confabulatory hypermnesia

Neurophilosophy is all abuzz with the discovery of a new neurological disorder known as confabulatory hypermnesia, also known as severe false memory syndrome. The gist of it is that the one individual they've come across who is afflicted with it exhibits a surprisingly accurate detail of memories he's completely made up. While confabulatory hypermnesia resembles spontaneous confabulation, a disorder characterized by making up accounts that may be fantastical in nature, the defining feature of confabulatory hypermnesia is that this individual provides answers to questions that would normally be answered by both normals and spontaneous confabulators with "I don't know." (*Note: Oliver Sacks had a fantastic account of spontaneous confabulation in The Man Who Mistook HIs Wife for a Hat*)

For example:

3.3.1. Personal Semantic Memory
Q. ‘‘What is your brother’s job?
A. ‘‘Re´my is an artist. He works in variety shows.’’ LM confuses
his brother with his son (Patrik) who actually works as
an artist in variety shows.

3.3.7. Semantic Plans
Q. ‘‘What do you think will be the most important advancements
in the exploration of space in the next 10 years?’’
A. ‘‘We will land on the Moon and see if somebody lived
there, if it is habitable.’’

3.3.10. ‘‘I don’t know’’ Episodic
Q. ‘‘Do you remember what you had for dinner on Tuesday
two weeks ago?’’
R. ‘‘Steak with French fries.’’
Q. ‘‘Do you remember what you were wearing on the first
day of summer in 1979?’’
R. ‘‘A short and a T-shirt.’’
Q. ‘‘Do you remember what you did on March 13, 1985?’’
A. ‘‘We spent the day at the Senart Forest’’ (a place where
LM used to go often with his family).

The curious thing about confabulatory hypermnesia is that there is no discernible organic lesion associated with it. Spontaneous confabulation and amnesia are often products of Wernicke-Korsakoff's Syndrome caused by severe alcoholism. L.M. was an alcoholic and exhibits the typical global tissue atrophy characteristic of alcoholics, but there is no defined lesion that separates the confabulatory hypermnesic from spontaneous confabulators.

The authors, however, propose an extremely interesting theory as to why this comes about. Before I go into it, Dalla Barbara proposed the Memory, Consciousness and Temporality Theory (MCTT), which suggests that the CNS does not just passively receive incoming information from the outside world, but actually has modes for understanding the object being perceived. In consciousness there are two very important modes that are central to understanding the object as it is rendered by the sensorium: Knowing Consciousness (KC - "the mode of addressing the object in order to know it") and Temporal Consciousness (TC - "temporalising the object according to past, present or future structures of temporality"). When consciousness processes the information, the object then has a Uniqueness (its determination) and a Multiplicity (its indetermination). Dalla Barbara and Decaix give an example:

"This pen on the desk is both a pen and the pen. In the first case it is an undetermined pen, something that belongs to the category of ‘‘pens’’, an object that I recognize and use appropriately because I recognize it. On the contrary, in the second case ‘‘the pen’’ is a determined object, is exactly this pen in front of me, the pen I bought yesterday and that I will be using tomorrow. So, the pen reveals a uniqueness and a multiplicity, the multiplicity of being a pen and not a different object of the object in front of me, the uniqueness of being precisely this pen and not another pen."

Visualized, it appears as follows:



What is hypothesized to happen in confabulatory hypermnesia is that TC is cut off from being able to perceive if an item holds a Uniqueness, so that only the KC is able to determine if an object has a Uniqueness. Unfortunately, this makes it so that pretty much any Multiplicity is deemed to be an appropriate memory, therefore memories are often born more out of association than of actuality. "What TC does instead in this condition is to address Multiplicity of the object as Uniqueness, so that the result is that not only unique personal episodes, but also habits or personal semantic information are considered in a personal temporal framework." "Most of his confabulations to ‘I don’t know’’ Episodic questions reflect the retrieval of personal habits or semantic information rather than retrieval of imagined events: the Senart Forest is a place where he used to go often with his family, steak and French fries are a very common meal in France, in summer many people wear shorts and T-shirts."

Visually:



Fantastic stuff, no? It crosses the domains of frontal executive functioning and memory in both episodic and semantic domains, combining them into a real questioning of the nature of our consciousness and our neurological integrity! There are so many questions that these authors suggest that are really burning questions into the study of memory and ultimately the study of how we perceive the world, like what delineates the boundaries of TC, is there a possibility for an episodic and semantic double dissociation in confabulatory hypermnesia, and what are the cognitive and neurological correlates of this disorder?

The fact that we're continuing to unveil new and undiscovered syndromes just goes to show that we are only barely beginning to understand the complexities of the CNS. How I love these uncharted lands!

You can read the paper here.

clinic pt. 3; of mice and of men

A subarachnoid hemorrhage patient came in today, the first I've ever encountered actually. Subarachnoid hemorrhages are bleeds occuring under the second layer, the arachnoid mater, covering the brain. It's funny because you often think that right below your skull is just your brain, shining and glistening, but that's not true, it's protected by three layers:



Skull
-----
Dura mater (tough, leathery)
-----
Arachnoid mater (thin, webby)
-----
Pia mater (v. thin, attached to brain)

Subarachnoid hemorrhages are interesting in that when bleeding occurs under this layer, it tends to bleed in a way that covers the whole brain rather than to bleeding just into one area and creating a pool of blood. Postmortem patients that had subarachnoid bleeds have brains that are all red because the layer allows the blood to spread diffusely through the cerebrospinal fluid. Patient had a CT which allows for confirmation of the bleed (CT scans allow blood to show up very clearly as being whiter - a subarachnoid bleed makes the whole brain look blurry), and then came to our unit for an angio just to confirm the source of the bleed. It was an aneurysm, much like this case:



We also had something I haven't seen before, which was a T9 facet joint injection. Basically this means that you stick a needle with a mixture of two medications (Marcaine - an anesthetic that acts on short term, Depo-medrol - a steroid that promotes healing in the long term) into the spaces between injured spinal area. I found it strange that the patient is lying there with a needle sticking out of his back as if he had just been stabbed.



After work, I got to go over to Dr. Kar's lab and shadow one of the research students. Little did I know that this was what I got to witness:



There were a bunch of mice in this cage looking really cute, which is saying a lot because I hate mice or rats or any rodent, really. I go, "Cute!" and she says, "No, don't get attached." She then picks up a mouse and puts it in this jar of anesthetic that promptly knocks it out. Then she pulls it out and stretches it out on its back like in the picture, and pours anesthetic down its throat, just in case. Using a pair of scissors, she slices open the stomach, and its entrails come pouring out. She carefully removes the ovaries, then, quite surgically, snips off the mouse's head.

I was fascinated because dissections are really neat, but at the same time, if it was me holding those scissors, I'm not really even sure I could do it. And even if I did, is that a part of me, morally, that is dying? Even though the mouse is completely anesthetized and probably feels no pain, it still begs the question that there is no real humane way to kill anything. Killing is killing, and I'm not sure where I stand on the issue. Hopefully I won't have to do any mice dissections?

Anyways, she then took the ovaries, put them in a dish, and then carefully opened them up with a scalpel. She removed the tiny mice growing in the ovaries, cut their heads off, then transferred them to another dish. She then cut their heads open to reveal their brains, then took them over to the microscope so she could dissect out the hippocampus in order to do neuronal cell cultures.

What a day.

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In other news, the sleeper movie of this year, watch it:



Kate Beckinsale, Matt Dillon, David Schwimmer, Angela Bassett in a courtroom thriller about a reporter who has revealed a CIA agent. She opposes the federal court when they ask her to reveal the name of her source, and she refuses, which is essentially treason. As a result, she is jailed.

The movie is slow, but amazing on many levels. There's a speech delivered about 4/5ths through the movie by her attorney that is one of the best speeches I've heard in a movie, ever. There's also the mother of all twist endings that is guaranteed to floor. If you're heading to the rental place and are looking for something, better to watch this, it definitely beats Twilight. I'm so surprised movies like this go straight-to-DVD when they deserve to be on the podium.

Enjoy your long weekend.

neuroethics

From my long disappearance from the interwebs realm, I learned a lot about neurosurgery. I learned that the frontal lobotomy still taints the name of neurosurgery to this day, which is kind of why the term "psychosurgery" isn't used anymore (surgery to alter behavior rather than surgery to alter a dysfunctional brain). A brain scan of a Freeman-Watts frontal lobotomy (note the degeneration of frontal tissue) and a well-known case of a 12-year old receiving the rather crude "ice pick" transorbital frontal lobotomy:




The frontal lobotomy has the rather disgusting history of being blown out of proportion as one of those cure-alls for psychiatric patients. Moniz invented the procedure and squeezed a Nobel out of it, but never intended this technique to be used like Freeman & Watts adopted it for, which was essentially to slice and dice the white matter connections (actually in the end they just cut anything in the way) in the frontal lobes, strongly affecting many structures including the limbic system. Essentially, whether you were suffering from schizophrenia or your mom just found you intolerable (like that 12-year old), you'd be recommended for a frontal lobotomy that would change your personality and emotionally blunt you forever.

As a result, both the general public and clinicians are hesitant to give our neurosurgery, and it is generally saved as a last-resort measure with intensive screening that goes on prior to approval. It's funny though because in neurology, many clinicians are extremely hesitant about giving a psychiatric patient a neurosurgical intervention - for them they see a psychiatric illness as a disease state of the mind, and not of the brain. Psychiatrists, on the other hand, are glad to recommend for surgery, knowing full well that these disorders are biologically based. Perhaps this is why neurosurgery for somatic disorders such as Parkinson's Disease are rather ho-hum, while if you say to someone you can get surgery to cure your OCD, it might come as more of a surprise.

So then I ask, what is the personality? Is all neurosurgery psychosurgery? I read this paper by Walter Glannon (2006) who posed, "for the patients who experience significant memory loss or personality change aas a result of the procedure, the cure may come at the cost of their identities, their selves. In these metaphysical terms, the cure may seem worse than the disease." These procedures often come with frontal disinhibition, minor personality alterations - some are transient, some are persistent sequelae. Is any neurosurgery appropriate, when we are effectively changing who someone is? Or do the benefits of neurosurgery outweigh the risk, that even though a person may be different at least they get to live a semi-normal life free of psychiatric illness?

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Anyways, if you'd like to read my paper on 'Theoretical foundations underlying neurosurgical interventions for the treatment of intractable OCD', you can find it >here. Don't worry, I won't blame you if you don't read it.

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Glannon, W. (2006) Neuroethics. Bioethics, 20(1), p. 37-52.