Lecture_22

Report
Lecture 22 – Psyco 350, B1
Winter, 2011
N. R. Brown
Psyco 350 Lec #22– Slide 1
Outline
•
Memory Issues in PTSD
•
•
Background
Dual-representation Theory (& Data)
Holmes, Brewin, & Hennessy, 2003
•
The Mnemonic Model (& Data)
Psyco 350 Lec #22– Slide 2
Post-traumatic Stress Disorder:
Background
Psyco 350 Lec #22– Slide 3
DSM-IV Criterion A
The person has been exposed to a traumatic event in
which both of the following have been present:
(1 – The Event) The person experienced, witnessed,
or was confronted with an event or events that
involved actual or threatened death or serious injury,
or a threat to the physical integrity of self or others
(2 – Peritraumatic Reaction) the person's response
involved intense fear, helplessness, or horror.
Psyco 350 Lec #22– Slide 4
DSM-IV Criteria B-F
B. reexperiencing of the traumatic event
C. avoidance of stimuli associated w/ trauma and
numbing of general responsiveness
D. increased arousal
E. symptoms present for more than 1 month
F. clinically significant impairment in social,
occupational, or other important areas of
functioning
Psyco 350 Lec #22– Slide 5
Dual- Representation Theory (DRT)
Psyco 350 Lec #22– Slide 6
DRT: Holmes, Brewin, & Hennesy (2004)
Two type of event information
1. Verbally Accessible Memory (VAM)
“ordinary autobiographical memory”
requires “high-level of conscious processing”
2. Situationally Accessible Memory (SAM)
“stores sensory information, mostly… in the
form of visual images”
Psyco 350 Lec #22– Slide 7
DRT: SAM on Its Own
SAM Retrieval:
triggered by exposure to “relevant” cues
accessed automatically
Reaction to SAM:
re-experience event
emotion-laden flashbacks
strong affective response
Psyco 350 Lec #22– Slide 8
DRT: Further Assumptions
VAM blocks SAM:
controls & contextualizes SAM-based
responses
WM-systems & the creation SAMs & VAMS:
Verbal WM required for VAMs
Visuo-spatial WM required for SAMs
Psyco 350 Lec #22– Slide 9
DRT: Implications
Creation of PTSD-evoking representations:
Dissociative reactions to traumatic event knocks-out
WM capacity necessary for VAM creation
SAM encoded regardless VAM-less SAMs
PTSD symptoms
Psyco 350 Lec #22– Slide 10
Testing DRT w/ Dual Task Design
General Paradigm:
Watch horrific film while engaged in either:
(a) spatial task
(b) verbal task
General Predictions:
spatial task  knock out SAM  reduce PTSD
symptoms
verbal task  knock out VAM  increase PTSD
symptoms.
Psyco 350 Lec #22– Slide 11
The Experiment(s)
Participants:
Healthy, young adults
 20/group
Materials:
12.5 min film – actual traffic accidents
Instructions:
Watch film for later memory test
Psyco 350 Lec #22– Slide 12
The Experiment(s)
Concurrent Tasks (between-subjects):
Control – no concurrent task
Visual-spatial inference – tap out a preseficed
pattern on buttons
Verbal-interference – count backwards by 3s
Main DV:
# of intrusive memories recalled in 7-day diary
Psyco 350 Lec #22– Slide 13
The Experiment(s)
Expectation:
Counting interferes w/ VAM creation
Tapping interferes w/ SAM creation
Prediction:
# intrusive memories:
counting > control > interference
Psyco 350 Lec #22– Slide 14
Results: # of Intrusions
10
As predicated:
• tapping < control
E xp . 2
9
# o f In tru sio n s
8
7
6
5
4
3
2
1
0
C o n tro l
T a p p in g
Psyco 350 Lec #22– Slide 15
Results: # of Intrusions
10
E xp . 2
As predicated:
• tapping < control
• counting > control
E xp . 3
9
# o f In tru sio n s
8
7
6
5
4
3
2
1
0
C o n tro l
T a p p in g
Psyco 350 Lec #22– Slide 16
C o n tro l
C o u n tin g
DRT: Discussion
DRT correctly predictions intrusion patterns.
But:
• Are these data PTSD-relevant?
• If so,
–
–
–
How do VAM-less SAMs create PTSD?
How do VAMs inhibit SAM-trigged responses?
PTSD in non-humans?
Psyco 350 Lec #22– Slide 17
The Mnemonic “Model”
Psyco 350 Lec #22– Slide 18
Rubin, Berntsen, & Klindt-Johansen.
(2009) Psychological Review
A Memory-based Model of Post-traumatic Stress
Disorder: Evaluating Basic Assumptions
Underlying PTSD Diagnosis
A telling and misleading title.
Psyco 350 Lec #22– Slide 19
The “Models”
Proximal Event: A1
event & A2 reaction
Proximal Event: A1
event & A2 reaction
Psyco 350 Lec #22– Slide 20
Response:
Symptoms
Memory
for A1& A2
Response:
Symptoms
Support for Mnemonic Position
“most direct evidence for ... memory ...as a
causal agent is that observation that
eliminating or enhancing memory in various
ways changes PTSD symptom severity”
Psyco 350 Lec #22– Slide 21
Memory & PTSD
Amnesia reduces or eliminates PTSD
• Organic amnesia – traumatic brain injury
• Pharmacologically-induced amnesia
– Propranolol treatment reduced PTSD symptoms in
emergency room patients (Pitman et al, 2002)
• Childhood Amnesia
– Before 3: No PTSD
– 3-to-7: PTSD symptoms increase w/ age
– After 7: PTSD unrelated to age
Psyco 350 Lec #22– Slide 22
Memory & PTSD
PTSD symptoms , as availability of traumatic
memory 
• Method: correlate Centrality of Event Scale
(CES; B&R, 2006, 2007) w/ PTSD symptom.
– CES measures importance of traumatic event:
• To personal identity
• As a turning point
• As a reference point
• Results: r’s ranging from .35 to .51
Psyco 350 Lec #22– Slide 23
Questions
• Is the DSM “model” a strawman?
• What is required to make the mnemonic
“model” a model?
• Does anyone ever consider the material
consequences of traumatic events and their
relation to PTSD?
Psyco 350 Lec #22– Slide 24

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