In a Word - Confabulation

This episode continues an intermittent series called “In a Word.”  Past episodes have explored words like Akathisia, Dissociation, Perseveration, and even the difference between Impulsive and Compulsive.  This episode explores Confabulation, including some of the brain circuits involved, and what might differentiate confabulation from other kinds of false or implanted memories or delusions.

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References and readings (when available) are posted at the end of each episode transcript, located at psydactic.buzzsprout.com. All opinions expressed in this podcast are exclusively those of the person speaking and should not be confused with the opinions of anyone else. We reserve the right to be wrong. Nothing in this podcast should be treated as individual medical advice.

Transcript

Welcome to PsyDactic.  I am Dr. O’Leary and today is March 20, 2024. I am a 4th Year Psychiatry resident in the National Capital Region and this is a podcast about psychiatry and neuroscience.  I make this podcast myself, in my office, while my wife, kids, and dog are not being too loud in the background.  My staff consists of me, myself, and I, and while we often argue with each other, we don’t have an editorial staff or fact checkers to make sure that I don’t make obvious or avoidable mistakes.  I also need to inform you that all the opinions here are my own and do not necessarily represent the views of my residency, the Defense Health Agency, the US Army or…

Today I continue an intermittent series I have called “In a Word.”  Past episodes have explored words like Akathisia, Dissociation, Perseveration, and even the difference between Impulsive and Compulsive.  Today, I am going to explore Confabulation.

I first encountered what appeared to be obvious confabulation from a patient with Wernicke-Korsakoff syndrome.  He woke up in the hospital every day with a new explanation for how he had arrived.  For those who don’t know, Wernicke-Korsakoff is a condition that happens when the mamillary bodies in the brain are damaged due to a thiamine deficiency that is most often caused by long-term heavy alcohol use.   The mammillary bodies are slowly becoming better understood, but for a long time we have known that damage to them causes some degree of anterograde amnesia, which is a deficit in making new memories.  Damage to the mammillary bodies also impairs recall of already formed memories.  Interestingly, patients often don’t act as if they cannot remember details and appear to just freely make them up as they go.

There is a circuit in the brain called the Papez Circuit.  The hippocampus, which is well known for its role in memory, has a friend in the medial temporal lobe called the entorhinal cortex which itself is also a major memory hub.  The hippocampus and the entorhinal cortex play a game of telephone where they talk back and forth to each other.  The hippocampus then sends messages to the mammillary bodies through lines that travel in a loop around the fornix.  The mammillary bodies then call the anterior thalamus, who then calls the cingulate cortex.  The cingulate completes the loop by calling up the entorhinal cortex.  Like any game of one way telephone, if one of the players messes things up, what comes out the other end is something unexpected.  This loop is thought to play a major role in both spatial and episodic memory.  The mammillary bodies also appear to help out coordinating movements with the cerebellum, and also in learning reward seeking behaviors and recalling salient details of events and objects in the environment.

Confabulation has been described as quote “false memory” or quote “an honest lie.”  Patients appear to just fill in the blanks of their memory with whatever seems reasonable at the time.  There is no intent to deceive.  I don’t think it would be fair to merely call all false memories confabulations.  One could make them equivalent, but I feel like there is something special about confabulations.  One thing is that they are not really memories.  What I mean by that is that confabulated facts don’t always stick around.  They often evaporate quickly after the telling.  Someone with bilateral damage to their mammillary bodies will also likely have anterograde amnesia, so they won’t be making memories of the confabulated story they just told.  It may be that this was an easy story for them to tell, so they might tell it again, but not because they remember that they told it before.  Instead, when I use the term confabulation, I mean it as a fragile brain state that is the result of an attempt to make meaning out of current circumstances or to fill holes in actually remembered events.  Our memories are not connections with an ethereal unconscious outside of the brain.  They are merely recreated brain states that help us to learn and at times even explore the past so that we can learn later something that we didn’t learn at the time.

When the memory re-creation mechanisms malfunction, but still send a signal that a memory has been retrieved, then our past is no longer static.  It creates itself.  Apparently the ventromedial prefrontal cortex has the capacity to raise doubt about the truthiness of our memories and may allow us to experience uncertainty.  If the vmPFC is damaged, then we might lose a vital double-checking mechanism.  Our default mode network is particularly active when we are engaged in self-referential memory retrieval, so it makes sense that the vmPFC, which is part of the default mode network, would play a role in distinguishing between fact and fantasy.  Something has to, or else every thought we have would be mistaken for something real.

Besides the frequently ethereal nature of confabulated memories, they might also lack some of the emotionally salient features of real memories or false, implanted memories.  Especially when the mammillary bodies are damaged, these invented memories are often experienced as matters-of-fact and not associated with other memories or emotions with the same force that our more truthy autobiographical memories are.  They are like movies our brain is watching and then suddenly adopting as its own story.

False memories as opposed to confabulations are far more personal.  In my last episode, I discussed a forensic psychiatry case regarding how the courts have through time changed their opinions about culpability of adolescents and children for their crimes.  Other cases I discovered during my foray into forensics included cases of adults or parents who were accused of rape, sexual assault, or abuse by children or students because their therapists had insisted that their current psychiatric symptoms must have been due to some past trauma, and then suggested culprits, who of course happened to be important people in their lives.  After some time with these repressed-memory-recovering therapists, their patients appeared to find lost memories hidden in their unconscious. Many lives were irreparably altered when allegations of the recovered memories were brought to authorities and prosecuted.  Studies since then have confirmed over and over again that our memories are not static, but malleable and often highly suggestible.  Studies of witnesses of crimes, for example, have shown that targeted questioning can make a witness become certain of a memory of something that could not possibly have occurred.

Just google “memory suggestibility” and you will recover more examples than you could possibly read of false-memory phenomena (doot doo do do do).  This is a pressing problem now with the advent of the information superhighway and social media that can easy “suggest” to people explanations for events that they either experienced in person or through the media. These “suggestions' ' then create what appear to be clear evidential memories that are strongly associated with whatever a person's emotional state was at the moment that the explanation was suggested.  This is one of the foundations of conspiratorial, viral memes.

But let me get back to confabulation, which I am defining not merely as a false memory or a suggested memory, but as an immediate need to fill in blanks in the brain without the kind of salience that real or intentionally fabricated memories have.  I think that it is important to be precise about language and not let our words have broader meanings because as psychiatrists we should always be trying to get closer to explanatory models that have predictive power.  If we use the word confabulation for every kind of false memory, then we are not being precise about the mechanism by which that false memory was made.  Even if we don’t know for certain the neurological difference between an implanted or “suggested” memory, and one that was invented in the spur of the moment to help a person whose brain is not functioning normally make some kind of temporal sense of continuity, we can still know that these phenomena are likely different things until proven otherwise.

I think it is of primary importance to distinguish between the workings of a pathological brain and a normal brain that has been manipulated by the kinds of experience that could influence any normally functioning, suggestible brain.

There are many ways that our memory breaks down under very normal circumstances.  People often remember things out of order and propose mistaken causality, such as when someone suggests that they made a decision because of information that, in fact, they actually found out after their decision was already made.  Memories may place people at scenes where they were not or combine two separate events that have similar characteristics (like thinking two arguments happened during the same family event when they were in fact at different times).  People may have semantic recall problems when they are, for example, saying “Ronald Regan” when they actually meant “Richard Nixon.”  I would not call these things confabulation, because I want to preserve the word confabulation for pathological, impromptu, explanatory memory inventions that are likely not to be permanently recalled later as coherent memories or associated with other salient features, such as emotions or particularly meaningful settings.

I also would not call false memories or confabulations “delusions,” even if the patient insists on their truth.  I have not yet dealt fully with the word delusion, in a large part because I am still struggling with it, but I am convinced that a delusion is not merely a fixed false belief.  If that were the case, then suggested-and-implanted memories would be delusions, but I am sure that delusions (if I were to try to be more precise) are not part of the same pathological mechanism as false memories or confabulations.  I want this kind of precision because the most important thing is the pathophysiology and mechanism of whatever phenomena we are considering.  Pathophysiology determines the treatment and prognosis, so trying to focus my words in ways that more clearly and quickly communicate this kind of information is something that I should prioritize.

Thank you for tolerating my soap box today.  I hope that, even if you think I am wrong, that I helped you to consider confabulation in a way you might not have otherwise.

I am Dr. O’Leary and this has been an episode of Psydactic.

Wiggins A, Bunin JL. Confabulation. [Updated 2023 Aug 28]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK536961/

Peterson DC, Reddy V, Mayes DA. Neuroanatomy, Mammillary Bodies. [Updated 2023 Aug 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK537192/ 

Mendez MF, Fras IA. The false memory syndrome: experimental studies and comparison to confabulations. Med Hypotheses. 2011 Apr;76(4):492-6. doi: 10.1016/j.mehy.2010.11.033. Epub 2010 Dec 21. PMID: 21177042; PMCID: PMC3143501.

https://neuroscientificallychallenged.com/posts/know-your-brain-mammillary-bodies