Transcript Visual imagery deficits, impaired strategic retrieval, or memory loss

KC: The Role of Visual
Imagery Deficits within
Autobiographical Memory
Presented by : Juliana Peters
Rosenbaum, R.S., McKinnon, M.C., Levine, B., & Moscovitch, M.
(2004). Visual imagery deficits, impaired strategic retrieval, or
memory loss: disentangling the nature of an amnesic person’s
autobiographical memory deficit. Neuropsychologia, 42(12), 16191635.
• This puzzling problem arises when we ask, "Who is the I
that knows the bodily me, who has an image of myself
and a sense of identity over time, who knows that I
have propriate strivings?" I know all these things, and
what is more, I know that I know them. But who is it
who has this perspectival grasp? …It is much easier to
feel the self than to define the self.
-Gordon Allport
KC
• 50-year-old, right-handed man
• 15 years of education
• Suffered irreversible amnesia from
traumatic brain injury caused during a
motorcycle accident in 1981.
Damage
• Complete devastation
to right hippocampus
• Atrophy to right
parahippocampal
gyrus. Also in
mammillary bodies, the
septal area, and the
fornices.
Damage cont.
• Lesion in left occipital-temporal cortex,
and slightly in retrosplenial cortex;
lesions in medial occipital-temporalparietal, and left
frontal-parietal regions.
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Memory Impairment
• Severe Anterograde and Retrograde Amnesia
for autobiographical memory.
• Inability to place images within a temporalspatial context.
• Impairment seen on standardized tests of
memory.
– WASI: IQ of 99 (2003 assessment)
– WMS-R: 5th percentile on logical memory
– Autobiographical Memory Interview
Sustained Memory Abilities
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Semantic Memory
World Knowledge Remained
Schematic Cognitive Map
Executive Function Tests
– WASI similarities and matrix reasoning subtests
• Abstract Reasoning
• Concept Formation/Mental Flexibility
– Wisconsin Card Sorting test/Concept Generation
Test
Rosenbaum et al.’s Tests
• Main purpose: to see if K.C.’s memory loss
was due to malfunctioning of posterior
neocortex or to malfunctioning of frontal
neocortex.
• Experiment One: Visual imagery of object
identity and spatial location
– Wanted to see if visual imagery loss was at all an
important aspect of K.C.’s inability to recall his
personal past.
– Tested K.C.’s ability to segment, combine and
rotate mental images
– Tests included:
• Imagery for Object Size
• Imagery of Object Color
• Mental Clock Test
• Recreated Images
Experiment One Findings
• K.C. maintains functional imagery system.
– Was able to make accurate judgements of size,
shape, and spatial relations of tested objects.
– Showed ability to dismantle, rotate, and
reorganize visual representations
• Shows that the imagery system is “necessary
but…not sufficient for autobiographical
memory retrieval.”
Experiment Two:
Autobiographical Interview
• Wanted to distinguish if deficit was result of
problems in memory storage or shows deficit
in executive functioning to retreive details.
• Tested KC through Autobiographical Interview
(Moscovitch et al.& Levine et al.)
– Categorized retrievals as episodic or non-episodic.
- Categorized as internal or external
- Free Recall versus Specific Probe
Experiment 2 Findings
• The Autobiographical Interview
reinstated that K.C. had severe
retrograde amnesia for internal details.
– Unable to retrieve a single memory through
free recall.
– Specific Cue Retrieval provided only a
slight improvement for details
• Information provided lacked significant richness
Findings Suggest?
• As stated by Nadel and Moscovitch (1997),
the hippocampus plays a major role in the
retreival of autobiographical memories
throughout the life.
– Role of the hippocampal-neocortical interactions
• These studies do suggest that degeneration
of the neocortex and damage to the
hippocamal area are not the sole areas
responsible for the severe anterograde
amnesia
Future Research
• Scores from cued recall may be misleading due to
previous exposure.
– Future research needed to see the defining role of cued
recall on autobiographical memory retrieval.
• More research needed in recognition of past events.
– Does not depend on strategic search and just the
identification of a particular event
• Rosenbaum, although found that no relationship
between visual imagery deficits and memory loss, he
suggests that future research focus on other types of
neocortically mediated functions and their effects on
amnesia.