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Memory and Amnesia

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Memory and Amnesia Nathan Spreng Cognitive Neuroscience: PSY393 August 2, 2005 Amnesia at the movies Remember Sammy Jankis? Memory Lecture Summary Memory Process and ... – PowerPoint PPT presentation

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Title: Memory and Amnesia


1
Memory and Amnesia
  • Nathan Spreng
  • Cognitive Neuroscience PSY393
  • August 2, 2005

2
Amnesia at the movies
3
Remember Sammy Jankis?
4
Memory Lecture Summary
  • Memory
  • Process and Definitions
  • Systems
  • Medial Temporal Lobe Classic Amnesia
  • Encoding Retrieval
  • Case studies
  • Frontal Lobes
  • Working Memory DLPFC
  • Working with Memory
  • Case study
  • Autobiographical Memory

5
Memory is...
  • A group of mechanisms or processes by which
    experience shapes us, changing our brain and
    behaviour
  • The product of learning

6
Memory involves...
  • Acquisition
  • Retention
  • Ability to retrieve
  • information
  • personal experiences
  • procedures (skills and habits).

7
Memory enables...
  • Adaptation to the environment
  • Improvement of our interactions with the outside
    world
  • Intergenerational transfer of knowledge

8
Short and Long Term Memory
  • Memory can be divided into
  • Time (seconds to minutes to years)
  • Contents (7 plus minus 2)
  • Systems by type of information

9
Sensory perception in sensory brain areas
Initial processing (association with previous
information) - Trace
Deeper processing Engram formation
Stable representation in central nervous system
Reproduction of previously stored information
Recollection
Re-encoding through retrieval initial trace
(engram) changes
10
Memory Systems
11
Memory Systems
  • Implicit Memory Memory without awareness
  • Skills, priming, etc (spared in amnesia)
  • Explicit Memory/Declarative Memory
  • Memory accompanied by an awareness of
    recollection. May be declared or verbally
    reported

12
Amnesia
  • Definition An abnormal mental state in which
    memory and learning are effected out of all
    proportion to other cognitive functions in an
    otherwise alert and responsive patient
  • Kopelman (2002)
  • Memory can be compromised in isolation from other
    cognitive abilities
  • Amnesia is selective, effecting certain
    capacities, showing that there are many systems
    of memory

13
Temporal Extent of Amnesia
  • Anterograde amnesia
  • Deficit in new learning
  • Inability to form new memories AFTER time of
    injury
  • Retrograde amnesia
  • impairment of memory of information PRIOR to
    onset of amnesia
  • temporal gradient, effecting recent gt remote

14
Temporal Extent of Amnesia
  • Ribots Law (1882) The progression of the
    destruction of memory follows a logical order.
    It begins with the most recent recollections,
    being rarely repeated, and having no permanent
    associations
  • Greater compromise of recent memory over remote

15
Temporal Extent of Amnesia
16
The case of H.M.
  • HM - surgery for intractable epilepsy.
  • Resection of hippocampus, parahippocampal gyrus,
    amygdala uncus.
  • HM could not form new memories (anterograde
    amnesia).
  • Retrograde amnesia (11 years)
  • Right HM vs. 66-yr old Control

Anterior
Posterior
(Corkin et al., 1997)
17
Etiology of Amnesia
  • Korsakoffs syndrome (Jimmy)
  • Herpes encephalitis (Clive)
  • Severe hypoxia
  • Vascular disorders
  • Head Injury (K.C.)
  • Dementia (J.S.)
  • Transient global amnesia (fugue state)

18
Amnesia
  • Inability to form new long term memories
  • Assessed with
  • Free recall (no info)
  • Cued recall (starting with c)
  • Recognition (target and lures used)
  • Savings in relearning (also impaired in amnesia)

19
Memory Systems
Impaired
Spared
20
Implicit Memory
  • Memory without awareness
  • Spared in classical amnesia
  • Priming Primary Sensory Cortex
  • Procedural Memory - Striate

21
Implicit Memory
  • Gollin Incomplete Pictures task
  • Repetition Priming
  • Bias to previous exposure

22
Implicit Memory
  • Eye movements to assess implicit memory
  • Top Initial exposure, eye movements over 3 items
  • Bottom 2nd exposure, eye movements over where
    one item would be

23
Implicit Memory
  • Procedural Memory
  • Improvement in performance without recollection
    of the material
  • Spared in amnesia

Mirror Reading Task
24
Declarative Memory
  • Semantic Memory Knowing
  • Knowledge of words and their meanings, objects,
    concepts and facts.
  • Episodic Memory Remembering
  • Re-experiencing of an event that occurred in the
    past including time and place of original
    encoding episodemental time travel.

25
The case of K.C.
  • TBI
  • Bilateral hippocampus frontal lobe damage
  • Severe RA and AA
  • No episodic memory
  • Intact semantic memory

26
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27
Memory Circuit
(Mayes, 2000)
28
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29
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30
Medial Temporal Lobe
  • Hippocampus as Convergence zone
  • Memories are not stored within the hippocampus
  • Hippocampus acts as an indexor and lays trace
    of memories.
  • Memories are stored in sensory cortex
  • Hippocampus has access to all sensory information
  • Relational Memory

31
Medial Temporal Lobe
  • Morris Water Maze
  • Hippocampal lesions
  • Deficits in learning and remembering spatial
    relations

32
Medial Temporal Lobe
  • Hippocampal Lesions Material specific memory
    disorder
  • Unilateral
  • Left verbal impairment
  • Right nonverbal impairment
  • Bilateral - Global impairment
  • fMRI Hippocampus Material dependent activity at
    encoding
  • Verbal - Left
  • Nonverbal - Right

33
Medial Temporal Lobe
  • Hippocampal activity predicts successful recall
  • During encoding
  • During retrieval (Nyberg, et al., 1996)
  • Subsequent Memory Effect

34
Medial Temporal Lobe
  • While memories are young, they depend upon an
    intact hippocampus
  • Are old episodic memories independent hippocampus
    once consolidated?

35
Medial Temporal Lobe
  • fMRI Robustness of hippocampal activity during
    retrieval related to vividness of memory, not age
    (Gilboa, 2003)
  • H.M. possesses some remote memories.
  • Are they episodic? Depends on measure
  • lack episodic content, semanticized
    (Steinvorth Corkin, submitted)

36
Medial Temporal Lobe
  • How does the hippocampus bind information?
  • LTP
  • Hebbs Law
  • Connectivity

(Rolls, 2000)
37
  • Same brain regions activated for perception and
    retrieval
  • Regions
  • fusiform gyrus (a)
  • superior temporal gyri (d)
  • Retrieval of pictures and sounds, respectively

(2004) Proc. Natl. Acad. Sci. USA 101, 5181
38
MTL Emotion
  • Emotionality enhances memory performance
  • Mediated by the Basolateral limbic circuit
  • Parahippocampus and perirhinal cortex connect
    with the amygdala
  • Orbitofrontal cortex involved in processing
    salience at encoding
  • Emotion enhances attention

39
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40
Want Slides? Please provide email address
Video NoT cue 17-27 minutes Video
Tulving/Milner Clive cue 6-18 minutes
41
Clive Wearing
  • R-handed
  • Above average IQ
  • Prominent Musician
  • Herpes Simplex Encephalitis
  • Bilateral temporal lobe degeneration LgtR
  • Dense Anterograde Amnesia

(Wilson Wearing, 1995)
42
Clive Wearing
43
Frontal Lobes
  • Tennessee Williams
  • Life is all memory except for the present moment
    that flies by so quickly that you can hardly
    catch it going by
  • WM moment
  • LTM past

44
Working Memory
  • Central Executive Attentional control of the
    slave systems
  • Visuo-spatial sketchpad
  • Phonological loop
  • Both derive and feed information to and from LTM
  • WM is a combination of maintenance and
    manipulation operations and works in close
    interaction with LTM

45
Basic WM paradigms
  • Delayed response
  • Delayed alternation
  • Object alternation
  • Go No-Go
  • Reversal
  • Delayed match to sample
  • Delayed non-match to sample
  • Recurring stimuli (recall most recent
    presentation)
  • Trial-unique stimuli (distinguish familiar from
    novel)

46
Component processes of WM
  • Mnemonic
  • Register (encode)
  • Store (maintain)
  • Rehearse
  • Non-Mnemonic
  • Control interference (inhibit)
  • Manipulate
  • Select (retrieve, prepare)
  • Respond (motor effector)
  • Domain-specific sensory systems (spatial, object)

47
Working Memory
  • Delayed Response Task
  • Access spatial information
  • Hold information on on-line during delay period
  • Initiate motor response
  • Delay tasks sensitive to principal suclus
  • Impaired with lesions
  • Evidence for delay-specific neurons

48
Working Memory
  • Shared working memory circuit in humans
  • BA9/46 (DLPFC)
  • Posterior Parietal
  • Left Hemisphere
  • Delayed response
  • Delayed alternation
  • Object alternation
  • Guide behavior in the absence of external cues

49
Functional neuroimaging (DEsposito et al., 2000
Fletcher Henson, 2001)
  • DLPFC
  • Encoding (supraspan)
  • Maintenance
  • Manipulation
  • Scanning
  • VLPFC
  • Maintenance
  • Rehearsal
  • Inhibit, select
  • Anterior PFC (Poles)
  • More complex manipulation

50
Frontal lobes and working with memory
  • Associative retrieval conscious recollection
    that are cue-driven
  • medial temporal lobes (MTL)
  • Strategic Retrieval problem solving approach to
    memory where
  • the frontal lobes work with memories
  • delivered through the medial temporal lobes and
    posterior neocortex

Video cue 35 minutes TRAIN
51
Frontal lobes and working with memory
  • Frontal-medial temporal interactions
  • encoding
  • retrieval

Simons Spires (2003)
52
Frontal lobes and working with memory
  • Meta memory judgments
  • Source amnesia
  • Dissociation between item and contextual
    information (details of study episode)
  • Judgment of recency (Milner, 1971)
  • Left-sided lesions affect verbal
  • Right-sided lesions affect verbal and visual
  • Temporal ordering (Milner, 1971)

53
Frontal lobes and working with memory
  • Confabulation
  • Defined as an honest lying
  • Requires retrieval, sequencing, output monitoring
  • Associative retrieval intact, strategic retrieval
    impaired
  • Source amnesia magnified and extended to include
    an entire lifetime of experience (Moscovitch,
    1989)

Schnider, 2003
54
Patient J.S. Frontotemporal dementia
R
R
L
L
R
(McKinnon, et al., in preparation)
55
The case of JS Confabulation
  • MK Can you tell me about Detroit again?
  • JS We were in this nice restaurant and a guy
    said I dont think you guys should go outside.
    Theres a sniper on the roof outside. He said I
    think you had better stay in here. Ive just
    called the cops. (laughter) He said theres a
    sniper on the roof. He said you guys had better
    stay in here.
  • MK Then what happened?
  • JS Well the cops came. The cops got the guy.
    And they said okay guys you can leave now. That
    was all the help and we went outside.

56
Autobiographical Memory
  • Memory of, or relating to, the self
  • Involves episodic memory (ie autonoetic
    awareness)
  • Semantic memory
  • Mental Time Travel

57
Autonoetic consciousness Wheeler, Stuss Tulving
(1996) Tulving (2002)
  • Awareness of the self as a continuous entity
    across time

"Remembrance is like a direct feeling its object
is suffused with warmth and intimacy to which no
object of mere conception ever attains." James
(1890) "It's essence lies in the subjective
feeling that the present experience is of an
earlier, similar one, and in the belief that the
self doing the experiencing now is the same self
that did it originally." Wheeler, Stuss,
Tulving (1997)
58
Ascendancy of personal re-experiencing over
childhood amnesia
Bruce et al., 2000
59
Mental Time Travel Past Future
Spreng Levine (in press)
60
Autobiographical memory
61
Autobiographical recollection Personal episodic
versus personal semantic
a) Anteromedial prefrontal cortex
b) Superior medial prefrontal cortex
c) Ventrolateral prefrontal cortex
d) Temporoparietal junction
e) Posterior cingulate/Precuneus
f) Thalamus (anterior nucleus)
62
Kopelman, 2002
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