BOOST YOUR BRAIN by Majid Fotuhi, M.D., Ph.D. (ZT)
I had started medical school with a deeper well of medical knowledge
than the average student--at least when it came to brain-related
matters--having taken the unusual route of completing my Ph.D. in
neuroscience at Johns Hopkins University before I started medical
school. I was actually in the M.D. program at Harvard by way of a
teaching scholarship offered through Harvard-MIT Division of Health
Sciences and Technology, which put me in the unlikely position of
teaching neuroanatomy to my medical school classmates while I was a
student myself. I knew neuroscience. But for medical conditions
below the neck, I was in much the same position as my classmates:
nervous, but also eager to learn everything I could about the human
body.
So, it was with equal parts uncertainty and excitement that I
greeted my obstetrics professor as she sauntered over to me in the
delivery room that day. Motioning to a nineteen-year-old woman who
was nearing the final stages of labor, she said, "You'll deliver
this one," turning an ordinary day into one I will never forget.
In the delivery room, I was gowned and gloved and, I'll admit,
sweating profusely as the baby began her trip down the birth canal.
A new life was entering the world and I didn't want to mess it up.
Thankfully, everything went according to plan, and after the
mother-to-be gave a few final pushes, I eased the baby into my
hands. Now, this is an incredible moment even after you've
experienced it a few times, but I'll never forget the feeling I had
sitting there, amid the happy tears of the new mom and her family
(and even a few of my own), holding that baby girl, who would soon
be named Sara.
Nine months ago she was a microscopic bundle of rapidly dividing
cells--first two, then four, then eight, sixteen, and on (into the
trillions!). How could she have grown into this bawling, squirming,
perfectly formed human? Along the way, a million things could have
gone wrong. And yet, here she was. With eyes that one day would be
able to distinguish several thousand shades of color, a complex
auditory system capable of transforming vibration in the air into
sound (and turning those sounds into intelligible thoughts and
concepts), and a heart that would beat some hundred thousand times a
day, every day.
One year later, having spent time training in the pediatrics,
psychiatry, cardiology, and medicine wards, I was doing another
rotation in my life as a medical student, this time in
neuropathology, an elective whose choice reflected my fascination
with the human brain. Neuropathology, the study of diseases of the
central nervous system, involves performing autopsies to detect
disease in the brain (both by examining it first with the naked eye
and later under the microscope), and I was as eager to jump in as I
had been on my obstetrics rotation. I was grateful, too, to finally
spend weeks focused on exploring the brains of patients who had
Parkinson's disease, multiple sclerosis, head trauma, and
Alzheimer's disease. By comparing their brains to those of otherwise
healthy elderly people who had died of natural causes, I knew I
would gain a new understanding of the workings of the brain and how
it changes with aging and disease.
Just as I had for the OB rotation, I progressed in steps, first
watching someone else perform a brain autopsy, then inspecting an
already-prepared brain, and finally, handling the delicate procedure
of removing the brain from the skull. But unlike in obstetrics,
neuropathology takes place in a morgue, a cold, sterile room--think
bare walls, metal tables, and concrete floors--inevitably tucked
away in the bowels of the hospital building. There's another big
difference: in neuropathology, patients don't cry or squirm or come
to harm if you make a wrong move.
Still, the brain can't be properly studied if it's handled roughly
or, God forbid, dropped. And you only get one shot at successfully
removing it from the skull.
My moment to perform a brain autopsy finally came one weekend
morning with a call from the morgue. "If you want to do this one,
come on in now," the professor I was working with said. I hopped on
my bicycle, pedaled to another Harvard teaching hospital,
Massachusetts General Hospital, and quickly changed into hospital
scrubs. Awaiting me in the basement morgue was the body of an
eighty-five-year-old woman who had died of aspiration pneumonia and
had suffered from dementia. Her name was Mrs. Grey.
By this point, I had seen enough cadavers and exposed brains that I
was quite comfortable entering the morgue and preparing for the
autopsy. Still, as I donned my protective gown, face mask, and hood,
I felt a nervous anticipation that wasn't too unlike those days in
the delivery room.
To remove the brain from the skull, the coroner and I first had to
cut away the top of the skull, just above the eyebrow, with the help
of an electric saw. There is some delicacy needed: slice too deeply
and I'd destroy the delicate grey matter within. Once the skull was
cut, I set the bowl-like top piece aside and gently pulled the brain
outward, making space to slice away its attachment to the spinal
cord. I then eased Mrs. Grey's brain out and let it fall gently into
my cupped hands.
A brain has the consistency of Jell-O and, like a baby, it is
fragile--and a little slippery. In a moment, I would weigh it,
examine it visually, and then place it in a formalin-filled bucket
to preserve and harden it so that it could be dissected and observed
under a microscope. Even without a microscope, though, I could see
the ravages of time--instead of the plump peaks and minimal valleys
of a young, lush brain, Mrs. Grey's had deep ridges separated by
wide spaces.
As I cradled Mrs. Grey's brain in my hands, I remember marveling in
much the same way I had on the day Sara was born. In my hands were
three pounds of cells that had powered an entire life. It was the
very essence of that life: the neurons and connections that spurred
Mrs. Grey to volunteer at the library on weekends, smile when she
saw her grandson's face, or get grumpy when she was stuck in
traffic.
In between the moment she'd first seen those bright delivery-room
lights and the moment her last neuron had fired, every experience
her brain had encountered shaped the person she became. And yet, no
one at the time would have suggested that how she lived her life as
an adult had substantially altered the size and structure of her
brain. At the time, in the mid-1990s, the human brain was widely
believed to finish its development and become fixed in structure by
childhood. After that, there would be only one inevitable
possibility for structural change: the brain would shrink with age.
That's what everyone thought. But, as you'll soon learn, "everyone"
was undeniably wrong.
Your Brain, Baby
What happened to Mrs. Grey's brain in those eighty-five years
between birth and death? And how did changes inside her brain affect
her cognitive abilities throughout life? How might she have steered
those changes in one direction or another--and to what end?
Mrs. Grey's story started the same way that Sara's had: with a tiny
clump of cells. I'll stick with the simple version of brain
development and aging, but even simplified it's an incredible tale.
Human life, after all, begins as one cell and ends with some hundred
billion in the brain alone.
We can start the story of Sara's brain by taking a peek inside her
mom's uterus at about the third week of gestation. Remember those
dividing cells? At about this time, some will form a column of cells
the shape of a tiny tube. At one end of the tube, cells will develop
into the spinal cord, while at the other end cells will develop to
form the brain's two hemispheres. Most of these cells become neurons
and at one end will have extensive branches--tens of thousands of
them--called dendrites, which will act as antennae to receive input
from other neurons. At its other end, each neuron will sprout a
single long extension called an axon, which in turn will sprout at
its tips tens of thousands of swellings called axon terminals.'
Within Sara's brain, these neurons will begin to send messages to
each other via electrical signals that "leap" from the axon terminal
of one neuron to a special docking site on the dendrite of another
neuron, crossing a gap called a synaptic cleft. Eventually the brain
will contain more than one hundred trillion such synaptic
connections.
I had started medical school with a deeper well of medical knowledge
than the average student--at least when it came to brain-related
matters--having taken the unusual route of completing my Ph.D. in
neuroscience at Johns Hopkins University before I started medical
school. I was actually in the M.D. program at Harvard by way of a
teaching scholarship offered through Harvard-MIT Division of Health
Sciences and Technology, which put me in the unlikely position of
teaching neuroanatomy to my medical school classmates while I was a
student myself. I knew neuroscience. But for medical conditions
below the neck, I was in much the same position as my classmates:
nervous, but also eager to learn everything I could about the human
body.
So, it was with equal parts uncertainty and excitement that I
greeted my obstetrics professor as she sauntered over to me in the
delivery room that day. Motioning to a nineteen-year-old woman who
was nearing the final stages of labor, she said, "You'll deliver
this one," turning an ordinary day into one I will never forget.
In the delivery room, I was gowned and gloved and, I'll admit,
sweating profusely as the baby began her trip down the birth canal.
A new life was entering the world and I didn't want to mess it up.
Thankfully, everything went according to plan, and after the
mother-to-be gave a few final pushes, I eased the baby into my
hands. Now, this is an incredible moment even after you've
experienced it a few times, but I'll never forget the feeling I had
sitting there, amid the happy tears of the new mom and her family
(and even a few of my own), holding that baby girl, who would soon
be named Sara.
Nine months ago she was a microscopic bundle of rapidly dividing
cells--first two, then four, then eight, sixteen, and on (into the
trillions!). How could she have grown into this bawling, squirming,
perfectly formed human? Along the way, a million things could have
gone wrong. And yet, here she was. With eyes that one day would be
able to distinguish several thousand shades of color, a complex
auditory system capable of transforming vibration in the air into
sound (and turning those sounds into intelligible thoughts and
concepts), and a heart that would beat some hundred thousand times a
day, every day.
One year later, having spent time training in the pediatrics,
psychiatry, cardiology, and medicine wards, I was doing another
rotation in my life as a medical student, this time in
neuropathology, an elective whose choice reflected my fascination
with the human brain. Neuropathology, the study of diseases of the
central nervous system, involves performing autopsies to detect
disease in the brain (both by examining it first with the naked eye
and later under the microscope), and I was as eager to jump in as I
had been on my obstetrics rotation. I was grateful, too, to finally
spend weeks focused on exploring the brains of patients who had
Parkinson's disease, multiple sclerosis, head trauma, and
Alzheimer's disease. By comparing their brains to those of otherwise
healthy elderly people who had died of natural causes, I knew I
would gain a new understanding of the workings of the brain and how
it changes with aging and disease.
Just as I had for the OB rotation, I progressed in steps, first
watching someone else perform a brain autopsy, then inspecting an
already-prepared brain, and finally, handling the delicate procedure
of removing the brain from the skull. But unlike in obstetrics,
neuropathology takes place in a morgue, a cold, sterile room--think
bare walls, metal tables, and concrete floors--inevitably tucked
away in the bowels of the hospital building. There's another big
difference: in neuropathology, patients don't cry or squirm or come
to harm if you make a wrong move.
Still, the brain can't be properly studied if it's handled roughly
or, God forbid, dropped. And you only get one shot at successfully
removing it from the skull.
My moment to perform a brain autopsy finally came one weekend
morning with a call from the morgue. "If you want to do this one,
come on in now," the professor I was working with said. I hopped on
my bicycle, pedaled to another Harvard teaching hospital,
Massachusetts General Hospital, and quickly changed into hospital
scrubs. Awaiting me in the basement morgue was the body of an
eighty-five-year-old woman who had died of aspiration pneumonia and
had suffered from dementia. Her name was Mrs. Grey.
By this point, I had seen enough cadavers and exposed brains that I
was quite comfortable entering the morgue and preparing for the
autopsy. Still, as I donned my protective gown, face mask, and hood,
I felt a nervous anticipation that wasn't too unlike those days in
the delivery room.
To remove the brain from the skull, the coroner and I first had to
cut away the top of the skull, just above the eyebrow, with the help
of an electric saw. There is some delicacy needed: slice too deeply
and I'd destroy the delicate grey matter within. Once the skull was
cut, I set the bowl-like top piece aside and gently pulled the brain
outward, making space to slice away its attachment to the spinal
cord. I then eased Mrs. Grey's brain out and let it fall gently into
my cupped hands.
A brain has the consistency of Jell-O and, like a baby, it is
fragile--and a little slippery. In a moment, I would weigh it,
examine it visually, and then place it in a formalin-filled bucket
to preserve and harden it so that it could be dissected and observed
under a microscope. Even without a microscope, though, I could see
the ravages of time--instead of the plump peaks and minimal valleys
of a young, lush brain, Mrs. Grey's had deep ridges separated by
wide spaces.
As I cradled Mrs. Grey's brain in my hands, I remember marveling in
much the same way I had on the day Sara was born. In my hands were
three pounds of cells that had powered an entire life. It was the
very essence of that life: the neurons and connections that spurred
Mrs. Grey to volunteer at the library on weekends, smile when she
saw her grandson's face, or get grumpy when she was stuck in
traffic.
In between the moment she'd first seen those bright delivery-room
lights and the moment her last neuron had fired, every experience
her brain had encountered shaped the person she became. And yet, no
one at the time would have suggested that how she lived her life as
an adult had substantially altered the size and structure of her
brain. At the time, in the mid-1990s, the human brain was widely
believed to finish its development and become fixed in structure by
childhood. After that, there would be only one inevitable
possibility for structural change: the brain would shrink with age.
That's what everyone thought. But, as you'll soon learn, "everyone"
was undeniably wrong.
Your Brain, Baby
What happened to Mrs. Grey's brain in those eighty-five years
between birth and death? And how did changes inside her brain affect
her cognitive abilities throughout life? How might she have steered
those changes in one direction or another--and to what end?
Mrs. Grey's story started the same way that Sara's had: with a tiny
clump of cells. I'll stick with the simple version of brain
development and aging, but even simplified it's an incredible tale.
Human life, after all, begins as one cell and ends with some hundred
billion in the brain alone.
We can start the story of Sara's brain by taking a peek inside her
mom's uterus at about the third week of gestation. Remember those
dividing cells? At about this time, some will form a column of cells
the shape of a tiny tube. At one end of the tube, cells will develop
into the spinal cord, while at the other end cells will develop to
form the brain's two hemispheres. Most of these cells become neurons
and at one end will have extensive branches--tens of thousands of
them--called dendrites, which will act as antennae to receive input
from other neurons. At its other end, each neuron will sprout a
single long extension called an axon, which in turn will sprout at
its tips tens of thousands of swellings called axon terminals.'
Within Sara's brain, these neurons will begin to send messages to
each other via electrical signals that "leap" from the axon terminal
of one neuron to a special docking site on the dendrite of another
neuron, crossing a gap called a synaptic cleft. Eventually the brain
will contain more than one hundred trillion such synaptic
connections.
選擇“Disable on www.wenxuecity.com”
選擇“don't run on pages on this domain”
