Neurophysiology and Hypnosis

1
Neurophysiology and Hypnosis

• The physiology of therapy

2
Ramachandran Reith Lectures 2003

• The boundary between neurology and psychiatry
  is becoming increasingly blurred and its only a
  matter of time before psychiatry becomes just
  another branch of neurology.

3
Five separate strands

• New perspectives in depression
• New perspectives in memory
• New perspectives in emotion
• New perspectives in well-being
• New perspectives in neuro-anatomy,
  neuro-chemistry and neuro-physiology

4
New perspectives in neuro-anatomy,
neuro-chemistry and neuro-physiology
5
Conditioned Learning
1 Hebb d (1949), The organisation of behaviour
Wiley, New York
2 Bailey C, Kandel E (1993) Structural changes
accompanying memory storage Annual Rev.
Neuroscience 55 397-426

• How are memories written, and associations
  strengthened in the brain.
• Hebbs proposed a model in 1949 that fragile,
  dynamic memory traces would be translated into
  stable, long term memory.1
• Subsequent research has teased out some of the
  details about how this is done.
• Eric Kandel working with the sea slug Aplysia
  discovered that short term memory triggers a
  cascade of molecular changes at the post synaptic
  neurone.2 This enhances the signal to the motor
  neurons, making the muscle contract longer.

6
(No Transcript)
7
(No Transcript)
8
The Human Factor

• Studies of associative learning in mammals has
  come mainly from studies of the Hippocampus, by
  co-incidence one of the most important brain
  structures involved in the processing of memory
  short term and long term. This is partly because
  sections are easy to obtain and study.

9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
So how does the brain learn? How do two separate
signals become associated?
13
2 Types of Post Synaptic Receptor

• Most synapses in the brain are actually
  inhibitory.
• However the excitatory synapses are the ones that
  deal with associative learning.
• Most excitatory sinuses are glutamate mediated.
• Glutamate then stimulates 2 types of post
  synaptic synapse. NMDA and AMPA receptors.

14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
LTPLong Term PotentiationLTDLong Term
DepressionSynaptic Plasticity
18
LTP

• Calcium influx induces many changes depending on
  the rate of stimulus, in LTP it triggers the
  expression of mRNA in the relevant post-synaptic
  terminal only (not the whole cell)
• Exact mechanism is not known, many chemicals
  could cause this increase.
• CREB is one of these Cyclic AMP response element
  binding protein. It binds to DNA

19
Phosphorylation of CREB may be the key to LTP.
Interestingly CREB like molecules have also been
shown to exhibit prion like behaviour, so that
above a certain concentration it becomes
permanently switched on.1
1 Kausik S, Lindquist S, Kandel E (2003) A
neuronal isoform of the aplysia CPEB has prion
like properties Cell vol 115, 873-891
20
Hippocampus.Place cells and Head direction cells

• In 1984 while James Ranck was attempting to find
  particular neurons in a rat cortex his electrode
  slipped and went to the wrong area. The cell the
  measuring electrode was in however responded to
  the direction that the rat pointed its head in,
  but only one direction stimulated that cell with
  a very narrow margin of stimulation for
  directions within a few degrees either side.
  Independent of position or place or movement the
  cells still responded only to that initial
  compass bearing. He called these head
  direction cells.

21
Place cells

• Then other researchers discovered cells in the
  rat hippocampus that appeared to respond only to
  one place in their environment. Every time the
  rat passed that spot the cell would fire again
  within a very narrow margin. These they called
  place cells.
• In October 1998 Edmund Rolls discovered similar
  head direction cells for head direction in
  macaques
• The cells he discovered don't keep track of where
  the animal is, but where it is looking, encoding
  positions "out there" in space.
• This fits with the much more visual world of the
  primate

22
(No Transcript)
23
Head Direction in Humans

• In primates head direction cells are found in the
  mamillary bodies, as can be seen right next to
  the hippocampus.
• In humans lesions of the mamillary bodies leads
  to a particular pattern of memory loss in which
  context cannot be recalled properly.

24
Place cells

• So the CA1 cells of the hippocampus become
  markers on a visuo-spatial map that we carry in
  our head of any particular space. Effectively we
  carry a road map of where we are and, through
  memory, of all the places we have been in the
  past.

25
Place cells
1 Experience-dependent phase reversal of
hippocampal neuron firing during REM sleep Poe G
et al Brain Research 855 (2000) 176-180

• After the animal enters a new environment a new
  set of place cells is imprinted on the cells in
  the CA1 region, a new map is put down. When the
  animal rests, underlying theta rhythms stimulate
  these cells and strengthen the synapses in this
  particular map (i.e. strengthens the links to the
  places of significance). Then the whole map is
  written over the next few days to the neo-cortex,
  and the place cells then start to fire in a
  different rhythm, and with the change in the
  co-ordination of the theta rhythm from the
  thalamus these cells become out of phase1
  leading as we have already seen to long term
  depression. The hippocampus within a week has
  handed the entire map to the neo-cortex for long
  term storage and is ready for a new map.

26
During sleep the hippocampus plays snippets to
the cortex (in REM) and the cortex then replies
(in Slow wave sleep), strengthening significant
connections with events from past experience.
Thus without slow wave sleep procedural memory
cannot improve.
27

• The hippocampus is the patient, troubled with
  memories of the day, and the cortex is the
  therapist. "In the first part, during the
  slow-wave sleep, they talk about what happened,
  replaying the autobiographical memories from the
  hippocampus. During REM the cortex replies, and
  they look at how this information fits together.
  More slow-wave sleep, more explanation. The two
  memory systems talk back and forth trying to come
  to a consensus on what these memories mean.
  Stickgold R from New Scientist

28
The Amygdala

• The amygdala is a very ancient structure which is
  very active in aversive conditioning. It has
  direct links to the hippocampus and the
  hypothalamus and the pre-frontal cortex. It has
  two basic nuclei the medial amygdalar nucleus
  which connects directly to the hypothalamus and
  stimulates production of ACTH and adrenaline, and
  the lateral nuclei which inhibits the medial
  nuclei.

29
(No Transcript)
30
(No Transcript)
31
Amygdala connections
32
The pre-frontal cortex PFC

• The prefrontal cortex PFC combines information
  from different modalities to take account of the
  rapidly changing exigencies of the
  environment.Consists of orbitofrontal OFC and
  dorsolateral PFC.
• The orbitofrontal PFC contains the secondary
  taste cortex and the secondary olfactory cortex.
  Cells combine information from the primary areas
  with visual information and combine this with
  appetitive information from the hypothalamus to
  give each object a value in the current
  circumstances so that the organism can be given
  the appropriate motivation for action. Thus
  information on an object in the visual cortex (a
  mate) will always be the same, but on hitting the
  pre-frontal cortex will be given a value
  depending on what other factors are operating
  internally (hunger, thirst).

33
(No Transcript)
34
Reward cells.

• The cells in the OFC thus will be stimulated by
  the sight of food and measure the degree of
  hunger internally and if action is decided the
  electrical discharge of the cell is used to drive
  the motor action required via the cingulate to
  the pre-motor cortex.

35
(No Transcript)
36
(No Transcript)
37
Orbitofrontal cortex

• As well as cells that respond to the sight of
  food there are cells that fire when the food is
  obtained, and cells that fire off when the food
  is not obtained (although the visual cue
  suggested it) or where the taste is not as
  suggested i.e. bitter.
• In a different part of the OFC there are cells
  that respond to punishment or lack of punishment
  (this is involved in extinction) i.e. expected
  punishment doesnt come.
• Reward cells are medial, punishment cells are
  lateral.

38
Aversive Conditioning

• In aversive conditioning, the punishment is
  represented in the orbitofrontal cortex, and the
  amygdala. The pain (CS) is written onto the
  orbitofrontal cell along with the UCS (visual
  cue) and a connection rapidly set up between the
  two modalities while the same happens in the
  amygdala.
• Conditioning and extinction use the same areas so
  have the same connections, however the difference
  between conditioning and extinction is that the
  lateral nucleus of the amygdala is stimulated,
  presumably by cells that signal a lack of
  punishment and this new memory then inhibits the
  output of the amygdala.

39
(No Transcript)
40
Extinction
41
Dorsolateral Prefrontal Cortex

• Dorsolateral PFC carries information about and
  rewards and punishments, but in this case in
  relation to temporo-spatial information ie
  left/right up/down to hold a object in a
  position in working memory while attending to it.
  It also holds all working memory functions.
• Working memory refers to a number of brain
  regions held under the executive control of the
  DLPFC holding information in a feedback loop.

42
Attractor NetworksHolding Working Memory
43
(No Transcript)
44

• So why have 2 systems of association in the
  primate brain? Essentially they are carrying out
  the same functions.
• However Primates are essentially visual, encoding
  2.1 million colours with better colour vision
  than any other species (extra colour cone over
  all other species). Primates feed off over 100
  different food types and need a rapid way of
  ascribing values to different food groups.

45
Pre Frontal Cortex
1 Ghazanafar A, Santos L (2004) Primate brains
in the wild the sensory basis for social
interactions Nature Reviews Neuroscience vol 5
603-616

• Even more important, higher primates and
  particularly humans need to be able to respond
  rapidly to changing social conditions, relying on
  almost instant changes in the reward/punishment
  contingencies in a social group.
• There is a large input from all the face areas in
  the Inferior Temporal Cortex, for individual
  faces and for facial expressions. These systems
  are very sensitive to changes of facial
  expression and to direction of head combined with
  direction of gaze1, as gaze and head direction
  are vitally important indicators of status

46
Important
1 Davidson R (1998) Affective style and
affective disorders perspectives from affective
neuroscience. Cogn. Emotion 7 115-138

• Notice that the dorsolateral PFC has a strong
  inhibitory effect on the amygdala.
• Davidson1 has proposed that that in humans and
  possibly other primates the major inhibitory
  influence on the amygdala is from the pre-frontal
  cortex.
• Consistent with this idea PET studies of the
  amygdala have shown a reciprocal inverse coupling
  of metabolism in these two areas2.
• Davidson proposes that this mechanism may be
  responsible for the dampening of negative affect
  and shortening of its time duration in
  individuals with strong working memory, which may
  be a trait or conditioned3. This is reinforced by
  Brewins work (see later)
• The best way to reinforce working memory is
  active generative visualisation or the
  performance of multiple tasks simultaneously
  (visualisation and Thought field therapy)

2 Abercrombie H et al (1996) Medial Prefrontal
and amygdalar glucose metabolism indepressed and
control subjects an FDG PET study
Psychophisiology 33 s17
47
(No Transcript)
48
New perspectives in memory

• Consolidation and Re-consolidation

49
Memory consolidation and reconsolidation
1 Misanin JR et al (1968) Retrograde amnesia
produced by electroconvulsive shock after
reactivation of a consolidated memory trace

• Prior to 1968 memories were thought to gradually
  enter a consolidated unchanging state
• Lewis (1968)1 and colleagues gave
  electro-convulsive shock (ECS) 24 hours after
  fear conditioning.This was ineffective in
  generating amnesia.
• However if the memory was reactivated before ECS
  it was effective in generating amnesia.
• This was used to treat psychoses at the time
  (Rubin 19692 19763)
• Therefore reactivation of a consolidated memory
  presumably returned it to a labile state , which
  elicited another time dependent memory process
  similar to that seen after new learning.
• This phenomenon now called reconsolidation. This
  is defined by the amnesic agent only being
  effective after memory reactivation, not if
  reactivation omitted

2 Rubin RD et al (1969) New application of ECT
Advances in Behaviour Therapy 1968 (Rubin RD,.
Franks C et al eds) pp 37-44 Academic press
3 Rubin RD (1976) Clinical use of retrograde
amnesia produced by electroconvulsive shock a
conditioning hypothesis Can Psych association J
21, 87-90
50
Reconsolidation
1 Nader K et al (2000) Fear Memories require
protein synthesis in the amygdala for
reconsolidation after retrieval Nature 406
722-726

• As with so much Science, mostly forgotten until
  Nader 2000.1
• In the meantime it had become clear that
• 1 long term memory (LTM) formation was dependent
  on the recruitment of NMDA receptors stimulating
  calcium release into active dendrites triggering
  calmudolin which produces increasing protein
  production.
• 2 suppressing protein formation in the crucial
  early formation of Long Term Memory erased the
  memory. (using actinomycin D)
• The reconsolidation was blocked by NMDA receptor
  blockers only in animals exposed to the context
  before administration2. This is a cross species
  effect (crustaceans to mammals)

2 Sara SJ (2000) Strengthening the shaky trace
through retrieval Nat. Rev Neuroscience 1 212-213
51
(No Transcript)
52
(No Transcript)
53
Reconsolidation

• Nader (2000) found that if a memory was revived
  just before administration of actinomycin D then
  the animal became totally amnesic
• If the memory was not revived there was no change.

54
Reconsolidation
1 Anokhin KV et al (2002) Reminder effects
reconsolidation or retrieval deficit?
Pharmacological dissection with protein synthesis
inhibitors following reminder for a passive
avoidance task in young chicks Eur J Neuroscien
15 1759-1765

• Largest study on re-consolidation1 established
  that
• 1 on re-testing, the amnesia produced by blockade
  of reconsolidation (but not consolidation) could
  recover.
• 2 reconsolidation was more sensitive to amnesic
  challenge than consolidation.
• 3 reconsolidation occurred faster than
  consolidation

55
Reconsolidation

• Found to involve CREB transcription factor Ca2
  response element binding protein.
• CREB has downstream immediate early gene targets
  Fos and zif268 these are found in the amygdala
  during auditory reactivation and zif268 in the
  amygdala and hippocampus in contextual memory
  reactivation.
• In the hippocampus consolidation occurs at a
  second level that lasts from 1-more weeks called
  systems consolidation. The recent memories are
  slowly erased from the hippocampus and written to
  the cerebral cortex. This occurs by the recently
  reinforced memories slowly over 3-4 days changing
  their phase of firing so that the potentiation
  becomes extinguished.
• Lesions of the hippocampus 45 days after
  conditioning has no effect on the subsequent
  expression of contextual fear conditioning.
  However if the context is reactivated even 90
  seconds before the lesion, amnesia occurs,
  showing that the memory returns to a hippocampal
  dependent state which lasts only 2-3 days.
• The decreased length of time for which the
  hippocampus is necessary after reactivation is
  consistent with the updating of neocortical
  memories even though cortical memories are
  consolidated.

56
Reconsolidation

• New research April 2004 Science
• Independent Cellular processes for hippocampal
  memory consolidation and reconsolidation
• Lee J Everitt B Thomas K
• Infused different antisense oligodeoxynucleotide
  s in the dorsal hippocampus to establish the
  function of two separate components in memory,
  antisense Brain Derived Neurotrophic Factor
  (BDNF) and antisense Zif268
• Their experiment established BDNF blocking
  prevented consolidation of memory (causing
  amnesia) but had no effect on reconsolidation.
  Zif268 blocking prevented reconsolidation of
  memory (causing amnesia) but had no effect on
  consolidation
• Therefore reconsolidation of fear memory does not
  engage the same molecular systems as
  consolidation.

57
Reconsolidation

• Crucially the Zif268 antisense infusion had no
  effect on fear memory (measured by animal
  freezing) when the animal was not re-exposed to
  the context.
• The disruption of re-consolidation was critically
  dependent on re-exposure to the training context
  as demonstrated by the lack of amnesia when the
  reactivation trial was omitted
• The crucial area was found to be the CA1 area in
  the dorsal hippocampus where 2 hours after memory
  retrieval the level of Zif268 was maximal.

58
Reconsolidation-important points

• Memory is a plastic and transient affair,
  whenever a memory is recalled it is able to be
  modified
• Memory is in a dynamic balance
• Implications for treatment of any client using
  regression or vivid recall
• Memory may be modified by many psychological
  tools, these will probably soon be explicable
  (Rapid Eye Movement, Thought Field Therapy)
• Does Brewins experiment show that engaging
  attention may alter memories by suppressing the
  amygdala through inhibitory pathways from PFC?

59
Important points

• The hippocampus will recall contextual
  information in 90 seconds.
• Reconsolidation happens in only 2 days,
  consolidation takes a week and it takes 45 days
  to completely remove a consolidated memory to the
  cortex.
• These techniques have been successfully used in
  ECT so regression probably fulfils the same
  purpose.

60
In Therapeutic Terms
Review Memory traces unbound Nader K (2003)
Trends in Neurosciences Vol 26 No 2

• The past is the past, and we cannot change
  the past, but we can change the way we feel about
  the past with more happy choices for the future.

61
New Perspectives in Emotion

• The feeling of what happens Antonio Damasio
  Vantage Press 2000
• Damasio hypothesises that there are 3 levels of
  consciousness
• 1. The Proto-self (wakefulness ability to react
  to objects) leads to second order maps of
  organism/object relationship.
• 2. Core consciousness allows enhanced attention
  and working memory leads to conventional memory
  combines with autobiographical memory and leads
  to
• 3. Extended consciousness

62
Emotions (neurology)

• Emotions are a complicated collection of chemical
  and Neural responses, forming a pattern all
  emotions have some kind of regulatory role to
  play, leading to the creation of circumstances
  that are advantageous to the organism.

63
Emotions (therapy)

• I have respect for the part of you that is
  causing this feeling, you got where you are
  today, you are successful in doing many of the
  things you do and I am convinced that this part
  of you that is causing this feeling although you
  may not appreciate it is trying to do something
  positive on your behalf.

64
(No Transcript)
65
Types of Emotion

• Primaryhappiness sadness anger fear surprise
  disgust
• Secondary or Social embarrassment jealousy guilt
  pride
• Background well-being malaise calm tension

66
Conscious/Unconscious?

• It is not necessary to have extended
  consciousness to use emotions.
• The presence of emotion and feeling may be
  totally unconscious, but still cause changes in
  the skeletal and autonomic nervous system.
• Examples from people with no autobiographical
  memoryDavid no autobiographical memory but
  flinches when introduced to bad guy. Woman with
  skin conductance changes to faces she has no
  memory of but are family or friends.

67
Theories of Emotion
68

• James-Lange theory
• We experience emotion in response to
  physiological changes. Sensory system reacts to
  the changes evoked by the brain and it is this
  sensation that constitutes the emotion
• Canon Bard theory.
• Emotional expression can occur independently of
  emotional expression.

69

• Canon-Bard based their theory on certain
  observations on animals and humans with
  transaction of the spinal cord. This putatively
  removed the the ability to sense sensations below
  the level of the cut, but did not appear to
  effect the expression of emotion in the animals
  (similar in humans)

70
Vagal Afferents
(1)Peripheral arousal related hormones modulate
noradrenaline release in the hippocampus via
influences on brainstem nuclei Miyashita T,
Williams C (2004) Behavioural Brain Research vol
153 issue 1 pp 87-95

• However the modern evidence reveals a myriad of
  effects that the vagus transmits.
• Noradrenaline peripherally administered increased
  the activity in the NTS (nuleus tractus
  solitaris-vagal nucleus) this in turn causes
  increased noradrenaline in the hippocampus, so
  increases memory storage. (1)
• 80 of the vagus nerve is afferent fibres
  relaying information to the brain.

71

• What Canon failed to realise is that the relaying
  of these vagal afferents is how the brain
  recognises the physiological changes in the
  organs and particularly the effects of systemic
  amines. Also the cranial nerves have a huge
  emotional impact, the trigeminal and the facial
  nerve conveying the state of the facial muscles.

72
FEELINGS

• Canon also said that the fact that cats and dogs
  with cord transection and vagal transection
  displayed the facial characteristics of emotion
  meant that these lesion left emotion intact.
  However Damasio says the presence of the pathway
  for facial reactions to stimuli does not denote
  any feeling only reaction.

73
(No Transcript)
74
(No Transcript)
75
Important

• An emotion may not be felt, and even if felt it
  need not be consciously felt. The trigger for
  the unconscious background emotion may well not
  be traceable consciously. By the time the brain
  has noticed the autonomic changes the trigger
  will be long gone. This makes an exercise like
  collapsing anchors very useful.

76
Subjective well being1

• 1 Kahneman D Diener E Schwarz N (1999)
  Well-being the foundations of hedonic psychology
  Russel Sage (New York) Ch 4 Reports of subjective
  well-beingjudgemental processes and their
  methodological implications. Norbert Schwarz and
  Fritz Strack

• SWB feelings of happiness marks out of ten
• Based on the comparison of present situation (the
  target) to another situation (the standard) which
  may be past, future, or counterfactuals (what
  might have been)
• Depressed people compare target to
  counterfactuals, decreasing SWB
• Relevant to mental training in terms of memories
  of the future although this is in fact
  experiencing the future as the present (the
  target) and comparing it to the present(the
  standard which becomes the past)) hence
  increasing SWB which allows actual better use of
  processing to achieve the goal.

77
Subjective well being

• If we call to mind a past event with strong
  positive affect this affect will override the
  comparison effect this is an assimilation effect.
• Question order may affect assessments of SWB
• Certain factors increase mood valency from past
  events.
• Schwarz and Strack 1999

78
Valence of Event
79
Subjective well being

• In summary, the best way of increasing positive
  mood states is with detailed description of how
  something happened that was positive. In
  recalling a stressful event we concentrate on the
  happy feelings at the outcome.
• This can then be fixed with a trigger or an
  anchor.
• Fixation of positive mood state automatically
  triggers effective processing from dopamine
  release in the pre frontal cortex.
• Once we are aware of the source of our positive
  mood state it is discounted, non-conscious is
  best (schwarz 1983)
• Non conscious processing most efficient for
  paralell processing. Use of verbal reasoning
  reduces performance.

80
Important

• Vivid recall of how an event proceeded is an
  effective way of fixing positive mood states
  which may then provide the ability to recall
  successful problem solution.

81
Depression PTSD Chris Brewin

• Dissociation, Encoding, thought suppression and
  working memory capacity

82
Demonstration
83
Intrusive Thoughts
1Intrusive Autobiographical memories in
depression and post-traumatic stress disorder
Brewin C (1998) applied cognitive psychology vol.
12 359-370

• Brewin examined the correlates of depression and
  PTSD. He found that there were certain
  similarities between the conditions. He examined
  large numbers of depressed people.
• He particularly looked at research into intrusive
  autobiographical memories.
• Both depressed and PTSD patients reported these,
  the difference was that PTSD patients had greater
  evidence of dissociation at the time of the
  incidents.

84
Normal Population.
1Brewin C Christodoulides J and Hutchison G
(1996) Intrusive thoughts and memories in a
nonclinical sample. Cognition and Emotion 10
107-112

• In non-clinical populations intrusive thoughts
  and memories both common, thoughts commoner.1
• When thoughts elicited first, they were more
  unpleasant. Thoughts associated with fear,
  memories with sadness or happiness.1
• In normal population involuntary memories are
  usually positive.2
• Ease of retrieval based on the intensity of the
  experience and its life impact.3

2Bernetsen D, (1996) Involuntary
autobiographical memories Applied Cognitive
Psychology 10 435-454
3 Pillerner D, Goldsmith J, Panter A, White S
(1988) Very Long Term Memories in the first year
of college Journal of Experimental
PsychologyLearning, Memory and Cognition 14
709-715
85
Post Traumatic Stress Disorder
1 Koss M, Tromp S, Tharan M (1995) Traumatic
memories empirical foundations, forensic and
clinical implications Clinical Psychology
Science and Practice 2 111-132

• Intrusive memories are characterised by even
  greater clarity and persistence accompanied by
  high levels of emotional arousal containing
  strong sensory and perceptual features.
• Memory for central facts is accurate and
  persistent, memory for peripheral details is less
  consistent or impaired.1
• Differ from non-clinical samples in that they
  often consist of parts and fragments of events,
  experienced as reliving the event in the present
  moment, and content cannot be deliberately
  retrieved, indeed is actively excluded.
• These observations led to Brewin et als dual
  representation theory of PTSD.

86
1 Brewin C, Phillips E, Carroll F, Tata P (1996)
Intrusive memories in depression Psychological
Medicine 26 1271-1276
2 Brewin et al in press at 2002

• Mixed sex sample of depressed patients 27/31
  reported intrusive memories for past life events
  associated with depression, 2-3 memories per week
  with high levels of intrusion and avoidance for
  each.1
• A stringent test of this hypothesis that
  depression n leads to an increase in the
  accessibility of specific autobiographical
  memories would involve comparing depressed and
  non-depressed exposed to the same stress. This
  was done with patients diagnosed with cancer.
  Depression level throughout was closely matched
  with level of intrusive thoughts.2
• Overgenerality is the symptom most closely
  predictive of future depression. 3
• It is proposed that overgeneral is related to
  deficits in problem solving because patients
  cannot retrieve appropriate memories of
  successful problem solution.4
• Overgeneral memory related to reported chilhood
  sexual abuse and to more avoidance as measured by
  IES5

3 Brittlebank A, Scott J, Williams J Ferrier I
(1993) Autobiographical memory in depression
State or Trait marker British Journal of
Psychiatry 162 118-121
4 Williams J (1992) Autobiographical memory and
emotional disorders in S A Christensen (Ed)
Handbook of emotion and memory 451-477 Hillsdale
N.JErlbaum
5 Kuyken W, Brewin C (1994) Intrusive memories
of childhood abuse during depressive episodes
Behaviour research and therapy 32 525-591
87

• 54 depressed women 35 reported criteria for
  childhood physical or sexual abuse. 30 had
  intrusive memories of abuse related incidents in
  the previous week.1

88

• Although only correlational these studies raise
  the possibility that patients attempts to avoid
  intrusive autobiographical memories are causally
  implicated in their overgeneral memory problem.
• From all these studies and others Brewin
  concluded that there were few differences between
  controls depressed patients and PTSD patients
  other than the severity of their intrusion and
  avoidance the only real difference being that
  dissociative out-of-body responses are more
  common with PTSD. He refutes Becks idea of
  generalised negative schema as the data is much
  more about avoidance.

89
Dual Memory Theory

• Brewin identifies specific differences between
  memories that are part of an autobiographical
  narrative, so called Verbally Accessible Memory
  (VAM) and memories that are fragmented with
  flashbacks only under limited strategic control.
  Patients have a limited ability to avoid these by
  trying to avoid salient clues called
  Situationally Accessible memory (SAM)
• SAM comes from extensive lower level perceptual
  processing of the scene and the patients response
  to it.
• The purpose of the flashback is to try to
  transfer the experience into declarative memory
  usually with limited success.

90
(No Transcript)
91
Thought Suppression, Intelligence , and working
memory capacity CR Brewin A BeatonBehaviour
Research and Therapy 40 (2002) 923-930

• Found that the ability of normal people to
  suppress memories at will was related to their
  working memory capacity.
• This was logical as concentration is a factor
  involved in not thinking about extraneous
  factors.
• This fits with the DLPFC inhibiting the amygdala.
  
• This led to the paper The Effect of encoding on
  intrusive memories for a stressful film.(2001)
  Brewin C and Saunders J
• In this study they attempted to dissociate people
  watching a stressful film by giving them a dual
  task condition in which they performed a tapping
  test.
• They predicted that those doing the tapping test
  would suffer more intrusive memories after the
  film.
• Result, however was that the reverse happened and
  they suffered less intrusion with lower IES
  scores. Brewin struggled to explain this at the
  time, but subsequent ideas have seen the knitting
  ladies at the guillotine may have been doing the
  same.

92
Important

• A tapping task engaging working memory will
  reduce the IES scale after a stressful film.
• Excessive amygdala activity will prevent VAM by
  inhibiting the function of the hippocampus and
  the PFC.
• The amygdala is inhibited by the DLPFC