IN ONE SENSE there’s a clear boundary around the brain. Reach into a cracked-open skull, peel away some membranes, and you can wrap your hands all the way around one. And in school diagrams, it’s clear where the brain stops and the rest of the body begins. The brain is that pillowy ball of pink, sometimes with a tiny tail at the bottom, sometimes not, floating in the middle of the head. In one sense, there’s a clear boundary around the brain. That boundary is an illusion.
Tug on the brain and you will discover that it’s attached to a sturdy stem, a brain stem, which is attached to a cord, which is attached to a network of nerves extending to every organ in the body, to the tip of every finger, to the tongue, to the eyes, to the skin, to the nose. The body is suffused with nerves, and is continuous with the brain.
The brain and the body are inextricably interconnected. How could you draw a boundary between them? A human being is an air-breathing volley of life forces, chemical and electric, echoing through the brain and the body, fluids and ions filtering through its tissues, tides in a singular ocean.
Any dotted line drawn around the brain, no matter how precise, is a lie. For the boundary to be meaningful, you’d have to draw the line not only around the brain, the crown jewel of the nervous system, but also around the entire nervous system, around the whole body in fact, stretching your dotted lasso into a three-dimensional web that coats the human figure like a form-fitting glove. Even that glove would be an illusion.
A human brain
OF ALL THE ORGANS, the brain's reach is the most difficult to contain. A brain isn’t bound to the interior of the body in the same way that kidneys are. The kidneys are connected to the world outside the body only by the tubes of liquids they receive and the streams of urine they produce. The only windows kidneys have are urethras. A brain, like a kidney, is a dark organ too, of course – human bodies aren’t illuminated on the inside, after all – but a brain, unlike a kidney, has many windows.
A brain can’t see light directly, but it’s connected to nerves that exit the skull through tiny holes and hook up with eyeballs on the outer surface of the body, the surface of the body where light happens. There’s no light in a living skull, but from its bony cave, hidden from the sun, the brain participates with the phenomenon of light indirectly, via the organs of sight, and vision happens. A brain can’t see or touch or hear or smell or taste or feel the world outside the body, but it can participate with this world through its connections to the sense organs.
The brain is inseparable from the rest of the nervous system. The nervous system is inseparable from the rest of the body. And the body, via its sense organs, is inseparable from the world it inhabits. In other words, the brain transcends the boundary of the human body. This role of the brain (its boundary-crossing participation with the world) is the brain’s most characteristic feature, yet it's the hardest to depict on a diagram. Instead we draw a floating object, artificially isolated, its parts labeled with names and letters, and we end up conceiving of the brain in that way, as an object in a dark box.
THINK ABOUT IT this way. There are two levels to consider: the level of the brain and the level of the whole human being. At the level of the brain, the brain feels like tofu when you poke it. Brain is spongy and salty. You can wrap your hands around it. At the level of the whole human being, the human form is a three-dimensional sculpture, a starfish-shaped animal stretched with skin, a flexible organism that can somersault, giggle and juggle.
Imagine the outline of a human figure. Now trace a dotted line around it starting at the left hand. Trace your finger around the fingers of the left hand, up the left arm, around the head, down the right side of the arm, around the fingers of the right hand, down the right side of the body, around the toes of the right foot, the left foot, up the left side of the body, then back to the left hand where you started. At the level of the whole human being, the brain is out of view.
A human being
AS A BRAIN INJURY doctor, it's helpful to consider both levels when directing a course of treatment.
If I’m treating a person with a memory impairment, I can work at the level of the brain by prescribing medications to influence the brain’s chemistry in an effort to enhance memory function. I can also un-prescribe medications that may be exacerbating memory impairment. Working at this level, at the level of the brain, it’s important to understand the chemical context of the brain, how drugs interact, what side effects they produce, how they do or don’t cross the blood-brain barrier, neurotransmitters, etc.
And working at the level of the brain – when designing prosthetic brain parts, for example – it’s important to understand the physical properties of the brain. In his bio-electronics textbook, Toward Replacement Parts for the Brain, Dr. Theodore Berger devotes three chapters to a discussion of the challenges presented by neuron-silicon interfaces, that space where two surfaces normally alien to one another – tofu and electronics – meet and co-exist.
MEMORY ISN'T something that happens only at the level of the brain. Memory isn’t a cartridge that can be snapped in and snapped out. How do you remember what day it is without looking at a calendar? How do you know where you are without seeing what’s around you? How do you learn to juggle without ever juggling balls? Memory is all around us. Memory doesn't inhabit our brains. We inhabit memory. So the rehabilitation of a memory impairment should focus there as well.
Traditional formal therapies (physical therapy, speech therapy, occupational therapy) operate at the level of the whole human being. They achieve recovery of function by engaging a person in repetitive exercises or guided movements. Cognitive rehabilitation therapy is based on similar principles. The idea is that specific cognitive skills, memory skills for example, can be rehabilitated through repetition of exercises in the same way that specific physical skills can be rehabilitated through repetition of physical exercises.
Although it’s the brain that’s been injured, the brain isn’t only the level where treatment should take place.
Cognitive rehabilitation therapy, like physical therapy, takes place at the level of the whole human being, where the rubber of the body, so to speak, hits the road. The brain is re-shaped in this process, yes, so healing is also happening at the level of the brain, but only indirectly by engaging a person at a more global level, in the same way that the injured brain of a person with a paralyzed arm is re-shaped through active use of the arm, or in the same way that the musculature of the heart is re-modeled and re-conditioned by running on a treadmill. Working at the level of the whole human being, practicing memory exercises over and over and over, brings about a change within. It’s an outside-in approach.
IT'S POSSIBLE to treat memory function at the level of the whole human being by providing external memory supports, in other words, prosthetic memory.
Say a pink balloon pops in front of your face – pop – and you write SEPTEMBER 15, A PINK BALLOON POPPED in chalk on a piece of slate. The next day, another balloon, a yellow one, pops in front of your face – pop – and you write SEPTEMBER 16, A YELLOW BALLOON POPPED on a second piece of slate. You put the two pieces of slate in a safe.
Fifty years later, a stranger asks you which of the two colored balloons popped first, the pink one or the yellow one, and you honestly can’t recall which one it was. Then you retrieve the two pieces of slate from the safe. You read the chalk writing and say, “It was the pink one.”
The chalk writing records a momentary experience – a balloon popping – and preserves the brief occurrence as a lasting memory which can be retrieved at a later point in time. Chalk and slate work, not at the level of the brain by replacing a human brain part, but at the level of the whole human being by replacing a human function. Chalk and slate do what the hippocampus does, even outlasting or outperforming the native memory organ. It depends on the clarity of the writing and the persistence of the chalk. Think of what longevity more durable materials have achieved: clay tablets have been preserving human memories for over four thousand years old, much longer than the life span of any human brain.
WE ASCRIBE MANY functions to the brain, memory included, which are properly ascribed to human beings at a more global level. People confuse the two levels all the time. On the radio last week I heard a scientist say, “This is what the brain looks like when it’s asleep,” as though brains and not people were the things actually sleeping.
A neurosurgeon, Henry Marsh, wrote in a blog post recently, “I look down the operating microscope, feeling my way through the soft white substance of the brain, trying to find the tumour. The idea that I am cutting and pushing through thought itself, that memories, dreams and reflections should have the consistency of soft white jelly, is simply too strange to understand and all I can see in front of me is matter. (1)” The reason it seems strange to him is because it isn’t true. He’s zoomed in too close. Memory doesn’t live only in the brain. Memory is all around us. The brain and the body participate with the body’s environment, and that’s how memory happens.
Because the brain is inside the head, and because we falsely believe that things like thoughts and memories may be found inside a brain, we falsely believe that thoughts dance around inside our heads when we think them. But thoughts don't live in brains. Brains don't think. Human beings think. Brains are quite stupid on their own, as anyone who has seen a brain floating in a vat of formaldehyde could tell you.
IT'S AN OBVIOUS statement, but one that bears mention: Brains aren't people. They're two different things entirely. Brains don’t sleep. People sleep. Brains don’t see. People see. Brains aren’t happy or sad. People are happy or sad. Brains don’t pay attention. People pay attention. Brains don’t fall in love. People fall in love. Brains don’t swallow apricots. People swallow apricots. Brains don’t remember. People remember. Brains don't think. People think. People use their brains to remember, of course, but they also use more than their brains to remember. They use their bodies. They use their environments.
A brain is an essential ingredient of memory, to be sure, and when a brain is injured, the capacity for thought in all of its manifestations suffers. But to say that memory inhabits the brain, or that memory lives in the brain, that the brain contains memory, is to confuse the level of the brain with the level of the human being.
No matter how deeply we peer inside the brain, we will never be able to locate memory fully inside it. Memory is a phenomenon in which the brain participates, but it’s also a phenomenon in which the body participates. The brain isn’t a container for memory. Memory operates on a more global level, involving not only the brain, but also the whole skeleton-and-flesh framework of the human form and its exquisite interactions with the world surrounding it.
The same can be said of emotion. No matter how deeply we peer inside the brain, we’ll never be able to locate emotion fully inside it. Emotion is a phenomenon in which the brain participates, but it’s also a phenomenon in which the body participates. Emotion, like memory, operates on a more global level, involving not only the brain, but also the whole skeleton-and-flesh framework of the human form and its exquisite interactions with the world surrounding it.
I can zoom in and direct treatment for emotional impairments at the level of the brain, working from the inside out by prescribing medications. But I can also zoom out and direct treatment at the level of the whole human being, working from the outside in by prescribing repetitive exercises or emotional supports. Without a clear understanding of the distinction between the two levels, without a two-pronged approach, treatment won’t be as comprehensive as it could be.
REFERENCES
1. New Voice: Henry Marsh. Granta 120, Spring 2012.
http://www.granta.com/New-Writing/Henry-Marsh