Tuesday, August 21, 2007

Types of Brain Damage

One thing that is always a concern with brain tumors, and with the various forms of treatment, is the possibility of irreversible brain damage.

Physicians speak of the possibility of "mental deficits" due to the tumor invading or impinging on areas of the brain that govern important functions (memory, emotions, speech, vision, etc.) In some cases, there may be temporary deficits after surgery that eventually go away, or there may be permanent ones.

I was very pleased that when I woke up from the surgery I was "still me." I had my mental facilities intact, still remembered everyone, and still thought the same tired old jokes were funny that I did before the surgery.

Before the surgery, I met with a neuro-psychologist, who administered a series of tests to assess my pre-operative mental function. These tests mostly focused on memory. For example, she asked me to name all of the animals I could think of. Of course, having just returned from an African Safari, where I had the seizure that set this whole thing in motion, I tended to come up with African animal names: "Wildebeast, water buffalo, baboon, monkey, vulture, lion, cheetah, hyena, ...". I don't know if I got extra points for "exotic" animals or not.

Then another test went like this: She told me the sad story of Suzie Thomson of South Boston, who was a cook in a school cafeteria, and had 10 hungry children of her own. One day Suzie was out on State Street, and was mugged and robbed of $56. She went to the police station, and the officers were so moved by her story that they took up a collection among themselves to reimburse her for her losses.

The test consisted of her telling me this story, then another unrelated story (which I must admit I don't fully recall, but seemed to involve a young male driver out west in Texas or somewhere, who ran off the road into a ditch, and damaged his car).

She asked me to repeat the driver story, which was easy, since she had just told it to me. But then by surprise she told me to now tell her the Suzie Thomson story. It's hard to get back into a Boston frame of mind after thinking about the wide open highway in Texas!

Anyway, I did pretty well in recalling the details of the Suzie Thomson story, and it seemed that most points were given for recalling details. I remembered her last name because it is the same as that of the famous physicist Lord Thomson, who proposed the "jellium" model of the atom in the early days of atomic theory. And I've been to Boston many times, so I know just where State Street is. (Although the concept of Boston police taking up a collection from their own funds led to some mental dissonance...)

I wonder if the story had been about, say, "Hedda Jmnanovich of Vransk, Poland" if I would have done as well. I've never been to Poland, and can't think of any clever tricks to remember those names... I don't know any streets in any city in Poland.

Anyway, she told me overall I scored above the 99th percentile. As a Caltech academic, this meant a lot to me. At Caltech, we like the 99th percentile. If you are much below than in your high school class, you won't get in as a student. And if you're not at that level as a graduate student, no search committee will recommend you for an Assistant Professor position. So that sounded good to me.

We didn't do a post-operative test, but I don't feel like I'm in any lower percentile now than before.

But it was eye-opening to me to see how they typically measure mental function. It is essentially what we engineers would call "unit operations:" elementary operations, not reducible to simpler steps. For example, they are interested in measuring how fast you can pull words out of memory: "List as many words as you can in 30 seconds starting with the letter S, not including proper nouns". But there was no test concerning pulling the right words out of memory!

For example, an interesting and practical test would be: "Name your wife", or "name your oldest son". If your wife is "Mary" and you say "Sue", I could imagine that this mental deficit might have some very long-lasting and severe consequences. These are the memory tests that matter in the real world! Other practical tests might be "When is your anniversary?", "What is your wife's birthday?". For the record, these are deeply ingrained into my brain, tumor or no tumor.

And then there is the question of mental deficits in reasoning. I was told that the left temporal lobe was responsible for, among other things, integrating individual memories, or sensory input, into more complex ideas. So what really concerned me was that either due to the tumor, or to the surgery to remove it, I might come to find nothing wrong with the following nonsensical statements:
  1. One plus two equals five.

  2. The laws of thermodynamics may be revoked.

  3. A machine that takes in no work and transfers heat from a cold to a hot reservoir with no other effect on the environment is possible to build.

  4. The evidence presented by Colin Powell at the UN before the invasion of Iraq constituted proof that Saddam Hussein had or was building weapons of mass destruction.

  5. There was credible evidence of a link between Saddam Hussein and Al-Queda.

  6. George Bush is a good President.

  7. The profit motive is good for the US education and health care systems.

The mental deficit characterized by belief that the erroneous statements 4 through 7 are true I will call "republicanism", a very widespread affliction of the brain in the areas that govern logic and common sense. This mental disorder only a few years ago afflicted approximately 51% of the American voting public. I am happy to report that today the disorder (especially as measured by question 6) only afflicts about 1/3 of the voting public. It seems that this great success was not due to advances in neuroscience, but to the ability of the brain to identify patent absurdities, and reassess the premises that led to absurd conclusions, such as "Dick Cheney is a smart man who values the opinions of all, and would make a great President."

It is this sort of mental deficit that would really impact my life and career. For example, it would be mildly interesting to ask a question like: "List as many hyperbolic partial differential equations (PDEs) as you can in 30 seconds." But far more relevant would be "list an appropriate set of boundary and initial conditions for a hyperbolic PDE in 2 dimensions; repeat for parabolic and elliptic PDEs." I have to say that if I confused hyperbolic and elliptic PDEs (one of which has wave-like solutions with finite propagation speeds, and the other of which propagates information infinitely fast -- I assume you know which one is which) then I would really be concerned about a mental deficit. Fortunately, the distinctions between hyperbolic, parabolic, and elliptic PDEs is as clear to me today as it was in graduate school, or as it was pre-surgery. I guess we can conclude that the tumor was far from the PDE center in my brain.

Or another thing that would have devastating personal consequences would be if the "thermodynamics" center were affected. For example, if I agreed with any of the following erroneous statements, it would be clear and devastating evidence of a career-ending brain disorder:

  1. It is possible to fully convert heat into work.

  2. Entropy can be destroyed.

  3. Energy can be created.

  4. Global warming is not a problem, no need to change anything about our society to minimize emission of CO2.

  5. Perpetual motion machines are possible, and research into these "novel concepts" deserves DOE funding.

Fortunately, as far as I can tell, my "thermo center" is still functioning well. This means I will be able to keep working on my current research projects, including:

  1. A new collaboration with Sossina Haile in Materials Science, funded by Stanford's Global Climate and Energy Program, to develop high performance solid oxide fuel cell electrodes using recently-developed nanofabrication methods.

  2. The ONR "Research Tools" program, in which we are developing quantitative models and modeling tools for high-temperature solid-state electrochemical systems

  3. Cantera, my object-oriented C++ software package for simulations involving coupled chemistry, electrochemistry, transport processes, surface chemistry, etc.

  4. Our DARPA-funded work on plasmon-enhanced heating via nanoparticles as a tool for deposition of nanostructures, and for pumping, distilling, and concentrating liquid solutions for "lab on a chip" applications.

Also, a mental deficit in the "software center" would be devastating for me professionnally. This could be diagnosed by checking for agreement with any of the following erroneous statements:

  1. If a project presentation has colorful PowerPoint slides, the science must be good.

  2. MS-Windows is just as good an operating system as Mac OS-X.

  3. Fortran 77 is a fine programming language; I don't need to learn any C++.

As far as I can tell, my software center is still intact.

So in summary, it seems the essential parts of my brain for my life and work are still functioning as well as ever (but unfortunately no better than previously... ). So somehow this ~ 1 inch by 1.5 inch tumor was located in some part of my brain that doesn't seem to do much of anything. Perhaps it was located in the "team sports playing" center, or the "civic club joining" center, neither of which seem to work anyway.

Well, that's about all for now -- its nearly my bedtime. I suspect some of you may be thinking about now: "Don't you just hate it when someone thinks surviving brain cancer suddenly makes them qualified to be a stand-up comedian?" I suppose it is possible that I have a deficit in my "tasteful humor" center, or my "knows when to shut up" center. If so, probably years of therapy will be needed...

OK, good night all!

1 comment:

Hypatia said...

You are definitely qualified to be a blog comedian in any case... I should be working but here I am, down in Thomas 104, smiling at your jokes... glad to know you are still above the 99th percentile, Dave!