The Ghost in My Brain (22 page)

In particular, my ability to
think
was gradually expanding, and I could do so with less fatigue.

Zelinsky's glasses had given me access to new paths in my brain, and the work with Donalee was pushing my brain to grow and develop along those new channels. The plan made sense. The work made sense. The results were coming.

Thank you, Donalee—you called me back!

Before we return to Zelinsky's lab to delve into the fascinating world of an optometrist whose work is based on neurodevelopmental research, it's important to first learn something about how the human visual system works. Then we'll walk step-by-step through my recovery using what we have learned to explain the details of
why
treating my brain's visual system was so crucial to my recovery.

A QUICK TOUR THROUGH THE VISUAL SYSTEM.
There are three retinal processing pathways through the brain. Two of these, for
central vision
and
peripheral vision,
are for eyesight and are processed in the brain's visual cortex. The third is for
non-image-forming retinal signals
(also primarily from the peripheral part of the retina) that branch off and are processed
by other body systems such as for posture control, for sleep rhythms, for the production of melatonin, etc. Each of these is crucial to our well-being, as is the coordination among them.

There are roughly 100 million receptors in the retina of each eye, which respond to light, but there are only a million
axons
leaving the retina, so the many layers of the retina together act as a very sophisticated sensory filter. Additionally, the retina acts as a
transducer
that converts light into neural signals: input
photons of light
enter through the lens, pass through a
chemical stage
in the early retinal layers, and then move on to a later
electrical stage
comprising the neural signals sent out along the axons. Axons are bundled together, depending on which area of the retina they come from, and this also determines the route they will be taking through the brain. The collected bundles of the one million axon output fibers form the
optic nerve
for each eye.

Vision signals spread out and are routed along many different paths known as
optic radiations
to the back of the brain where the visual cortex resides. Different parts of the visual cortex process, first,
movement, location, size, and shape
from the peripheral vision, and, second, lagging just slightly behind,
colors and details
from the center vision (though see the footnote
here
). This is what is classically thought of as the “visual system.”

Thus we have a chain of crucial steps in translating light into meaning: how light is transmitted through the clear cornea and lens of the eye, how the various sections of the retina are activated, how the photoreceptor signals are reduced to the axon output, how activation is dispersed among the various axon bundles in the optic nerve,
how the signal is routed to the visual cortex,
and how the signal is passed on by the visual cortex to the rest of the brain, which gives it meaning.

But we are not done. In the past ten years, retinal research has shown that there are many other
non-image-forming pathways
from the retina to various body systems. These channels affect the “homeodynamics” (dynamic self-organization) of the body—through hormones, enzymes, and other mechanisms. For example, there are receptors linked with thyroid function, pupil dilation and constriction, dopamine production, and adrenaline production. Consider that when light cycles change we can experience jet lag, or seasonal affective disorder, and those who are completely blind may have to deal with circadian rhythm challenges because of
non-24-hour sleep-wake disorder
. One can easily understand the powerful effects of this non-image-forming retinal input as follows: imagine that a gigantic spider suddenly crosses into your peripheral field of vision. A jolt of adrenaline will begin flooding your body well before your conscious mind interprets the threat. In fact these non-image-forming retinal signals are always given precedence: the signals travel faster and are processed first; when our bodies are under high stress we often cannot pay attention to what we are seeing with our central-image visual processing.

And for each of these paths, a complex network of feedback signals continually biases the whole system—altering the information that is passed on to the brain.

Ultimately, almost every part of the brain gets involved, because the processing of visual/spatial information is linked to symbolic thought, body sense, motor coordination, memory, balance, hearing, and so on. Along the way to the visual cortex, signals from other sensory systems are integrated, such as those for hearing and proprioception.

Nor can the retinas be considered as simply input devices, because signals also return to the eye in response to cognition
and body states (such as emotions), to make significant chemical and electrical changes in the retina, and to control both eye movement and filtering in the retina. For example, a depressed person may have signals returning to the eye shutting down peripheral awareness (shutting out the world), whereas a person with ADD might have signals
emphasizing
peripheral awareness (distracted by everything). In this way, vision is a complex process, closely integrated with the inner workings of the brain. Note that when we are not looking at anything at all, but simply thinking, our eyes will move in very specific ways according to our thoughts. From a scientific standpoint, our eyes really are windows into our souls.

In her practice, Zelinsky alters the input into each of the two eyesight systems, as well as into the non-image-forming retinal systems, makes very sophisticated measurements and observations of the resulting output, and then uses this information to make deductions about the likely nature of the brain processes leading from the former to the latter.

Critical to Zelinsky's work—as we will see shortly—is the idea that by activating different parts of the retina, she can
alter the paths through the optic radiations
that the retina's eyesight signals will take on their way to the visual cortex, and also
the paths of the non-image retinal signals
that branch off from the optic nerve before they get to the optic radiations.

There are three ways that Zelinsky uses light to alter the way the brain operates. First, she can bend the light to
different parts of the retina
, which, ultimately, activates bundles of axons differently. In other words, the same visual/spatial signals are being sent, but they are being filtered differently (in the reduction from 100 million to 1 million in the retinal layers), and are being routed differently (through different bundles of
axons). When we consider that 100 million receptors are packed into about a square inch of the retina's surface area, it is obvious that even very small changes in the optics can make a huge difference in which receptors are being activated.

Second, Zelinsky can change the
frequency of the light
by allowing different colors through to the retina. Roughly speaking, when the frequency of the light changes, different frequency-sensitive photopigment chemicals, such as melanopsin (~480 nanometer wavelength sensitivity) and rhodopsin (~500 nanometer sensitivity), cause different photosensitive receptors in the same area of the retina to become activated. Thus, while the light may still be hitting the same part of the retina, different cells become activated, ultimately changing the output signals in the optic nerve.
*
The science of this process of frequency filtering gives new meaning to the phrase “seeing the world through rose-colored glasses.”

Third, Zelinsky can selectively
block signals from reaching the retina
at all through using occlusion filters that simply reduce, or block out, the light to certain parts of the eye.

With change either to the location of where the light strikes the retina, to the frequency of the light striking it, or to the amount of the light striking it, the result is that the signal load is dispersed differently through the pathways in the brain.

This is where the principles of
brain plasticity
—one foundation of modern brain science—come into play. When the brain is damaged, such as from TBI, it is possible that the retinal output signals might be fine, and the visual cortex might even be in
good shape, but the pathways between the two, or the areas around the pathways with which the axons interact, are damaged. Signals along the old paths are degraded (think of “picking up static”) because of the permanently damaged tissue. By bending the light in the eyes, selectively occluding it, and changing the frequency of the light, Zelinsky is able to avoid the damaged routes along which the visual/spatial signal travels.

To greatly simplify this staggeringly complex system, considering eyesight only, let's imagine that there are only one hundred different paths along which signals travel from the retina to the visual cortex. Now let's imagine a patient with brain damage from TBI for whom twenty of these paths have become permanently damaged. On suspecting this, Zelinsky would try to change the input to the eye so that the eighty remaining paths were emphasized and used more heavily, and the twenty defective paths were avoided, in carrying the same signal to the visual cortex. Think of rerouting traffic from a highway, U.S. 25—which has been damaged—to highways U.S. 40, U.S. 50, and U.S. 60—which are still in good shape. The same traffic is getting through, but it is taking a different route.

Through habituation, when the new pathways through the brain are established, the healthy tissue adapts, and the magic of the brain's plastic nature takes over. Within a very short time the new brain tissue learns its new tasks in conveying the visual/spatial signals to the visual cortex. Because it is healthy, the signal path is once more restored to its full capacity without distortion. And, once the brain learns to process the signals along the new paths, the need for the remedial help in “jump-starting” the new paths may become unnecessary.

This explains why I tried many kinds of brain exercise over the course of eight years, but only experienced distress, and pain,
with even the simplest sorts of intellectual tasks: I was simply repeatedly sending signals along the old, well-worn, but now damaged, paths.
*
And this is why the standard medical response for brain damage is “learn to live with it, because you'll never get better—no one ever does.” And yet, within two weeks of getting my first pair of brain glasses, my plastic brain had reconfigured itself, learning to follow healthy pathways through to the visual cortex—and I was vastly, hugely improved. Additionally, although I can't claim it as part of the science, it is my strong intuition that the constant onslaught from bad visual/spatial signals required parts of my brain to simply shut down because the input was too exhausting to process. Once the signals were sorted out, those parts of my brain—used in complex spatial cognition and symbol manipulation—could come out of hibernation.

WORKING WITH AN OPTOMETRIST EMPHASIZING NEURODEVELOPMENTAL REHABILITATION.
Having laid the foundation, we can now walk through the processes that Zelinsky uses to translate her knowledge of the image-forming and non-image-forming retinal systems into the practical matter of making people's brains function the way they were intended. The first step is determining the current state of a patient's brain, and for this Zelinsky uses an extensive battery of tests, along with intuition based on her years of clinical experience.

In that first trip I took to Zelinsky's office, I went through more than fifteen different visual/neurological testing procedures, some of them formal, and some of them less so—but
still important information for Zelinsky, who was looking for subtle clues to my brain's organization. Many of the tests were repeated in subsequent visits, with Zelinsky looking for checkpoints as she pushed my brain processing in a very specific direction.

After my brief introduction to Zelinsky, I filled out a long set of questionnaires, and also wrote essay responses about my habits and my specific complaints.
*
Based on my responses, Martha asked me a series of further questions that helped to diagnose my lifestyle, which in turn gave clues about the organization of my brain. I also brought along several pages of notes on my TBI symptoms that Martha read, summarized in my chart, and then passed on to Zelinsky. I later discovered that Zelinsky
always
read everything I brought her.

The first test Martha gave me was called the
Padula Visual Midline Shift
test. I was told to look straight ahead. Then Martha brought a horizontally held chromium steel shaft, like a skewer for a barbecue, from above down toward the ground so that it gradually entered the middle of my visual field.

She said, “Tell me when the shaft is directly in front of your eyes.”

She then repeated the movement, but this time from the ground upward. In this way my top-to-bottom
midline
was determined. The exercise was then repeated from left to right, and right to left.

In normals, these stopping positions will be about the same, and the midlines—horizontal and vertical—will intersect at a
crossing point directly in front of a person's eyes. For those of us with TBI or other brain oddities, the midline may be shifted higher or lower than normal, to one side or the other, or both. In other words, the internal 3D spatial world is no longer lined up with the world coming in through the senses.

According to William V. Padula, the designer of the testing mechanism, when a person has a midline shift—associated with the
ambient visual process
*
—she may have balance and coordination problems, and have trouble making out the details in a visual scene.
*
Without grounding in this non-image-forming and peripheral retinal processing, the world may become broken into isolated parts, such as what happened to me whenever I went shopping: all the items on the shelves are suddenly experienced as a kaleidoscopic nightmare of overwhelming detail without any context in which to sort them out. The central eyesight processes then have to take over, trying to make gestalt sense of the scene—performing tasks for which they were not designed, causing motor responses to become slower and slower. Cognitive confusion and distress can also result.