Could remember specific past episode, but had great
       difficulty understanding the meaning of common words
       and had lost knowledge of historical events

   Elderly patients with syndrome of semantic dementia
       •Reduced metabolic activity of and structural atrophy in
       the anterior and lateral regions of the temporal lobe.
       •Poor knowledge of the properties of specific objects,
       yet intact episodic memory

				
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posted:1/15/2011
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