Deleting Unwanted Memories: Neural Mechanisms of Deliberate Recall Suppression

“Cervell i Conducta”.Consciousness and Executive function Topics.

School of Medicine. Autonomous University of Barcelona.

Dept. Of Psychiatry. Unit of Medical Psychology. Bellaterra.

Third Course. Vall d’Hebrón Hospital and Mar Hospital. Barcelona.

Suppression vs. Intrusion of Traumatic Memories: Revisiting Freud through Neuroimaging?

Adolf Tobeña

Unit of Medical Psychology

Dept. of Psychiatry and Forensic Medicine. School of Medicine.

Autonomous University of Barcelona.

08193-Bellaterra. Spain.

Suppression vs. Intrusion of Traumatic Memories

Freudian repression consists in efficient suppressing of traces of images, thoughts and actions which are

disturbing or just unwanted, making intentional access to them difficult or impossible.

The burial of unwanted memories - putting them out of conscious scrutinizing/retrieval reach - is a central

tenet of prevalent cognition models proposing different degrees of accessibility to stored recollections

Suppression vs. Intrusion of Traumatic Memories

Learning to Forget

Science, 2 April 2004, 304, 34-36.

Cognitive Neuroscience: Repression revisited

Nature, 15 March 2004, 319-320.

Suppressing unwanted memories by executive control MICHAEL C. ANDERSON AND COLLIN GREEN

Department of Psychology, University of Oregon, Eugene, Oregon 97403-1227, USA

Abstract:

Freud proposed that unwanted memories can be forgotten by pushing them into the unconscious, a process called repression. The existence of repression has remained controversial for more than a century, in part because of its strong coupling with trauma, and the ethical and practical difficulties of studying such processes in controlled experiments. However, behavioral and neurobiological research on memory and attention shows that people have executive control processes directed at minimizing perceptual distraction, overcoming interference during short and long-term memory tasks and stopping strong habitual responses to stimuli.

Nature 410, 366 - 369 (15 March 2001).

Suppressing unwanted memories by executive control

Nature 410, 366 - 369 (15 March 2001).

Here we show that these mechanisms can be recruited to prevent unwanted declarative memories from entering awareness, and that this cognitive act has enduring consequences for the rejected memories. When people encounter cues that remind them of an unwanted memory and they consistently try to prevent awareness of it, the later recall of the rejected memory becomes more difficult. The forgetting increases with the number of times the memory is avoided, resists incentives for accurate recall and is caused by processes that suppress the memory itself. These results show that executive control processes not uniquely tied to trauma may provide a viable model for repression.

Abstract (Following):

Oregon GO-NO GO Procedure to study Memory Suppression

A. Acquisition through repetition of 40 pairs of associated-words

home - kid rank - key ordeal - roach nest - slim ......... Till 50% of correct retrieval performance

B. Recall Suppression through “Think-Not think” instructions INDUCTOR - X home - (kid) “think and say aloud!” rank - (key) “ ordeal - ( ) NOT THINK AT ALL!!

Oregon GO-NO GO Procedure to study Memory Suppression

INDUCTOR X

Up to complete 377 Think-Not Think trials, with 15 associations to suppress.

Interstimulus interval: 400 ms Errors followed by an intense “beep” 67% of trials required responsesConditions: 0 (Baseline) vs. 1, 8, 16 Repetitions of Think-

Not Think essays Inductors: Trained (Same) Cues vs. Independent Cues

Oregon GO-NO GO Procedure to study Memory Suppression

C. Recall test:

inductor X

Same Cue home (kid)

Same cue ordeal ( )

Independent cue Insect r........

For the different pairs through the 0, 1, 8, 16 Repetitions of Think-Not Think Essays.

Suppressing unwanted memories by executive control

Final recall for respond and suppression items as a function of the number of repetitions for the same-probe (SP) and independent-probe (IP) tests. a, b, Experiment 1; c, d, experiment 2; e, f, experiment 3; g, averaged across experiments. Note the negative slope for recall of the suppressed item, indicating increasing inhibition.

Exp.1, general conditions as outlined. Exp. 2, paying the Ss. for efficient performance. Exp. 3, telling Ss. that instructions to suppress tipycally enhance memory.

Suppressing unwanted memories by executive control

Three Mechanisms to explain impaired recall. 1. Associative Interference. 2:. Unlearning 3. Suppression. Testing the target with an independent cue circumvents 1 and 2.

Suppressing unwanted memories by executive control

Final recall of withhold and respond items as a function of the number of repetitions. a, Performance in the same test probe (SP) condition. b, Performance in the independent probe condition (IP). In both conditions, withhold item performance (don’t think-don’t say ) does not decrease

with repetition.

Neural Systems Underlying the Suppression of Unwanted Memories

Michael C. Anderson, Kevin N. Ochsner, Brice Kuhl, Jeffrey Cooper, Elaine Robertson, Susan W. Gabrieli, Gary H. Glover, John D. E. Gabrieli

Over a century ago, Freud proposed that unwanted memories can be excluded from awareness, a process called repression. It is unknown, however, how repression occurs in the brain. We used functional magnetic resonance imaging to identify the neural systems involved in keeping unwanted memories out of awareness. Controlling unwanted memories was associated with increased dorsolateral prefrontal activation, reduced hippocampal activation, and impaired retention of those memories. Both prefrontal cortical and right hippocampal activations predicted the magnitude of forgetting. These results confirm the existence of an active forgetting process and establish a neurobiological model for guiding inquiry into motivated forgetting.

Department of Psychology, University of Oregon, Eugene and Departments of Psychology and Radiology, Stanford University. Science, 303, 232-5, 2004

Neural Systems Underlying the Suppression of Unwanted Memories

Science, 303, 232-5, 2004

Procedure:

Acquisition Training of 36 Word Pairs, till at least 50% correct performance (Mean: 73,8%).

Think-Not think Exercises while fMRI Scanning: - 384 trials, 4 sec. / inductor. - 16 repetitions of inductors/block, 45 sec. rest between blocks. - fMRI scans: 13 min. during “suppression”, 13 min. “retention”.

Recall Test

Neural Systems Underlying the Suppression of Unwanted Memories

Science, 303, 232-5, 2004

Individual differences in Suppression: Between 8-32% in both Conditions

Individual Differences in Inhibition efficiency!!: between 8 % facilitation to 32% suppression, in both conditions!!

Suppression of Unwanted MemoriesfMRi activations and Desactivations

Science, 303, 232-5, 2004

Blue: Deactivation during “suppress” condition. Bilateral hippocampus.

Yellow; Activation during “suppress” condition. Dorsolateral and Ventrolateral Prefrontal cortex. Pre-motor and supp. motor areas.

Suppression of Unwanted Memories: network of active/ inactive brain regions

Science, 303, 232-5, 2004

Active regions: Dorsolateral and Ventrolateral Prefrontal Areas Anterior Cingulate Supplementary motor and premotor areas Intraparietal sulcus and right putamen

Inactive regions: Bilateral hippocampus Frontopollar cortex Posterior Insullae Bilateral cuneus

Active Suppression of Unwanted Memories: Dorsolateral Prefrontal Cortex Areas at work

Science, 303, 232-5, 2004

A: Relation of Suppression activation to memory inhibition: white arrows highlight DLPFC regions showing active suppression

B and C: Memory inhibition effects depending on DLPFC activation and interaction with probes.

Suppression of Unwanted Memories: Summatory interplay between right hippocampus and DLPFC

Science, 303, 232-5, 2004

Suppression items: Sf (forgotten) Sr (remembered).

Neural Systems Underlying the Suppression of Unwanted Memories

Science, 303, 232-5, 2004

• Although controlling traumatic memories is difficult, intrusive reminding of trauma and the intensity of the associated emotional response to trauma related stimuli diminish over time for most people. This remission may reflect in part the cumulative inhibitory effects of the voluntary suppression mechanism revealed here, perhaps in tandem with systems involved in the extinction of conditioned emotional responses or in the cognitive reappraisal of traumatic memories.

• Whether suppression can produce complete and lasting amnesia for an unwanted memory remains unknown. However, this work confirms the existence of an active process by which people can prevent awareness of an unwanted past experience and specifies the neural systems that underlie it. This process causes forgetting. Thus, the current findings provide the first neurobiological model of the voluntary form of repression proposed by Freud, a model that integrates this otherwise controversial proposal with widely accepted and fundamental mechanisms for controlling behavior.

Oregon Conclusions:

Suppression vs. Intrusion of Traumatic Memories: Revisiting Freud through Neuroimaging?

Oregon experiments have demonstrated that prefrontal executive systems can effectively weaken unwanted declarative memories. Recall reductions are, however, around 15% at most, which is in striking contrast with the potency of passive forgetting plus interference effects.

In Psychopathology the reverse phenomenon is much more crucial and challenging: reverberant intrusions of painful memories despite deliberate and effortful attempts to get rid of them.

A good deal of Psychotherapy Techniques have just this goal!!...The

contrary of Freudian repression indeed!!!!.

Executive Control to suppress traumatic memories?: A Conjecture

- Traumatic Memories linked to social emotions: Shame, guilt, embarrasment, contempt....,

Swift executive deleting leading to Adaptive Self-deception !!!

- Traumatic Memories linked to primary emotions: Fear, rage, sadness, defeat, humiliation...

Intrusive and reverberant maladaptations due to higher

resistance to voluntary deleting systems ??? Attention to Individual differences!!

Suppression of traumatic memories: Deleting-Enhanced properties of Psychotherapies or Drugs

Extinction of emotional learned responsesCognitive reappraisal of painful/toxic recollectionsOther Behavioral/Cognitive techniques...

- Recruiting additional neural deleting mechanisms (medial prefrontal cortex in fear extinction, for instance)

- Drug boosters of fear extinction: D-cycloserine, propanolol, yohimbine, cannabinoïds

- Transcranial magnetic stimulation suppressing intrusive recollection in postraumatic stress patients....

Limits to emotional forgetting???

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding:

A study with the Roman rat strains

Behavioural Processes, Volume 66, Issue 1 , 30 April 2004, Pages 63-72

Raul Aguilar, Luis Gil , Alberto Fernández-Teruel and Adolf

Tobeña

Medical Psychology Unit, Department of Psychiatry and Forensic Medicine, School of Medicine, Institute of Neurosciences, Autonomous University of

Barcelona, Bellaterra, Barcelona 08193, Spain

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding: a study with the Roman rats

Aguilar R et al (2004) Behavioural Processes, 66, 1, 63-72

• Abstract• In the present study, we evaluated the effects of extended exposure

procedures to contextual fear cues as a way of reducing intertrial responses (ITRs), a characteristic stereotyped behavior displayed in 2-way Shuttle Box avoidance overtraining. We used rat strains psychogenetically selected for efficient (Roman high-avoidance; RHA) versus poor 2-way Shuttle Box performance (Roman low-avoidance; RLA), the former being fearless/impulsive relative to the latter. Additionally, Sprague-Dawley (SD) rats were compared with RHAs to have a measure of the ITRs exhibited by another, non-selected group of animals. The main findings were that after extended exposure RHAs diminished their ITRs without affecting avoidance performance, although they emitted a pattern of ITRs somewhat excessive as compared with SDs. We concluded that three factors could influence the expression of ITRs in RHA rats: (1) the repetitive and stereotyped responding induced by 2-way Shuttle Box overtraining; (2) contextual fear conditioning; and (3) a genetic background associated with high impulsiveness.

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding: a study with the Roman rats

Aguilar R et al (2004) Behavioural Processes, 66, 1, 63-72

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding: a study with the Roman rats

Aguilar R et al (2004) Behavioural Processes, 66, 1, 63-72

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding: a study with the Roman rats

Aguilar R et al (2004) Behavioural Processes, 66, 1, 63-72

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding: a study with the Roman rats

Aguilar R et al (2004) Behavioural Processes, 66, 1, 63-72

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding: a study with the Roman rats

Aguilar R et al (2004) Behavioural Processes, 66, 1, 63-72

Genetically-based behavioral traits influence the effects of Shuttle Box avoidance overtraining and extinction upon intertrial responding: a study with the Roman rats

Aguilar R et al (2004) Behavioural Processes, 66, 1, 63-72

Suppression of traumatic memories: Deleting-Enhanced properties of Psychotherapies or Drugs

Extinction of emotional learned responsesCognitive reappraisal of painful/toxic recollectionsOther Behavioral/Cognitive techniques...

- Recruiting additional neural deleting mechanisms (medial prefrontal cortex in fear extinction, for instance)

- Drug boosters of fear extinction: D-cycloserine, propanolol, yohimbine, cannabinoïds

- Transcranial magnetic stimulation suppressing intrusive recollection in postraumatic stress patients....

Limits to emotional forgetting???