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 HMd. nature of the cognitive process in memorye. memory is compartmentalized in the brainf. phenomenon of consolidation

phenomenon of consolidation

The time-limited function of medial temporal memory system: storage or retrieval?

Amnesiai. retrograde (backward-acting) amnesia

lost of memory for information learned before the amnesia inducing brain injuryii. 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 viewi. 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 memory2. 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

grammarii. perceptual learning

(a)Gollins partial picture task (b)Mirror reading

iii. Pavlovian conditioningiv. 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 PATIENTSGraf, 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 conditionimpaired 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 MEMORYDefinitions

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