Post on 23-Feb-2016
description
Re-examining episodic amnesia with patient and fMRI studies
Jenny RabinNeuropsychology Rounds
September 9, 2013
What is Amnesia?
Impaired Abilities
• Episodic memory (EM)
Spared Abilities
• General intelligence
• Semantic memory
• Procedural memory
• Working memory
• Attention
Amnesia
Amnesia• For a long time it was thought that amnesia results in an
isolated deficit in EM
• However, there is growing evidence that other abilities may be impaired in amnesia
• E.g., Future thinking
– Early support came from conversations Endel Tulving had with K.C. (Tulving, 1985)
– Systematically replicated in other amnesic cases (Andelman et al., 2010; Kwan et al, 2010; Race et al., 2011)
EM and Future Thinking
Remembering Future Thinking
• Both abilities supported by a common core network
Addis et al., 2007, Neuropsychologia
EM and Future Thinking
Remembering Future Thinking
• Both abilities supported by a common core network• EM and the hippocampus contribute to imagining
the future– draw on details from past experiences to imagine future
eventsAddis et al., 2007, Neuropsychologia
Are there other abilities impaired in amnesia?
Theory of Mind (ToM)
• The ability to infer other people’s thoughts, feelings, beliefs, desires, and intentions (Premack & Woodruff, 1978)
• Recognize that other people can have different mental states from our own
• Use ToM automatically and effortlessly
Theory of Mind (ToM)
• How do we do infer others’ mental states?
• We rely on our own past experiences to simulate another person’s mental state (Buckner & Carroll, 2007; Gallagher & Frith, 2003; Spreng & Mar, 2012)
EM and ToM• There is evidence supporting the idea that ToM may rely
on EM
– Both abilities emerge around the same time during development (Perner & Ruffman, 1995)
– Impaired together in several patient populations (Corcorran & Frith, 2003; Dimaggio et al., 2012)
– Supported by a common set of brain regions that includes the hippocampus (Buckner & Carroll, 2007)
EM, Future Thinking, and ToM EM Future Thinking ToM
Addis et al., 2007 Saxe & Kanwisher, 2003
Buckner & Carroll, 2007
EM, Future Thinking, and ToM
Schacter, Addis & Buckner, 2008, Nat. Neurosci.
Outline
Study 1: Is ToM impaired in amnesia?
Study 2: What are the unique neural correlates of EM and ToM?
Study 3 and 4: Are there certain conditions under which ToM depends on EM?
Outline
Study 1: Is ToM impaired in amnesia?
Study 2: What are the unique neural correlates of EM and ToM?
Study 3 and 4: Are there certain conditions under which ToM depends on EM?
Study 1• Evidence that a core network of regions supports
EM, future thinking, and ToM (Buckner & Carroll, Spreng et al., 2009)
• Draw on past experiences to imagine the future and to simulate other people’s mental states
• Amnesic people have difficulty imagining the future (Andelman et al., 2010; Kwan et al, 2010; Race et al., 2011)
• Do amnesic people also have difficulty with ToM?
Study 1
• Participants:
– H.C., an individual with amnesia
– A group of demographically matched controls
Rabin et al., 2012, Neuropsychologia, see also Rosenbaum et al., 2007, Science
Patient H.C.• 20-year old woman
• Hypoxia one week after birth
• 30 - 50% bilateral hippocampal volume loss (Olsen et al., 2013)
• Therefore, she never developed normal episodic memory (Rosenbaum et al., 2011)
• Graduated from a mainstream high school and completed one year of technical college
Patient H.C. cont.
ToM Tests
• Tested H.C. and controls on a battery of ToM tests
• Same ToM tests that have been shown to activate the core network of regions involved in EM (Buckner & Carroll, 2007; Spreng et al., 2009)
• ToM tests that are sensitive to ToM impairment in a variety of patient groups (Gregory et al., 2002; Stone et al., 1998; Stone et al., 2003; Stuss et al., 2001)
Rabin et al., 2012, Neuropsychologia, see also Rosenbaum et al., 2007, Science
Mind in the Eyes Test
Hateful Jealous
Arrogant Panicked
Rabin et al., 2012, Neuropsychologia, see also Rosenbaum et al., 2007, Science
Mind in the Eyes Test
Hateful Jealous
Arrogant Panicked
Rabin et al., 2012, Neuropsychologia, see also Rosenbaum et al., 2007, Science
Faux Pas TaskJill had just moved into a new apartment. Jill went shopping and bought some new curtains for her bedroom. When she finished decorating the apartment, her best friend, Lisa, comes over. Jill gives her a tour of the apartment and asks, "How do you like my bedroom?" "Those curtains are horrible," Lisa replies. "I hope you're going to get some new ones!" Did anyone say something they shouldn't have said or something awkward?
If yes, ask:Who said something they shouldn't have said or something awkward?Why shouldn't he/she have said it or why was it awkward?Why did they say it?
Study 1: Results & Discussion
• H.C. performed at the same level as controls on all ToM tests
• Suggests that EM is not necessary for ToM, at least as measured by standard tests
• H.C. may be relying on her intact semantic knowledge to perform these tasks
Rabin et al., 2012, Neuropsychologia, see also Rosenbaum et al., 2007, Science
Study 1: Results & Discussion cont.
• Activation of a particular region during a task does not necessarily indicate that the region is necessary for that task
• Activation of the hippocampus during ToM, does not necessarily mean that the hippocampus is necessary for ToM
Outline
Study 1: Is ToM impaired in amnesia?
Study 2: What are the unique neural correlates of EM and ToM?
Study 3 and 4: Are there certain conditions under which ToM depends on EM?
Study 2• Evidence of a shared brain network underlying EM
and ToM based on independent fMRI studies (Buckner & Carroll, 2007; Spreng et al., 2009)
• Objective: To investigate EM and ToM in the same study using the same participants– Goal 1: Replicate the common pattern of activity observed
across studies– Goal 2: Are there differences in activation?
• Naturalistic paradigm using closely matched conditions
Study 2: Details
Participants:
• 18 healthy, middle aged adults (9 males; 9 females)
• Mean age = 57.2 years; SD = 8.0 years;
Family Photos Paradigm
Rabin et al., 2010, JOCN
Family Photos Paradigm
Rabin et al., 2010, JOCN
EM ToM
Participant Unfamiliar people
Family Photos Paradigm
Rabin et al., 2010, JOCN
EM ToM
Participant Unfamiliar people
Family Photos Paradigm
Rabin et al., 2010, JOCN
EM ToM
Participant Unfamiliar people
Recall each event in as much detail as possible and focus on what you were thinking and feeling at the time.
Create a novel event and focus on what one person in the photo was thinking and feeling at the time.
Task
Button Press
20 sec
Rabin et al., 2010, JOCN
Task
Button Press
Elaboration PhaseConstruction Phase
20 sec
Rabin et al., 2010, JOCN
Post Scan Interview• Viewed the same photos they saw in the
scanner
• Rate the vividness of each EM and ToM event they generated in the scanner
vague vivid
0 1 2 3 4 5 6
Rabin et al., 2010, JOCN
Post Scan Interview• Viewed the same photos they saw in the
scanner
• Rate the vividness of each EM and ToM event they generated in the scanner
vague vivid
0 1 2 3 4 5 6
Rabin et al., 2010, JOCN
Common Areas of Activation
EM
ToM
Rabin et al., 2010, JOCN
EM
ToM
Base
Base
Common Areas of Activation
EM
ToM
Rabin et al., 2010, JOCN
EM
ToM
Base
Base
Common Areas of Activation
EM
ToM
Rabin et al., 2010, JOCN
EM
ToM
Base
Base
Common Areas of Activation
EM
ToM
Rabin et al., 2010, JOCN
EM
ToM
Base
Base
Differences in Activation
• All regions activated were engaged to a greater extent during EM vs. ToM
Construction Phase
Rabin et al., 2010, JOCN
Differences in Activation
• Midline regions showed greater activity during EM– Self-related processes (Craik et al., 2002)
– Realness of events (Summerfield et al., 2009)
• Lateral regions showed greater activity during ToM– Involved in semantic memory (Martin & Chao, 2001)
Rabin et al., 2010, JOCN
EM
ToM
Elaboration Phase
Differences in Activation
• Midline regions showed greater activity during EM– Self-related processes (Craik et al., 2002)
– Realness of events (Summerfield et al., 2009)
• Lateral regions showed greater activity during ToM– Involved in semantic memory (Martin & Chao, 2001)
Rabin et al., 2010, JOCN
EM
ToM
Elaboration Phase
Differences in Activation
• Midline regions showed greater activity during EM– Self-related processes (Craik et al., 2002)
– Realness of events (Summerfield et al., 2009)
• Lateral regions showed greater activity during ToM– Involved in semantic memory (Martin & Chao, 2001)
Rabin et al., 2010, JOCN
EM
ToM
Elaboration Phase
Differences in Activation
• Midline regions showed greater activity during EM– Self-related processes (Craik et al., 2002)
– Realness of events (Summerfield et al., 2009)
• Lateral regions showed greater activity during ToM– Involved in semantic memory (Martin & Chao, 2001)
Rabin et al., 2010, JOCN
EM
ToM
Elaboration Phase
Differences in Activation
• Midline regions showed greater activity during EM– Self-related processes (Craik et al., 2002)
– Realness of events (Summerfield et al., 2009)
• Lateral regions showed greater activity during ToM– TPJ is a key region involved in ToM (Saxe et al., 2006)
– VLPFC and lateral temporal cortex; regions known to support semantic memory (Martin & Chao, 2001)
Rabin et al., 2010, JOCN
EM
ToM
Elaboration Phase
Differences in Activation
• Midline regions showed greater activity during EM– Self-related processes (Craik et al., 2002)
– Realness of events (Summerfield et al., 2009)
• Lateral regions showed greater activity during ToM– TPJ is a key region involved in ToM (Saxe et al., 2006)
– VLPFC and lateral temporal cortex; regions known to support semantic memory (Martin & Chao, 2001)
Rabin et al., 2010, JOCN
EM
ToM
Elaboration Phase
Differences in Activation
• Midline regions showed greater activity during EM– Self-related processes (Craik et al., 2002)
– Realness of events (Summerfield et al., 2009)
• Lateral regions showed greater activity during ToM– TPJ is a key region involved in ToM (Saxe et al., 2006)
– VLPFC and lateral temporal cortex; regions known to support semantic memory (Martin & Chao, 2001)
Rabin et al., 2010, JOCN
EM
ToM
Elaboration Phase
Study 2: Discussion• Replicated common network supporting EM and ToM
– Healthy people may rely on EM during ToM
• For the first time showed differences between the two
• Lateral regions engaged during ToM are the same regions known to support semantic memory
– Rely on scripts/schemas about how the average person would respond in a given situation
– Amnesic patients may rely on these lateral regions to carry out ToM tasks
Outline
Study 1: Is ToM impaired in amnesia?
Study 2: What are the unique neural correlates of EM and ToM?
Study 3 and 4: Are there certain conditions under which ToM depends on EM?
Study 3• ToM has been studied using tasks that typically
involve fictional characters or unfamiliar others (e.g., Baron-Cohen et al., 2001; Stone et al., 1998; Rabin et al., 2010; Spreng et al., 2010)
• However, in everyday life we typically infer the mental states of people we know well
– We have shared past experiences on which one can draw when imagining the thoughts/feelings of personally known others
Study 3
• Objective: To test whether different neural and cognitive mechanisms support mental state inferences of personally familiar vs. unfamiliar others
– Do individuals rely on EM to a greater extent for ToM involving personally familiar others?
– Do individuals rely on semantic to a greater extent for ToM involving unfamiliar others?
Study 3
• Participants:
– 18 healthy females (mean age = 19.44; SD = 1.24)
Methods Unknown others (ToM)Personal event; EM
Participant Unfamiliar people
Recall each event in as much detail as possible and focus on what you were thinking and feeling at the time.
Create a novel event and focus on what one person in the photo was thinking and feeling at the time. Do not draw on specific past experiences.
Rabin & Rosenbaum, 2012, NeuroImage
MethodsPersonally known others (pToM) Unknown others (ToM)Personal event; EM
Participant Participant’s brother Unfamiliar people
Recall each event in as much detail as possible and focus on what you were thinking and feeling at the time.
Create a novel event and focus on what one person in the photo was thinking and feeling at the time. Do not draw on specific past experiences.
Rabin & Rosenbaum, 2012, NeuroImage
Hypotheses• We expected that familiarity with the target person would
modulate the relationship between EM and ToM
1) Greater neural overlap between EM and pToM vs. ToM– Midline regions, including the hippocampus– Draw on past experiences to a greater extent when imagining
the mental states of personally known others
2) ToM vs. EM and pToM– Recruit lateral frontal and temporal regions to a greater extent– Script-like knowledge and semantic processing
Rabin & Rosenbaum., 2012, NeuroImage
Within Scanner Rating ScalesEM
pToM and ToM EM, pToM, ToM
• Postscan interview: Describe events
Rate the vividness of your memory/imagined event
1 2 3 4 Not vivid VIvid
Was your imagined event different from a memory?
1 2 3 4 Similar Different
Remember / Know / Don’t Know
Within Scanner Rating ScalesEM
pToM and ToM EM, pToM, ToM
• Postscan interview: Describe events
Rate the vividness of your memory/imagined event
1 2 3 4 Not vivid VIvid
Was your imagined event different from a memory?
1 2 3 4 Similar Different
Remember / Know / Don’t Know
fMRI Analyses
• Spatiotemporal Partial Least Squares (PLS)
• A data reduction technique that identifies the strongest effects in the data
• Data-driven approach (vs. using a priori contrasts)
• Early vs. Late phase of event generationMcIntosh et al., 2004
Results: Common network
Series1
-100-80-60-40-20
020406080
EM pToM ToM Num
Bra
in S
core
s
Pattern 1: EM and pToM vs. ToM
2 – 4 s
EM
10 – 12 s
Pattern 2: EM vs. pToM
EM
2 – 4 s
10 – 12 s
pToM vs. ToM
2 – 4 s
10 – 12 s
Study 3: Discussion• Familiarity with the target person in a ToM task
modulates the neural relationship between EM and ToM
• Multiple routes to ToM– Involve some balance between EM and semantic memory
• Strategy adopted likely depend on one’s relationship with the target person– Draw on past experiences for personally known others– Draw on semantic memory for unfamiliar others
Study 4
• Goal: Test whether EM, supported by the hippocampus, is necessary for imagining events from the perspective of personally known others.
• To address this question, we tested an amnesic person with impaired EM on the family photos test
Rabin et al., 2012, Frontiers in Psychology
Study 4
• Participants:
– Patient H.C. – A group of demographically matched controls
Rabin et al., 2012, Frontiers in Psychology
MethodsPersonally known others (pToM) Unknown others (ToM)Personal event; EM
Participant Participant’s brother Unfamiliar people
Recall each event in as much detail as possible and focus on what you were thinking and feeling at the time.
Create a novel event and focus on what one person in the photo was thinking and feeling at the time. Do not draw on specific past experiences.
Rabin et al., 2012, Frontiers in Psychology
Methods
• H.C. tested on this paradigm twice for reliability purposes
• Control participants tested only once
• Excluded H.C.’s EM events from the first testing session– Rehearsed events
Postscan Interview
• Photos with the highest vividness ratings were selected for a semi-structured interview
• Describe the events as they had been remembered/imagined in the scanner
• No time limit
Narrative Scoring
• Adapted Autobiographical Interview scoring procedure (Levine et al, 2002)
– Internal: event, temporal, perceptual, spatial, thought/emotion
– External: semantic facts, details that were irrelevant to the central event, repetitions, metacognitive statement
Narrative Scoring
• Adapted Autobiographical Interview scoring procedure (Levine et al, 2002)
– Internal: event, temporal, perceptual, spatial, thought/emotion
– External: semantic facts, details that were irrelevant to the central event, repetitions, metacognitive statement
Autobiographical InterviewLevine et al. 2002
Descriptive vs. Elaborative Details
• Internal details were further divided into descriptive vs. elaborative details
– Descriptive detail – details that describe the visual content of the photo
– Elaborative detail – details that go beyond what is visually depicted in the photo
Rabin et al., 2012, Frontiers in Psychology
Descriptive vs. Elaborative Details
Analyses
• Mean number of elaborative details
• Mean proportion of elaborative details/total internal details– Weight given to elaborative vs. descriptive
details
• Crawford’s t -test (Crawford & Howell, 1998)
Rabin et al., 2012, Frontiers in Psychology
pToM ToM EM0
1
2
3
4
5
6
7
8
9
HCControls
Mean number of elaborative details per event
*
*
Rabin et al., 2012, Frontiers in Psychology
Mean proportion of elaborative : total internal details
pToM ToM EM0
0.2
0.4
0.6
0.8
1
HC Controls
*
*
Rabin et al., 2012, Frontiers in Psychology
Qualitative Nature of Responses
• H.C.– “they’re both really excited”– “he looks really happy”
• Control– “they were probably afraid but they are trying
to look cool”– “her mother was pleased that her daughter
was having so much fun”Rabin et al., 2012, Frontiers in Psychology
Study 4: Discussion
• H.C. impaired at pToM and EM
• H.C’s performance on pToM was not at floor
• Approximately 50% of H.C.’s pToM narratives were comprised of descriptive details– Relied on visual information depicted in the
photos– Compensatory strategy?
Rabin, Carson et al., 2012, Frontiers in Psychology
Study 4: Discussion cont.
• H.C. impaired at pToM and EM but not ToM– Therefore may need EM for pToM but not ToM
• These findings are consistent with:– Previous fMRI findings (Rabin & Rosenbaum, 2012)
– H.C.’s intact performance on standard ToM tests (Rabin et al., 2012)
• Need to replicate this finding in other amnesic cases
General Conclusions
Common Core Network
Schacter, Addis & Buckner, 2008, Nat. Neurosci.
What is Amnesia?
Impaired Abilities
• Episodic memory (EM)
• Future Thinking
• ToM involving personally known others
Spared Abilities
• General intelligence
• Semantic memory
• Procedural memory
• Working memory
• Attention
Future Directions
• Scanning H.C. with fMRI on the EM, pToM, and ToM paradigm
Future Directions
• Scanning H.C. with fMRI on the EM, pToM, and ToM paradigm
EM pToM ToM
Acknowledgements
• Shayna Rosenbaum
• Nicole Carson
• Cognitive Neuroscience Lab at York University
Thank you
Questions?
Mean number of elaborative details per event
* p < .08, p < .05
The mean proportion of elaborative-to-total-number of internal detail
Rabin et al., 2012, Frontiers in Psychology
* p < .01, p < .001