A Fold in the Brain is Linked to Keeping Reality and Imagination Separate, Study Finds

By Valerie Ross | October 7, 2011 1:02 pm

What’s the News: One of memory’s big jobs is to keep straight what actually happened versus what we imagined: whether we said something out loud or to ourselves, whether we locked the door behind us or just thought about locking the door. That ability, a new study found, is linked to the presence of a small fold in the front of the brain, which some people have and others don’t—a finding that could help researchers better understand not only healthy memory, but disorders like schizophrenia in which the line between the real and the imagined is blurred.

Scans of a brain with a distinctive paracingulate sulcus (left, marked by arrow) and without one (right)

How the Heck:

  • The researchers looked at MRI brain scans of a large group of healthy adults. In particular, they were looking for the paracingulate sulcus (PCS), a fold near the front of the brain. There’s a lot of variability in the PCS: some people have quite distinctive folds, others have barely any. It’s in a part of the brain known to be important in keeping track of reality, which is why the researchers chose to study it. Of the 53 people selected for the study, some had this fold on both sides of their brain, some had it on one side, and some had no fold.
  • The participants saw some full well-known word pairs (“Jekyll and Hyde”) and some half pairs (“Jekyll and ?”). If they only saw half of a pair, they were asked to imagine the other half (“Hyde”). After each pair or half pair, either the participant or the experimenter said the whole pair aloud.
  • Once they’d seen all the pairs, the participants were asked two questions about each phrase: Did you see both words of the pair, or just one? And who said the phrase aloud, you or the experimenter?
  • People who didn’t have the fold on either side of their brains did worse on both questions—remembering if something was real or imagined, and remembering who’d done something—than people whose brains had the fold. But they felt as confident in their answers, meaning they didn’t realize they’d been mixing up internal and external events.

What’s the Context:

  • Poor reality monitoring—not clearly remembering whether something was real or imagined—could play a role in diseases such as schizophrenia. Schizophrenics often report hallucinations, like hearing a voice when no one’s speaking. “Difficulty distinguishing real from imagined information might be an explanation for such hallucinations. For example, the person might imagine the voice but misattribute it as being real,” explained lead researcher Jon Simons in a prepared statement.
  • Earlier studies have shown that people with schizophrenia frequently have smaller or no PCS, suggesting a lack of this brain structure—and the associated difficulties with reality monitoring—could play a role in the disease, Simons said.

Not So Fast: The study only shows that the PCS and reality monitoring are linked, not that the presence or absence of the PCS is what causes some people to be better than others at this sort of memory task. It could be that another factor in brain development causes both small PCS and poor reality monitoring, for instance.

The Future Holds: The research team is now planning to study whether these findings hold true for people suffering with schizophrenia, by looking at whether schizophrenics with little to no fold have more hallucinations that participants with a clear fold.

Reference: Marie Buda, Alex Fornito, Zara M. Bergström, and Jon S. Simons. “A Specific Brain Structural Basis for Individual Differences in Reality Monitoring.” Journal of Neuroscience, October 5, 2011. DOI: 10.1523/JNEUROSCI.3595-11.2011

Image: Journal of Neuroscience, Buda et al.




CATEGORIZED UNDER: Health & Medicine, Mind & Brain
  • Sharon Coburn

    I would love to know if anyone has observed any change in the fold while we are dreaming.

  • Pat Thompson

    The image on the right shows SWELLING (ie, infection) which has displaced areas of that brain, PREVENTING expected cross-sections of the scan to be revealed at specific locations. The endotoxins of chronic or congenital VD infections in the bonemarrow, blood, and connective tissue are neurotoxic and devastating to memory.

  • http://www.rlbrody.com Rachel

    Does the fold’s presence (or lack of a presence) have a relationship to creativity/imagination/visualization?

  • http://my.opera.com/rfhurley Rob Hurley

    I’m curious to know, not about the extreme case of schizophrenia, but rather about more quotidian “disorders”, people with selective memory, and people who are congenital liars. These affect society as a whole much more than readily identified psychological disorders such as schizophrenia.

  • Michael Berry

    Brain science is so fascinating. Our brains are the source of everything we perceive, believe, experience and conceive (no rhyming intended!) and yet we know relatively little about the inner workings of this fantastic, organic machine.

    I recently read On Intelligence by Jeff Hawkins and although a lot of the text was way over my head (it is neuroscience, after all), I experienced a lot of “Wow!” moments while reading his explanations and examples on why we think what we think and how we perceive our realities. It’s both impressive and humbling to discover that the majority of our actions are not actions at all but rather re-actions to patterns we don’t pay conscious attention to and have adapted to through countless past experiences with the world around us.

    It’s a very enlightening book which I recommend to just about everyone. Don’t let the subject matter scare you off–the book is very approachable even for the least intelligent readers (I include myself in this group…in relation to neuroscience, anyway).

  • Bob

    And yet we drug the hell out of it and shock it with EcT…

  • Paapa Pancho

    Is there any part of the brain that has not been associated with schizophrenia?

  • Montana

    “Of the 53 people selected for the study…” makes me shudder at their findings.

  • http://sciencenotes.wordpress.com/ Monado, FCD

    Now to see if conspiracy theorists have a small PCS or people with no interest in fiction have a large one. In fact, Conservative Authoritarian personalities have been identified as refusing to change their minds when confronted with contrary evidence that they are wrong: perhaps they mistake their confabulations for reality. It might also be interesting to candle the brains of a few hundred religious faithful vs. rational skeptics.

  • Geack

    @sharon –

    The fold is a permanent structure in the brain – no one is observing any changes in it at all. They’re studying whether it presence or absence has any impact on how our brains process information.

  • Bob

    Scizophrenia is thought to be caused by a virus. Does this virus change brain development?

  • http://clubneko.net/ nick

    @Monado, FCD: “candle the brains?” awesome.

    So the only thing separating me from a schizophrenic is because I believe the voices in my head are me thinking?

  • http://stardustchannel.com sratdust

    Re: Michael Berry

    Our brains are not “the source of everything we perceive”.. that’s a typical mistake.. we perceive things that are external. Your fold may not be very pronounced.

  • John A.

    I wonder if there will be studies looking into this structure in relation to a patient’s prognosis with Alzheimer’s or other forms of dementia. Would it possibly lend greater resistance to dementia, or is this structure in particular affected?

  • http://www.linkedin.com/in/debiprasadghosh Debiprasad Ghosh

    So, Like Blood Group, Now we have Brain Group.

    L – Fold in left brain
    R- Fold in Right brain
    LR- folds in both left and right brain
    O- No fold

    Fn Factor
    + interested in fiction
    – Not interested in fiction

    LR+ is preferred choice

  • http://www.jessicasachs.com jsnydersachs

    I love this format–your six headings are both priceless and practical!

  • Greg for President

    Interesting. Let’s say I’m a lawyer and I have to cross examine a witness that doesn’t seem credible. Can I bring in a MRI scanner to see if they have this fold? Without the fold, may I assume they likely don’t remember the actual events, they just made them up the events that could have happend.

  • Susan Durham

    I absolutely concur that sociopathic people re-create scenes that they perhaps disremember (not saying whether on purpose or not), rather than purposely making up stuff. This affects all of us MUCH more drastically than people who are hallucinating, particularly where the person is a testifying cop (not that ALL cops are sociopathic, but this may account for the profusion of “lies” that may really be re-creations from objective evidence)

  • http://hertzlinger.blogspot.com Joseph Hertzlinger

    What part of the brain is responsible for taking a study with a sample size of 53 seriously?

  • Joytem

    saw a sample of the brain today but could not find the main sulci…I want 2 know if this is a medical condition

  • Shootist

    So this makes me sane? I’ve been psychoanalyzed, with some improvement in behavior and thought. Where did that originate, and how did it improve me? Was the fold always there and just needed turning on, or did analysis create it? Interesting questions …


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