How the Brain Stores Traumatic Memories

Sagittal MRI slice of a brain with highlighting indicating location of the posterior cingulate cortex. The study cited found traumatic memories engaged this area, usually associated with narrative comprehension and autobiographical processing, like introspection and daydreaming.

A Conversation with Neuroscientist Daniela Schiller

Part One of a three-part interview. Read Parts Two and Three.

Does the brain encode traumatic memories differently than it does other memories? This question prompted a recent series of experiments by a group of researchers at Yale University and the Icahn School of Medicine at Mount Sinai. The publication of their breakthrough findings in Nature Neuroscience[1] in November generated news media headlines.[2] To learn more about these findings, I interviewed one of the authors of the study, Daniela Schiller, Professor of Neuroscience and Professor of Psychiatry at the Icahn School of Medicine at Mt. Sinai and Director of the Schiller Laboratory of Affective Neuroscience. In 2014, The New Yorker did an extensive profile[3] of Dr. Schiller’s achievements in memory research.

Dale Kushner: Is it accurate to say your goal is to untangle a traumatic memory from the strong emotion it evokes so that a person might be able to remember something traumatic but not feel its negative effect?

Daniela Schiller: Yes. That’s the ultimate goal. The way to go about it is to ask questions about how to understand the mechanism: how the brain forms emotional memories, how it maintains these memories. Are these memories malleable? Do they change over time? Under what conditions do you retrieve them, in what way? To prevent the malfunctioning of it or the negative impact of it in certain cases you try to understand the entire mechanism of it. How does it work in the brain before it goes awry? And then what might change that it has such a negative impact?

DK: Could you briefly describe what you’re looking at now and how that unfolds for you in the lab?

DS: Sure. Here you have two main approaches. One will be the very, very controlled way that you create some experience in the laboratory and then you test it. For fear or for emotional memory, we can use this basic process that is called classical or Pavlovian conditioning, where you take one stimulus and associate it with something negative. That stimulus that used to be neutral is now negative. This you can do in the lab. You just present something on the computer, and they can get a mild electric shock, or they can lose money, something negative. They then develop this emotional response to the stimulus because they know that something negative is going to happen. When you look at that in the FMRI (Functional Magnetic Resonance Imaging) scanner, you can see specific responses in the brain to that stimulus before and after learning, or in comparison to other such stimuli, or such cues.

Another approach is to investigate memories that the participants themselves bring. This is what we did in the research that was just published. The participants had been diagnosed with PTSD and they had their own real life traumatic memories and also sad memories. We reminded them of these memories while they were in the FMRI scanner, and we then looked at the brain. So, we found a way to analyze that very naturalistic experience and real-life memory. And of course, this is personal. In classical conditioning, everybody undergoes the same stimulus. All the participants look at a blue square paired with a shock. Then we’ll see in the entire group on average how the brain is reacting. With the PTSD group we see each and every individual brain reacting to the personal memory, but we still find commonalities. And these commonalities tell us what is different between traumatic memories and sad memories.

DK: That’s very interesting. So, the participants in the first group who have not had PTSD, you’ve induced some kind of shock so that you have a parameter of what an untraumatized person might experience when they are initially getting traumatized in the laboratory. Then you compare that to someone who comes to you with a history of trauma and look for the same things. Then you compare the responses and figure out how the brain is working in both cases. Is that accurate?

DS: Yes. What you’re describing is a challenge to the field because we really cannot induce trauma in the lab. What you have in the laboratory is a model, something that mimics aspects of trauma. With animals, you would do an animal model, an animal will undergo something negative, and then they will be afraid. In humans, you can do the same, but what you do in this case is you’re asking questions about basic learning and memory processes in the brain. And by understanding these processes, which are in the neurotypical, in the healthy realm, by understanding these, you assume that when these systems are impaired or you can envision or try to manipulate the impairments, then you can hypothesize what is happening in the traumatic state. In this case, it’s more like an extrapolation or an assumption that it would apply to trauma.

That’s why our last experiment was exactly to address that issue or those assumptions. Is it true that very simple emotional processes by way of exaggeration become traumatic, or is it a whole alternative process?  It can either be an extension or really a dissociation. It’s a challenge to study trauma in the lab.

DK: Yes. I bet. So, what are your findings on that question so far?

DS: My understanding now is that it’s really both. It depends on what you’re asking. You can see these basic processes in relation to emotional stimuli that are not a traumatic event. You could still see impairment in the aftermath of trauma because for example, people with PTSD would be more sensitive to negative information or some negative surprise or the way they compute and interact with emotional stimuli. You do see changes at the basic level. So that approach is very informative. In addition, when we look at the specific individual personal traumatic memory, we did see a difference between the traumatic memory and a sad memory. It wasn’t just more of an exaggeration of it, which in the brain you would see as more activation, more impact. It really looked like an alternative path of representation. This stayed virgin between the two memories. So, I think both are occurring at the same time. I hope that makes sense.

DK: Yes, it does. And it gives me a sense of what clinicians are dealing with and going to have to deal with. This research is going to be applicable and so crucial for coming generations.

Part two of this interview will follow in January.

[1] O. Perl, O. Duek, K. Kulkarni, C. Gordon, J. H. Krystal, I. Levy, I. Harpax-Rotem, D. Schiller, “Neural patterns differentiate traumatic from sad autobiographical memories in PTSD,Nature Neuroscience, 26, 2226-2236 (2023); Published November 30, 2023.

[2] Barry, Ellen, “Brain Study Suggests Traumatic Memories Are Processed as Present Experience,” The New York Times, November 30, 2023.

[3] Specter, Michael, “Partial Recall,” The New Yorker, May 12, 2014.

This post appeared in a slightly different form on Dale’s blog on Psychology Today. You can find all of Dale’s blog posts for Psychology Today at “Transcending the Past.”

If you found this post interesting, you may also want to read “Recognizing and Healing Inherited Trauma,” “The Things We Carry: How Our Ancestors’ Traumas May Influence Who We Are,” and “Diagnosing and Treating PTSD and Complex PTSD: It’s Not About ‘What’s Wrong With You?’”

 Keep up with everything Dale is doing by subscribing to her newsletter, Exploring the Unknown in Mind and Heart.



Revenge Is Rarely Sweet

The Fallen Angel (1847) (Detail) by Alexandre Cabanel (1823-1889)  for revenge blog post

 

Experimental research suggests revenge costs more than it delivers.

Revenge is a universal human instinct. Who hasn’t nursed fantasies of transforming into an all-powerful being—an avenging Batman or Black Widow? We seek to harm those who have humiliated, shamed, dominated, or oppressed us. When our rights are trampled, when an abuser inflicts wounds, when our self-image or our collective identity has been dishonored, we desire retaliation.

Revenge, retaliation, retribution—these words are not as interchangeable as they seem. The Latin root of revenge is vindicare, which is also the root of vindication. It’s interesting how the meaning of these words has evolved over time. Revenge typically involves the desire to inflict harm, suffering, or punishment in response to a perceived wrong and often includes strong emotions like anger or a desire for personal satisfaction. Vindication is now associated with clearing one’s name or proving one’s innocence. Retaliation seeks to address a perceived harm but does not necessarily involve inflicting harm in return. Retribution seeks to impose just penalties within a legal or moral framework.

In all its permutations, revenge aims to redress a perceived injury and punish the perpetrator. Ironically, revenge can also act as a deterrent in preventing further injury. In situations in which laws or government are weak and where gangs, militia groups, or bullies rule, the law of the jungle prevails: Be careful who you mess with, or else. (or, in less friendly terms, kill or be killed). The warning may suppress further violence but also reinforce an authoritarian or coercive regime.

Does personal revenge work? Does it restore justice? Is it cathartic? The answer from various disciplines suggests not. Behavioral studies indicate revenge does not grant the euphoria of satisfaction, but instead sets up cycles of rumination and ongoing distress.[1] The diaries of school shooters and mass murderers testify to the obsessive nature of revenge. Venting anger through the written word or social media does not seem to alleviate the impulse toward violence.

Fantasizing about revenge may be tremendously gratifying but psychologists observe that acting out revenge does not diminish feelings of animosity and can even prolong the avenger’s reaction to the original offense. Contrary to popular belief, revenge is rarely sweet! Nor does it automatically lead to catharsis or closure, but instead invites continued brooding and dissatisfaction. Increased rumination sets the stage for retribution and more cycles of aggression. Addressing this toll on the avenger, journalist Eric Jaffe writes: “The actual execution of revenge carries a bitter cost of time, emotional and physical energy, and even lives.” [2]

Some researchers have suggested that unacknowledged revenge, when the victim does not know the source of their suffering, is especially unsatisfying to the avenger. (You get beat up coming home from work. I want you to know this is happening to you because of what you said to my sister and that I am responsible for your pain.) Writing in the November 2010 issue of European Journal of Social Psychology, the authors, Mario Gollwitzer and his cohort, conclude that successful revenge is not merely about payback, but about delivering a message. “When the offender understood revenge as punishment, revenge led to satisfaction and deservingness among victims.”[3]

Who seeks revenge and why is shaped by our individual personalities and cultural heritage. Most of us do not succumb to acting out our revenge. Some people when slighted are not tempted to retaliate and instead move on. Scientists speculate we may have evolved an adaptive internal scale that weighs the costs of revenge against its benefits. In his book, Beyond Revenge: The Evolution of the Forgiveness Instinct, experimental psychologist Michael McCullough contends that we may have evolved a secondary system of forgiveness that enables people to suppress the desire for revenge in favor of forgiveness. This internal system supports forgiveness and allows for the repair of a relationship.[4]

In some cultures, a desire for revenge arises out of public shame, while in individualistic cultures like our own, vengeance is sought when we believe ourselves or our rights have been dismantled or ignored. In societies that value collective identity, revenge can be evoked in response to the mistreatment of someone in our tribe or group: dishonoring my brother dishonors me.

The moral argument often cited for revenge goes back to Exodus 21-23, which dictates reciprocal justice: “But if there is serious injury, you are to take life for life, eye for eye, tooth for tooth, hand for hand, foot for foot, burn for burn, wound for wound, bruise for bruise.”[5] It is often misinterpreted as a call for revenge, but the Biblical phrase puts limits on retaliation, one eye for one eye, not two eyes for one eye. Gandhi famously said, “An eye for an eye makes the whole world blind.”

Retribution can sound like a claim for justice but the problem is that everyone’s justice looks different. Revenge can signal to the original victim an end to their exploitation or abuse, but the result of seeking justice through revenge is often more destruction and death. Tease a bear out of a tree and it may come charging at you in self-defense, but self-defense is not revenge. Revenge has a bitter and spiteful aspect that intends the other to suffer. The British philosopher and statesman Francis Bacon said, “A man that studieth revenge keeps his own wounds green.” More recently, I heard a podcaster say, “Revenge is like drinking poison and expecting the other guy to die.”

If the instinct for revenge is automatic and universal, how do we control its destructive urge? As thinking animals with the capacity to evaluate our thoughts and imagine future consequences, we are free, unlike the bear, to objectively assess and regulate our behavior. We can discern behavioral patterns that are troublesome and disentangle from the motivating revenge stories we tell ourselves about ourselves and others. In each situation that inspires revenge, we can reevaluate our narrative and rewrite the ending. Perhaps we can ask ourselves, Instead of revenge, what would my forgiveness look like here? 

[1] Carlsmith, K. M., Wilson, T..D., & Gilbert, D. T. (2008) “The paradoxical consequences of revenge,” Journal of Personality and Social Psychology, 95(6), 1316-1324

[2] Jaffe, Eric, “The Complicated Psychology of Revenge,” Association for Psychological Science Observer, October 4, 2011

[3] Gollwitzer, M., Meder, M., and Schmitt, M., (2010) “What gives victims satisfaction when they seek revenge?” European Journal of Social Psychology, 41(3), 364-374.

[4] McCullough, Michael, Beyond Revenge: The Evolution of the Forgiveness Instinct (2008). Jossey-Bass.

[5] Exodus 23, The Bible, New International Version

This post appeared in a slightly different form on Dale’s blog on Psychology Today. You can find all of Dale’s blog posts for Psychology Today at “Transcending the Past.”

If you found this post interesting, you may also want to read “Four Principles of Survival My Characters Taught Me,” “The Fear of Abandonment: Missing Mothers and Fairy Tales,” and “Risks of Speaking Out: Coping with the Inequality of Power”

 Keep up with everything Dale is doing by subscribing to her newsletter, Exploring the Unknown in Mind and Heart.