1. Imagery Rescripting and Dual Representation Theory
Chris R. Brewin
Traumatic Stress Clinic
Camden & Islington Mental Health and Social Care Trust
Subdepartment of Clinical Health Psychology, UCL
November 2005
© Chris R. Brewin©

2. Little understanding of PTSD treatment
Why are both exposure and cognitive methods effective?
Do they work the same way? (associative processes vs. explicit verbal reasoning)
What is “emotional processing” and does it provide an adequate basis to explain how trauma treatment works?
Are memories in fact “processed” or “transformed”?
November 2005
© Chris R. Brewin©

3. Things to explain Different types of memory Normal recovery processes
ordinary memories
flashbacks
Normal recovery processes
What goes wrong in PTSD?
What’s so special about constructing a trauma narrative?
November 2005
© Chris R. Brewin©

4. Single vs. dual representations
The standard view (e.g. Foa): trauma memories are fragmented; narratives must be organised
Dual representations (Janet, Brown & Kulik, Pillemer): separate image-based representations (highly sensory, automatic retrieval, reliving) and verbal representations (under conscious control, can be edited)
November 2005
© Chris R. Brewin©

5. Two systems of reasoning
One is associative and automatic. It computes similarities and differences between inputs and stored information
The other is rule-based and deliberate. The world is described in conceptual terms by describing a process that is logical or causal
November 2005
© Chris R. Brewin©

6. Brain systems controlling fear responses
Cortex
Hippocampus
Sensory
input +
+ve
Fear
system
Amygdala
+ ve
November 2005
© Chris R. Brewin©

7. Brain systems controlling fear responses Non-hippocampal route Hippocampal route
Rapid
Low-level feature & object detection
Little coding of context
Low-level pattern matching system
Activates fear
Relatively slow
High-level feature discrimination
Encodes temporal and spatial context
Can be used flexibly to increase and decrease fear
November 2005
© Chris R. Brewin©

8. Dual representation model
Thoughts
Rumination
Primary and
secondary
emotions
VAM
system
Contents of
consciousness
Trauma
stimuli
Meaning
analysis
Flashbacks
Reliving
Primary
emotions
SAM
system
November 2005
© Chris R. Brewin©

9. Verbally Accessible Memory (VAM system)
Information initially stored in hippocampus
Through rehearsal becomes consolidated into the long-term autobiographical memory store
Memory enhanced by moderate levels of arousal but impaired by very high arousal
Constructive process supporting explicit memory, strategic retrieval, meaning-making, sense of self, and social interaction
November 2005
© Chris R. Brewin©

10. Situationally accessible memory (SAM system)
High levels of fear create indelible non-hippocampally-based representations
Remains informationally isolated (dissociated)
Triggered automatically in all-or-none fashion
Unresponsive to social situations
Supports flashbacks, performance on implicit memory tasks
Information directed very rapidly to amygdala
November 2005
© Chris R. Brewin©

11. Is this the same as implicit and explicit memory?
No, because implicit memory does not have a conscious component. In contrast, flashbacks usually involve conscious awareness of the trauma
At the same time the SAM system has many characteristics usually ascribed to implicit memory
November 2005
© Chris R. Brewin©

12. Characteristics of VAMs and SAMs VAMs SAMs
Integrated with and interact with other autobiographical data
Can be retrieved and edited
Sense of context including present and past
Reliving in present
Fragmented sensory data or ‘video clips’
Absence of context
Do not interact with autobiographical memory system
Cannot be directly retrieved or edited
November 2005
© Chris R. Brewin©

13. A narrative study of ordinary memories and flashbacks (Hellawell & Brewin, 2002, 2004)
57 patients with a DSM-IV diagnosis of PTSD completed a written narrative of their traumatic event (26 combat veterans, 22 assault victims, and 9 accident victims). After completing the narrative patients identified those sections corresponding to flashbacks and ordinary memories. Word counts were conducted on these sections and proportional scores calculated to correct for the total number of words used in flashback and ordinary memory sections.
November 2005
© Chris R. Brewin©

14. Features of ordinary memories vs
Features of ordinary memories vs. flashbacks (proportions of total text)
Ordinary Flashbacks
Content memories Z
Visual ***
Proprioceptive ***
Auditory ***
Olfactory **
Taste
Motion ***
November 2005
© Chris R. Brewin©

15. Features of ordinary memories vs. flashbacks
Ordinary Flashbacks
Content memories Z
Proportion of total text
Mention of death ***
Primary emotions ***
Secondary emotions ***
November 2005
© Chris R. Brewin©

16. Task performance during narrative
November 2005
© Chris R. Brewin©

17. Understanding symptoms VAM-related SAM-related
Ordinary memories
Evaluative thoughts
Concerns about the future
Secondary emotions
sadness
guilt
Flashbacks
Nightmares
Trauma-specific (primary) emotions
fear
helplessness
horror
November 2005
© Chris R. Brewin©

18. Specific responses in PTSD
The trauma threatens identity through its potential impact on the integrity of the body, of the mind, or of important relationships
The release of hormones such as cortisol impair functioning of brain structures such as the prefrontal cortex and hippocampus that are critical for memory and identity
This is experienced as a disruption to identity (depersonalisation) or to the person’s relation to the world (derealisation)
November 2005
© Chris R. Brewin©

19. Specific responses in PTSD
Conscious attention is narrowly focussed on threatening aspects of the situation
Verbally accessible (VAM) memories dependent on processing by a sparse network of neurones in the hippocampus (fast learning system) are fragmented and incomplete
Sensory images linked with emotional responses are recorded in an alternative, fast, situationally accessible memory (SAM) system not dependent on hippocampal processing
November 2005
© Chris R. Brewin©

20. Psychological consequences
Because image-based (SAM) memories are more detailed, they are automatically retrieved by a wider range of trauma reminders
Because the memories involve lower levels of information-processing they have no mechanism for encoding context e.g. time
When these memories are retrieved they are therefore reexperienced in the present
Memories intrude in parallel with other thoughts
November 2005
© Chris R. Brewin©

21. Normal recovery process - 1
Traumatic information laid down in VAM (limited) and SAM memory systems
Over next few days flashbacks lead to copying of extra information from the SAM to the VAM system
Limited capacity system means little information transferred at one time
November 2005
© Chris R. Brewin©

22. Normal recovery process - 2
VAM memory creates copies locating context and time
Trauma reminders lead to retrieval competition between SAM memories and VAM copies
If good match to SAM memories, VAM copies begin to inhibit amygdala from responding inappropriately
November 2005
© Chris R. Brewin©

23. Many trauma cues, fear system activated
Incomplete
VAM memory
F1-F10
Sensory
input
F1-F20
Fear
system
activated
SAM memory
F1-F20
November 2005
© Chris R. Brewin©

24. Dual representation model
Thoughts
Rumination
Primary and
secondary
emotions
VAM
system
Contents of
consciousness
Trauma
stimuli
Meaning
analysis
Flashbacks
Reliving
Primary
emotions
SAM
system
November 2005
© Chris R. Brewin©

25. Many trauma cues, fear system inhibited
Complete
VAM memory
F1-F20
Sensory
input
F1-F20
Fear
system
activated
SAM memory
F1-F20
November 2005
© Chris R. Brewin©

26. What goes wrong in PTSD? - 1
The VAM system fails to make a good copy of the information in SAM
impairment of consciousness
dissociation (induced by helplessness)
deliberate avoidance
Information remains isolated in SAM
When SAMs are triggered the fear system is not inhibited
November 2005
© Chris R. Brewin©

27. What goes wrong in PTSD? - 2
Interference with previous knowledge or goals, leading to secondary emotions such as anger or shame
Intrusion of involuntary VAMs and related thoughts triggered by external or internal cues
VAM intrusions may or may not lead to repeated SAM intrusions (flashbacks)
November 2005
© Chris R. Brewin©

28. Therapy - flashbacks and nightmares
Detailed oral narrative
Detailed written narrative
Prolonged exposure
EMDR
Imaginal rescripting
These are all based on an automatic, associative form of reasoning
November 2005
© Chris R. Brewin©

29. Therapy principles Identify content of flashbacks
Focus exposure on these and on other moments of intense emotion (hotspots)
Modulate arousal so that individual is fully aware and does not dissociate (graded exposure, 3rd person narratives, typing vs. writing)
November 2005
© Chris R. Brewin©

30. Therapy principles
Develop detailed VAM memory that can compete with SAMs and has associative links to safety cues and other memories
Enhance retrievability through practice, self-generation, or distinctiveness
Increase distinctiveness through rescripting
Check for avoidance and safety behaviors
Check for additional triggers with in vivo exercises
November 2005
© Chris R. Brewin©

31. Recap
The original memories are not “processed” or “transformed” but remain intact
“Processing” consists of the construction of new memories that are similar enough to be retrieved by trauma reminders but different enough to preserve positive feelings
The principles of constructivism and retrieval competition provide a parsimonious explanation of response to treatment
November 2005
© Chris R. Brewin©

32. “ Bibliography
Brewin, C.R. (2003). Posttraumatic stress disorder: Malady or myth? New Haven: Yale University Press.
Brewin, C.R. (2001). A cognitive neuroscience account of posttraumatic stress disorder and its treatment. Behaviour Research and Therapy, 39,
Hellawell, S.J. & Brewin, C.R. (2002). A comparison of flashbacks and ordinary autobiographical memories of trauma: Cognitive resources and behavioural observations. Behaviour Research and Therapy, 40,
 Hellawell, S.J. & Brewin, C.R. (2004). A comparison of flashbacks and ordinary autobiographical memories of trauma: Content and language. Behaviour Research and Therapy, 42, 1-12.
Holmes, E.A., Brewin, C.R., & Hennessy, R.G. (2004). Trauma films, information processing, and intrusive memory development. Journal of Experimental Psychology: General, 133, 3-22.
November 2005
© Chris R. Brewin©