Neurophilosophy

What did you do on March 13th, 1985? People with hyperthymesia (which has been characterized only recently, and of which just a handful of cases have so far been reported) would likely provide a vivid account of what happened on that day. And if this particular date has personal significance for you – if, for example, it was your wedding day, or the birth date of one of your children – then you will probably remember it quite well. But for most of us, the answer to this question is likely to be “I don’t know”.

In the journal Cortex, researchers describe the case of a patient with severe memory loss who has a tendency to invent detailed and perfectly plausible false memories (confabulations) in response to questions to which most people would answer “I don’t know”, such as the one above. They have named this unusual condition confabulatory hypermnesia, and believe that theirs is the first study to document it. 

The patient, a 68-year-old patient known as LM, had a history of heavy drinking which lasted more than 30 years and stopped just 3 months before the study was carried out. He was referred to the memory clinic at the Charles Foix Hospital in Ivry-sur-Seine for a neuropsychological evaluation after he began to experience memory loss and disorientation in time and space. A brain scan showed mild degeneration throughout the cerebral cortex and he was diagnosed with Korsakoff’s Syndrome, a neurodegenerative condition which occurs as a result of vitamin B1 deficiency and is associated with long-term, chronic alcoholism.

Gianfranco Dalla Barba and Caroline Decaix asked LM a series of questions designed to evaluate the extent of his confabulations. The test contained 165 questions which required the retrieval of various kinds of information in each of 15 domains, including personal semantic memory (his age, date of birth, current address and marital status), episodic memory (autobiographical events), contemporary and historical semantic memory (knowledge of facts, news events and famous people) and episodic and semantic plans (or knowledge of events, both personal and otherwise, which are likely to take place in the next 10 years). The answers he provided were compared to to those of a healthy control participant and to information provided by his family and friends. LM was found to exhibit an unusual tendency to provide completely confabulated answers to questions in all of the domains tested.

For example, when asked about his brother’s job, he told the researchers that “Remy is an artist who works in variety shows”, confusing his brother with his son, who actually does work as an artist in variety shows; when asked “What month is it?”, he answered “The end of December”, when it was in fact April; to the question “What happened in May 1968?”, he responded with “It was the beginning of of the workmen’s revolution; the government opposed Africa”; when probed about what he thought would be the most important advance in space exploration in the next 10 years, he he replied “We will land on the Moon and…see if it is habitable”; and when asked to tell the researchers what he would be doing that evening, he presponded with “I’ll have dinner with my wife and then watch the television news”, despite the fact that he was hospitalized at the time, and that there was no television on his ward.

Most strikingly, LM confabulated plausible answers to questions about both his personal life and public events, which would normally elicit from most people an answer of “I don’t know”. When the researchers asked him “Who won the Palme d’Or at the Cannes Film Festival in 1980?” he replied “Fernandel”; when asked what he had for dinner on Tuesday two weeks ago, he answered “Steak with french fries”; and when asked “Do you remember what you did on March 13th, 1985?” he replied “We spent the day at the Senart Forest.”

LM thus has a “pure” amnesic syndrome, in that his impairment is not associated with other cognitive deficits which might interfere with memory function. He scored normally on short-term memory tests, and the evaluation revealed mild, diffuse neurodegeneration, rather than damage in a specific part of the brain. False memories are not uncommon in patients with Korsakoff’s syndrome – indeed the condition is also referred to as amnesic-confabulatory syndrome. However, the confabulations of such patients are sometimes extraordinary, bizarre and verging on being delusional. LM’s confabulations, on the other hand, were always plausible, and therefore quite unlike those reported in other Korsakoff’s patients.

Some researchers have argued that confabulation occurs as a result of errors in source monitoring and reality monitoring. The former is a process by which the reliability of information is evaluated; the latter refers to the ability to distinguish between information generated from the perception of real events and information conjured up by the imagination. But neither of these explanations can account for LM’s confabulations, as he did not mistake real events for imagined ones. He had often visited Senart Forest with his family, and steak and French fries is a very common meal in France, and therefore one which he is likely to have eaten many times in the past.

So how might LM’s amnesic syndrome arise? The authors explain it within the framework of the memory, consciousness and temporality theory. According to this theory, consciousness always relates to “something”, such as an object or event, and does not exist as a unitary dimension, but rather as a distinct set of “modes” for addressing the “thing” of which one is conscious of at any given moment. These modes include knowing consciousness and temporal consciousness, which describe, respectively, knowing the object of consciousness and placing it somewhere on the timeline of past, present and future.

For example, a pen is a pen and a meal is a meal, and each can be lumped together with others into the same category. But at a given moment, one  might be conscious of the pen sitting on a table, or of the meal that has just been eaten. Thus, every object or event which enters consciousness has both a multiplicity and a uniqueness. The authors suggest that LM may be unable to distinguish between these two properties. His temporal consciousness is  present, but working abnormally. It has become “expanded”, so that while he can retrieve information about personal events and habits, the particulars of a specific object of consciousness are applied to all the objects within that category, and they become confused with one another.

Related:


Dalla Barba, G., & Decaix, C. (2009). “Do you remember what you did on March 13, 1985?” A case study of confabulatory hypermnesia. Cortex 45: 566-574. DOI: 10.1016/j.cortex.2008.03.009.

Comments

  1. #1 Elizabeth Burns
    May 27, 2009

    My mother has this. You can contact me if you’d like more information. I’ve been told that it is due to damage to her frontal lobe and that she is unable to form “new” memories, thus she confabulates to make up for the gap. Your article gave me new insight as to the “expanded” temporal conciousness. Thank you for writing this!

  2. #2 Jeremy Low
    May 27, 2009

    Strangely, in 1985 in “The Man Who Mistook His Wife for a Hat” by Oliver Sacks, the same basic pathology is described by Oliver Sacks.

    Is this different or am I missing something?

  3. #3 stewart
    May 27, 2009

    I see a number of patients with confabulation after brain injury, but I haven’t asked them about specific dates. If the question is asked, I wonder if this tendency might be identified more often.
    There’s a good new book out on confabulation. The Confabulating Mind, by Armin Schnider (2008). It seems worth checking out, with a description of different types fo confabulation, and some theoretical reasons for each type.

  4. #4 Mike
    May 28, 2009

    I find confabulation really interesting. I’ve seen someone taking an SSRI who developed what I would call extremely mild confabulatory tendencies in addition to disinhibition. Perhaps they never said things that were outright untrue, but they would definitely run their mouth and say things without really thinking. I don’t think they were ever willfully trying to mislead, though. Perhaps the SSRI caused executive function deficits due to a reduction in mesocortical dopamine?.

    There’s a problem with executive functioning deficits that could confound this analysis. Sometimes people with these injuries tend to blurt out answers that may sound good, but they aren’t really thinking too hard about it. So is this a memory problem? Or is it just a matter of people just saying whatever first pops into their head?

    Also do you know anything about narcissistic personality disorder? Apparently they are prone to certain confabulations about their life history. Unfortunately some of the descriptions about this condition are prone to pop-psychological B.S. See here for example.
    http://samvak.tripod.com/narcissistconfabulation.html
    Considering people with narcissistic personality disorder may often lack empathy, that is indicative of executive function problems. So perhaps lack of activity in specific frontal brain regions causes them to have out of sync memories or skewed opinions of themselves that don’t match up with other people. Being able to properly “weigh” memories seems like something that is important.

  5. #5 stewart
    May 28, 2009

    Jeremy, the case presented by Oliver Sacks (‘The lost mariner’) had Korsakoff’s syndrome, true, with profound amnesia, but didn’t show the type of confabulation described here. Rather, he’s described as showing his old memories, without awareness that there is a many-year gap to the present. Other patients (and they are patients – they need a high degree of care) may show fantastic confabulations (like the patient who told me he commuted to the hospital every day by helicopter). This case is unusual in confabulating quite ordinary, plausible things. Perhaps other people do this, and we don’t notice becuase we’re looking for outlandish responses.

  6. #6 roxie
    May 30, 2009

    Just to say korsakov’s is associated with intensive binge drinking over a several month period as well as with chronic alcoholism.
    I used to nurse a man whose memory lasted for 2 minutes before reverting to a blank state.

  7. #7 BB
    June 3, 2009

    Just out of interest, in response to Mike:

    “I’ve seen someone taking an SSRI who developed what I would call extremely mild confabulatory tendencies in addition to disinhibition. Perhaps they never said things that were outright untrue, but they would definitely run their mouth and say things without really thinking. I don’t think they were ever willfully trying to mislead, though.”

    - when I was on SSRIs I had these tendencies, it was a bit like when you are a bit drunk and free-associating with a friend, which can get quite amusing, but I was doing it in inappropriate situations, not really realising I’d just said what I’d said. Caused a lot of social difficulties for me.

  8. #8 EP
    June 7, 2009

    BB – yeah I had something like that too when I was on an SSRI. I would go up to people and tell them what kind of animal they looked like. I specifically remember being in the middle of a discussion before a biology course and saying to a guy “You look like a llama.”

    Things like that.
    I’m glad I’m not on SSRIs anymore…

  9. #9 julia
    June 25, 2009

    On your previous website your article on memory had a quote from Frederick Bartlett,
    …One’s memory of an event reflects a blend of information contained in specific traces encoded at the time it occurred, plus inferences based on knowledge, expectation, beliefs, and attitudes derived from other sources.

    I have looked everywhere for this quote, can you tell me where to locate it please. Thanks

  10. #10 Mo
    June 25, 2009

    @julia: It’s probably from his classic book Remembering. Have you searched the Bartlett Archive?

  11. #11 Maria
    August 1, 2009

    I recently came across your blog and have been reading along. I thought I would leave my first comment. I don’t know what to say except that I have enjoyed reading. Nice blog. I will keep visiting this blog very often.

    Maria

    http://memory1gb.com

  12. #12 Socco
    August 11, 2011

    Ha pasado al foro y ha visto este tema. Permitan ayudarle?
    http://www.elcoru.com/
    Socco

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