The Ghost in My Brain (17 page)

SENSORY FILTERS.
All input and output from our brains takes place through the medium of our bodies, and thus the two are highly integrated. In some views they are inseparable. But with concussion the relationship between the brain and the body can change, and for the concussive there may be many unusual and disconcerting experiences as a result.

One common experience I had was that under cognitive stress my
sensory filters
would change. These filters have two main jobs. First, they operate to exclude most of the potential input because it is not of interest to us. Second, they chunk together pieces of the remaining input into
meaning.
Additionally, these two processes work together: In a greatly simplified version we might imagine there are twenty layers of such filters. At each level the filtered and concentrated input signal is passed upward toward the rest of the brain—gathering meaning along the way. But at the same time signals are also sent back downward (toward the original body sensors) to further bias the way the previous layer applies its filtering. In this way we get raw input from the bottom up, but also, at the same time, a continuous stream of biasing information helping us to “know what to look for or listen to” that is passed back from the top down. In this way we eliminate increasing portions of the incoming signal as irrelevant to the context and meaning we have now partially determined.
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The brain also works with the extended body to control the process of gathering input information by changing our posture orientation, by changing the properties of our eyes (including, e.g., the balance between the different retinal systems), by affecting the level of our physical arousal, of our hormone balance, and so on, each of which affects how we appraise the world.

Consider, for example, the following “London in the rain” exercise. I wrote it on the whiteboard in one of my undergraduate AI classrooms before the students arrived, then asked them during the lecture what it said:

Figure 1:
London in the rain!

Naturally they told me that it said “London in the rain.” When I asked them again to tell me what it
really
said, they replied, “London in the rain.” At the end of fifteen minutes of this, my forty students were ready to lynch me, and to avoid a mutiny I had to manually explain their mistake. (Carefully count the words in the illustration, pointing to them with your finger.) They literally
couldn't see
the words in front of them.

In this case, subliminal error correction in the students' brains altered their perception, and probably yours as well—a sensory filter. This is an example of our brains chunking together small bits of information to form
meaning
under control of what our brains are expecting to see.

After suffering the concussion, at times of brain fatigue, I often lost efficacy in my sensory filters. As we have seen, I would, instead, get a flood of sensory information—bits and pieces of the world—with no gestalt meaning attached. I had to construct meaning manually, putting together raw pieces of information, such as shapes and colors and the sounds that came with them, to make sense of the world around me.

BODY-SENSE COGNITION AND BRAIN FLU.
At other times, because of impoverished visual and balance systems, I would need to rely on my
body
feelings
partly as a way of constructing the internal symbols of thought. When I couldn't
see
meaning in the input, I would
feel
it instead. This is difficult to describe, because it is not normally something we think about, and understanding it is also not intuitive. Yet it was an important mechanism that helped me reason about the world, and a capability that we all probably use to a lesser degree without realizing it.

Let's imagine that I ordinarily have a visual/geometric representation of the concept
conflict:
say (for simplicity's sake)
The
Blue Team
on the left, pushing and tugging against
The Red Team
on the right, one side against the other. But on this day, because of visual system fatigue I've lost the ability to
see
this concept. But my body and emotion system are functioning as normal. Now, to make up for my internal visual deficits I substitute the much more abstract emotion concepts of
pathos, desire, feeling of accomplishment,
and so on, which I can still clearly experience as felt emotions in my body. These can be combined in various ways to represent conflict: if
Blue
and
Red
both
desire
the goal
G
, and Blue
feels pathos
when Red
gets (accomplishes) the goal
G
 . . . then they are in
conflict.
In this way I could use body representations to manipulate the logic relative to
conflict
in place of the internal visual symbols that had deserted me. In the general case,
I could use body information to reason about the world.

As a concussive, I used this sense of my body all day long—to check my surroundings, to arrange for remedial help with balance, to substitute for other kinds of symbolic representations that I could no longer map to problems in the real world, and so on. But when I got a cold, or was fatigued and sore from a hard run, my body sense changed, and this presented cognitive difficulties.

To illustrate, let's further imagine that I am grading papers for class, but on this day I have a cold. After finishing a few papers, I am losing the ability to visualize internal concepts, including
conflict.
But now, because of the cold, my body already feels feverish, which is similar to the feeling for
pathos,
and I am no longer able to feel the emotion in the usual way. But having lost pathos, I have also lost
conflict
, and without conflict I can't understand the phrase “. . . the conflict between using
the most efficient algorithm, and the one that is least susceptible to failure” in some graduate student's homework.

Getting a cold or the flu thus not only was a physical problem, as it would be for normals, but also was attendant with the much more taxing cognitive difficulties engendered by losing many backup mechanisms for forming the symbols of thought that would get me through the day.

Perhaps it helps to think of it this way: my cognitive/sensory landscape was often a changing and unfamiliar environment, without inherent symbolic
meaning
, and requiring much thought to figure out. By contrast, my body state was relatively constant, and I was thus generally able to use this grounded proprioceptive sense, and other body feelings, to form nonvisual symbols that still allowed reasoning and problem solving to take place. But when I lost the grounding of my body sense because of illness or physical fatigue, I could no longer form these nonvisual symbols in the usual way. My internal landscape became just as unfamiliar as the unfiltered external sensory stream was.

This can be a perplexing weakness. It often left me asking myself, “What is
wrong
with me? Why am I so incapacitated by a simple cold?”

SEIZURES AND OTHER STRANGE PHENOMENA.
When someone gets a concussion there may be odd physical failures that can occur in addition to the cognitive changes, and I experienced a few of them myself.

Under certain kinds of cognitive loads that involved my making sense of
lines
—especially parallel or concentric lines, and also in some cases geometric rotations of shapes that had well-defined edges that could be perceived as lines—I would
start having mild brain seizures that caused my whole body to shake from side to side. Here is an episode from my notes that illustrates how this would happen:

September 2004:
Several days ago I had a large photocopying job that I had to complete before the day was out. I was at the UPS store doing my best to keep the various piles of originals from getting mixed up. It was a complex job, entailing sorting and copying collections of documents, translating two-sided originals into one-sided copies, and so on. The intense visual appraisals required for the mental rotations—top-to-bottom, front-to-back—soon left me disoriented. Because I had a hard deadline, I had to draw extensively on my deep cognitive batteries and keep going—no matter how I felt. There were other customers waiting behind me, adding social pressure.

Because of the
geometric
visual demands, I started to experience tremors that caused my whole upper body to shake back and forth. It was embarrassing to hear the “flap! flap! flap!” of the papers waving around as I worked. I kept going, and finished the job because I had to, but it was startling for others in the copy shop to watch—the shop owner offered to call an ambulance for me—and it was a real struggle for me to get home afterward. The seizure movements tapered off and finally stopped after three days.

I experienced these seizures to one degree or another about thirty times, and always with visual triggers—although it was some time before I made this connection. They lasted from a few hours to a few days. I was often afraid that these were precursors of an impending neurological collapse, but in the end, with rest, they always went away. I didn't want to take any chances with them, and when I began experiencing seizures I took this as a sign that I had to let virtually everything else go.

In March 2008, at which point I was well into my recovery, I was more confident, and my scientific curiosity took over. I found that if I tried to mimic the seizure movement manually, I could only approximate it, and I would get tired in only a minute or two. By contrast when the seizures came over me from geometric triggers, they might last for days and I wouldn't feel any muscle fatigue at all. With experimentation—at times of relatively low stress—I found that just by drawing concentric circles on a sheet of paper I could trigger an episode in as little as four minutes. I would draw a small circle, then another around it, and another around that one, up to five or six concentric circles. Then I'd start another design next to it. For variation I might mix in concentric squares.

After two horizontal rows of designs (ninety seconds) I started to feel the effects, and also as though I were “falling into” the shapes when I looked at them. After half a page of designs, if I stood up, and relaxed, I would have the seizures, and they would last for about twenty minutes.

I was able to function well—talk, grasp things, etc.—but I had to be careful not to drop items or knock them off counters or a table top when I was picking them up. My walk was affected: I sort of stumped along, straightening my knees more than usual at the extension point, flinging my feet forward, instead of stepping.

My intuition is that if I pushed myself, say by drawing five or six pages of concentric designs, the tremors would last for several days.

 • • • 

Another brain-wiring problem—and the scariest one—came from a surprising source: itching.

Sometime after the car crash I realized that I could no longer effectively locate where certain kinds of back itches were, and without my being able to scratch them, they would not go away. I could feel where the itch was
supposed
to be on my back, but scratching there didn't relieve the itch. Instead I had to generally scratch all over my back, my shoulders, and my upper arms, and sooner or later the itch would gradually recede. But for this kind of itch there was never a sense of finding “the” spot. I never actually relieved the itch directly, by scratching, which is, in itself, unpleasant. (Think of a sneeze that just fades away.)

This may seem like a small problem, but I have many times thanked my lucky stars that I have at least been able to get the itch to slowly go away by scratching everywhere. What a maddening—and even potentially catastrophic—thing it would be if my random scratching were not able to get this phantom back itch to stop! To give some context about how serious this can be, consider the case in which another sufferer of a phantom itch went almost mad, and indeed ultimately scratched through not only her scalp but also her skull bone and into her
brain trying to get relief from an incessant itch that she could not control.
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