Welcome to
The Amazing Human Brain and Human Development
By Dr. Bruce D. Perry
http://www.childtraumaacademy.com/amazing_brain/index.html
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Contents
Lesson 1: Beginning with the Human Brain............................................................................................. 3
Lesson 2: Brain Organization and Function ........................................................................................... 10
Lesson 3: The Brain's Building Blocks .................................................................................................... 16
Lesson 4: Communication and Defense ................................................................................................ 20
Lesson 5: Plasticity, Memory, and Cortical Modulation in the Brain .................................................... 26
Lesson 6: Resources .............................................................................................................................. 32
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Lesson 1: Beginning with the Human Brain
A cross-section of the human brain.
Welcome
Welcome to The Amazing Human Brain. The lessons in this course will teach you how the
incredible mass of tissue in our skulls functions to make us the thinking, talking, feeling
creatures we are.
It is truly amazing that, at birth each child is born with a remarkable range of
potential. Neural systems that mediate emotional, social and cognitive functioning throughout
life, have yet to be organized. The organization, and functional capacity, of these systems is
determined by a combination of genetic potential and experience. The influence of
experience in expressing the potential of the brain is greatest in the first years of
life. Consistent, predictable, nurturing and enriched experiences help a child develop their
potential. This presentation will provide an overview of the key principles of
neurodevelopment which can help caregivers understand how we can create the environments
which express a child s potential or not.
Before we continue, here are our course objectives:
Course Objectives
1. Provide an overview of key principles of neurodevelopment crucial for understanding
the role of experience in defining functional and physical organization of the brain.
2. Describe the emerging clinical and research findings in maltreated children that
suggest the negative impact of abuse, neglect and trauma on brain development.
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3. Outline the clinical implications of a neurodevelopmental approach to child
maltreatment.
4. Discuss the role of public policy and preventative practices in context of the impact of
maltreatment on children's emotional, behavioral, cognitive, social and physical health
Now Think About It
Your brain weighs about three pounds. These three pounds, composed primarily of water and
fat, allow you to walk and talk, to laugh, cry, and touch, to love and hate, to create and
destroy. Everything you do, think and feel, every wish, dream, regret, and hope you
experience is mediated by your brain. By sensing the world around you -- storing some
fragment of each unique moment, cataloguing, sorting, organizing, and acting on your
experiences -- your brain defines you.
It is your brain that allows you to be connected to other human beings in the present. It is your
brain that links you to the past through language, religion, economies, and technologies -- all
of which essentially reflect the distilled experiences of thousands of generations of our
ancestors. And it is also your brain that connects you to the future if you have children and
pass elements of your own life experience to them through your example and teaching.
Finally, it is your brain -- and the brains of other people throughout history -- that has allowed
humankind to create what we know as humanity.
No Science Background Required
Throughout this course, I will provide you with information about the brain's structure and
function. This knowledge will create a framework for understanding the impact that
maltreatment or trauma may have on the developing child. Don't worry if you're not a
"science person." The majority of professionals working with maltreated children do not have
a background in biology or the neurosciences, either.
An understanding of the rudiments of human brain function and brain development can
provide very useful and practical insight to the all-too-often puzzling emotional, behavioral,
cognitive, social, and physical problems that caregivers, parents, teachers, and others face
when working with maltreated children.
Think about the following phenomena in the animal kingdom. What single explanation can
account for these amazing animal abilities?
·ð Sharks sense blood in water miles away.
·ð Dogs hear very high-pitched sounds.
·ð Geese navigate thousand-mile migrations, somehow sensing magnetic fields of the
earth.
·ð Hawks see the movement of prey from hundreds of feet in the air.
·ð Bears detect scents from miles away.
·ð Snakes sense body heat.
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You guessed it! Each one of these unique capabilities is mediated by the animal's brain. Their
brains' capacities to sense, process, and act are designed to help them survive -- to find food,
to avoid threat, to procreate, and to ensure the future of the species.
The human brain is programmed similarly. Without the unique properties of the brain,
humankind would have become extinct long ago. Our brain helps us survive and thrive while
we develop. Once mature, our brain allows us to create, protect, nurture, and teach the next
generation. Like the animal brains we just considered, the human brain is designed to help us
survive, procreate, and become caregivers.
Evolution Takes Time
Species evolve slowly. Human evolution is no exception. The structural and functional
capabilities of the human brain were selected to promote survival tens of thousands of years
ago. When the human brain was evolving, there were no computers, electricity, cars, books,
or even language, as we know it.
When the human brain was evolving into its current form, humans lived in "primitive" hunter-
gatherer bands of about 40 people. For 99 percent of the time that we have been Homo
sapiens, our ancestors lived in these very small groups. Nomadic migration, cooperative
hunting, and foraging for non-cultivated fruits and grains characterized human lives. It is in
these historical roots that the brain's key capabilities evolved and became modified and
refined in order to ensure the survival of the species.
Think of how human life has changed in the last 10-thousand years or so. The social
structures, economies, communications, technologies, and manifestations of abstract
creativity that now characterize human life were obviously not present when the human brain
was evolving. In many ways, the complexities of the modern world pose tremendous and
unfamiliar challenges to a human brain designed for a different world.
Despite its complexity, the brain maintains
some key actions. The brain senses,
processes incoming signals, stores elements
of this information and input, and acts on
the incoming information.
How information enters, and is processed by, your brain.
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Sense
In order to keep us alive, the brain uses a set of sensory organs (eyes, ears, nose, tongue, skin)
to tell us some of what is going on in the outside world. Remember, we can't hear like a dog,
smell like a bear, or see like a hawk. In fact, when compared to the rest of the animal
kingdom, human senses seem quite limited.
·ð Our ears hear sound only within a certain range
·ð Our eyes see light in the visual range but not infrared or ultraviolet light
·ð Our perception of touch requires a certain level of pressure
·ð Our sense of smell only helps us if a scent is powerful or nearby
Despite these limitations, our powerful human brains can still integrate the information from
all of our different senses and use it to create an internal representation of the external world.
Everything we experience is filtered by our senses. All sensory signals (sound, sight, taste,
touch) initiate a cascade of processes in the brain that alter brain structure and function. This
process of creating some internal representation of the external world (i.e., information)
depends upon the pattern, intensity, and frequency of neuronal activity produced by sensing,
processing, and storing signals.
Experience creates a processing template through which all new input is filtered. The more
frequently a certain pattern of neural activation occurs, the more indelible the memory
becomes. All living organisms have mechanisms to sense and respond to changes in their
environments. These mechanisms respond continually and are designed to keep our body's
systems in a state of equilibrium or homeostasis.
We have sensory mechanisms to tell the brain what is going on in the internal world of the
body. For example, we have special sensory apparatuses that tell the brain the concentration
of oxygen in the blood. Other systems sense the concentration of salts (e.g., too much salt
causes a sensation of thirst) or gases such as carbon dioxide. These internal sensory
mechanisms, like the five senses for the external world, help the brain continuously monitor
and act to maintain life.
Process
Once our sensory apparatuses have translated physical or chemical information from the
outside (or inside) world into neuronal activity, this set of signals travels up into the brain to
be processed. Sensory information from the external environment and the internal
environment enters the central nervous system at the level of the brainstem and midbrain.
As this primary sensory input arrives, it is matched against previously stored patterns of
activation. If the pattern is unknown, or is associated with previous threat, the brain will
activate a set of responses that are designed to help promote survival. (This alarm response is
at the heart of the post-traumatic symptoms seen in so many maltreated children.)
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Your Brain is Conservative
Throughout life, the brain is making
memories that correspond to various sights,
sounds, smells, tastes, and movements. It
creates templates of experience against
which all future experience is matched. In
this regard, the brain is a conservative
organ. It does not like to be surprised. All
unknown or unfamiliar environmental cues
are judged to be threatening until proven
otherwise.
Therefore, what you recognize as safe and
comfortable has only become so through
your experience. Something in your safe
and comfortable present moment matches
the associated, stored memories of previous
safe, pleasing, or rewarding experiences.
The same theory applies to feelings of terror
or threat.
The human brain, divided into its four interconnected areas.
Sensory integration (putting the sight, sound, smell, and feel of an event together) is a crucial
step in healthy development. There can be disruption of this capacity by even minor "timing"
errors. If the signals coming from the neural systems responsible for hearing do not get into
the thalamus and cortex in a synchronous way, there can be confusion, disorganization, and
abnormal functioning. (See sidebar.)
Incoming Signal
At each level of brain organization, the incoming signal (called afferent) is categorized. When
the brain compares incoming information to previously stored patterns, mistakes sometimes
occur. For the Vietnam vet, a loud firecracker can induce a startled response and anxiety even
though he knows it is only a firecracker. The incoming loud sound is categorized in the
brainstem as being previously associated with threat and danger even before the signal can get
to the cortex.
At each level of processing, a categorization process takes place. This immediate, localized
processing can be crucial for survival. Your brainstem and spinal cord will tell you to
withdraw your hand from a fire even before your cortex knows that you have been burned.
Another key step in processing experience is organizing information. Because the brain
cannot possibly create a unique neural imprint or pattern of change to store every element of
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every experience, the brain stores "template" patterns based upon the first set of organizing
experiences. All future incoming input is matched against these stored templates and, if
sufficiently different from the original pattern, the brain will create a memory reflecting that
difference.
Store
Inherent to the processing of information coming into the brain is the capacity to store
elements of these incoming signals. At the heart of our survival neurobiology is the capacity
to make and store internal representations of the external world. Internal representations are
your memory. The ability of the brain to create memories is due to the capacity of neurons
and neural systems to change from one homeostatic state to another. Neuron and neural
system changes are "use-dependent," only occurring if a new or extreme situation forces
them.
This has important implications for understanding how we "create" memories of traumatic
experiences. For adults, most experiences have only a small component that is new or unique.
Typically, the majority of places, faces, words, sounds, smells, tastes, etc. in any given
moment are familiar. In the classroom, for example, a lecture may result in cortical activation
but will cause little new emotional, motor, or arousal activity.
Act
You will recall that the neuronal pathways sending signals into a brain area are called
afferent. The pathways sending neuronal signals out are called efferent. These efferent
pathways regulate actions resulting from the process of sensing, processing, and storing
incoming signals. Your brain mediates and controls the actions of your body. By regulating
and directing the activities of the neuromuscular, autonomic, endocrine, and immune systems,
your brain controls your every move.
Coming Up
Stay tuned for Lesson 2, where we'll learn about brain organization and parts like the cortex,
and who MacLean was in the world of the brain.
Again, don't hesitate to use the Message Board for any questions you come up with as we
move through the course. It's not every day you'll read about, say, the medulla , and not at all
surprising that you might have questions about it.
A Brainy Factoid
You probably wouldn't be surprised to learn that the largest brain on earth belongs to
the gigantic sperm whale, weighing in at a massive 20 pounds. But consider that the
human brain, at a measly three pounds, is still approximately two percent of a
person's body weight. The poor sperm whale (who cannot take brainy courses on the
Internet) has a brain that represents only 0.02 percent of its weight!
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The Brain's Prime Directives
Our brain's design makes it possible for us to survive, procreate, and become
caregivers. These three prime directives have ensured the continuation of our
species.
Sensory Integration Dysynchrony
Imagine watching a poorly dubbed foreign film. It's disorienting, isn't it? That's
because the sound and movements don't match. It is likely that several
developmental disorders include elements of sensory integration problem. Indeed,
many infants and young children with these problems have a terrible time with lots of
noise, chaos, action -- they become overloaded and may hold their hands over their
ears, crawl into the fetal position, yell, or initiate self-soothing behaviors (e.g.,
rocking).
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Lesson 2: Brain Organization and Function
In our last lesson we talked about brain basics: our brain as a sensory organ, how it has
evolved over time, and what its prime directives are. This time we'll delve into how our brains
are organized, and talk about some of the key functions of those major areas.
It's Complex
In order to perform all of the key actions we discussed in Lesson 1, the brain has evolved into
a wonderful and highly functional structure. As you have already learned, the brain is not just
one homogeneous mass of tissue, but a complex and hierarchical organization. Parallel
systems exist to mediate various distinct functions. In general, the complexity of brain
structure and the functions that these different structures mediate are organized in a bottom-
to-top organization.
The bottom line is that the brain has lots of parts. For the purposes of this course, I will divide
the brain into four major areas: brainstem, diencephalon, limbic, and neocortical. This, of
course, is not the only way to divide the brain. Before examining the four major areas in our
chosen model, let's spend a few moments exploring some of the other ways that the brain can
be broken into component parts.
MacLean's Triune Brain Model
In one of the most original and useful ways of understanding the human brain, Paul MacLean,
a pioneer of modern neuroscience, has defined three distinct systems within the brain that
correspond to key evolutionary systems that have developed across various species. This
model is known as the Triune Brain model.
The Triune Brain model defines the lower, less complex areas of the brain as being similar in
structure and function to the reptilian brain (hence his term the R-complex). Take a minute to
look at the table below to see how he has organized the four areas of the brain that we will
focus on in this lesson. These areas are uniquely organized in primates.
MacLean's Triune Brain
Name Part(s)
Neomammalian Neocortex and key thalamic nuclei
Limbic cortex and associated limbic
Paleomammalian system including amydala and
hippocampus
Caudate nucleus, putamen, globus
Protoreptilian or
pallidus and associated brainstem
R-Complex
inputs
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More Models
The other more common approaches to the division of the human brain are outlined in the
table below. In the most simple, there are three divisions: hindbrain, midbrain, and forebrain.
The developmental style of dividing is based upon the developmental heritage of the given
constituent parts. (You'll find the four-part model of division that we're using in this course at
the far left-hand column of the table.)
The key observation in organizational process is that, in all cases, the brain has a hierarchical
organization, with the lowest complexity at the bottom and highest on top. The most complex
part of the brain is the cortex. When examining genetic homology across species, the frontal
cortex (part of the neocortex) is the most "uniquely" human.
Matching the physical hierarchical structure is a hierarchy of function. The lower brainstem
areas mediate the simplest regulatory functions, while the neocortex mediates the most
complex. The key thing to remember here is that different brain areas and systems mediate
different functions. This will be important when trying to understand the changes in
emotional, behavioral, and cognitive functioning that take place when someone is threatened.
Now let's return to the organization model of the brain, which I had told you we'll use in this
course. Do you remember the four major areas? I'll refresh your memory! They are the
neocortical, brainstem, diencephalon, and limbic regions.
Complexity of brain function, in ascending order.
Brain Organization and Function
The neocortex is made up of several sections. Use the figure 3 to reference these sections as
you read more about them.
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Functional Developmenta Primary
Constituent Parts
Division l Division Division
Cerebral cortex
Frontal Lobes
Temporal Lobes
Neocortex
Parietal Lobes
Occipital Lobes
Corpus Callosum
Cerebral
Telencephalon Hemisphere
Limbic
Amygdala
s
Cingulate Forebrain
Hippocampus
Cortex
Basal ganglia
Amygdala
Caudate Nucleus
Hippocampu
Putamen
s
Globus Pallidus
Septum
Diencephalo Thalamus Diencephalo
Diencephalon
n Hypothalamus n
Midbrain
Midbrain
Superior
Colliculus
Inferior Colliculus Mesencephalo
Brainstem Brainstem
Cerebellum n
Pons
Hindbrain
Medulla
Oblongata
Spinal Cord Spinal Cord Spinal Cord
Cerebral Cortex
The largest part of the brain is called the cerebrum, which comprises about 90 percent. The
word cerebrum, in fact, comes from the Latin word for brain. The cerebral cortex is actually
the gray, wrinkled surface encompassing the cerebrum. The cerebral cortex looks wrinkly
because of its many folds.
Although it is about as thick as corrugated cardboard, if you laid it out flat, the cerebral cortex
could almost cover the top of your kitchen table. There are 10-to-14 billion neurons contained
within the cerebral cortex, a whopping number when you consider that the world's human
population is less than that!
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Cerebral Lobes
Nestled beneath the cerebral cortex are the central lobes of the brain. There are four of them,
and they are responsible for critical daily activities such as hearing, vision, speech, and
executive function.
The frontal lobe is divided into four functional areas:
1. The primary motor cortex is involved in the initiation of voluntary movements. It is
composed of the precentral gyrus.
2. The premotor area is made up of the remainder of the precentral gyrus and is also
important in the initiation of voluntary movements.
3. Broca's area, located primarily in the left cerebral hemisphere, is important in the
production of speech and written language.
4. The prefrontal cortex comprises the remainder of the frontal lobe. It is involved in
what may be described as personality, insight, and foresight.
The parietal lobe is associated with three functions:
1. The postcentral gyrus is concerned with the initial cortical processing of tactile and
proprioceptive (sense of position) information.
2. Much of the interior parietal lobule of one hemisphere (generally the left), together
with portions of the temporal lobe, is involved in the comprehension of language
(Wernicke's Area).
3. The remainder of the parietal cortex subserves complex aspects of orientation of the
individual in space and time.
The temporal lobe is associated in general with three functions:
1. A small area of the temporal lobe is the primary auditory cortex.
2. The parahippocampal gyrus and hippocampus, as part of the limbic system, are
involved in emotional and visceral responses.
3. The temporal lobe is involved in complex aspects of learning and memory recall.
The occipital lobe is more or less exclusively concerned with visual functions. Primary visual
cortex is contained in the walls of the calcarine sulcus and some of the nearby cortex. The
remainder of the lobe is referred to as a visual association cortex that is involved in higher-
order processing of visual information.
Still More Cerebral Cortex
The cerebral cortex also contains major internal structures (some of which you've probably
heard of) such as the:
·ð Forebrain: credited with the highest intellectual functions of thinking, planning, and
problem solving
·ð Hippocampus: involved more directly in memory formation and retrieval
·ð Thalamus: serves as a relay station for virtually all the information coming into the
brain
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·ð Hypothalamus: contains neurons that serve as relay stations for internal regulatory
systems, monitoring information coming in from the autonomic nervous system
Brain Organization and Function
The diencephalon has four main substructures: thalamus, hypothalamus, epithalamus, and
subthalamus. We'll focus on the first two.
In Latin, thalamus means little room. In the brain, the thalamus is located deep inside and
between the two cerebral hemispheres, so it is indeed a little room. The thalamus is a nuclear
mass of great importance in both sensory and motor systems. No sensory information, with
the exception of olfactory information, reaches the cerebral cortex without first passing
through and being processed by thalamic nuclei.
The thalamus functions as a way station between the brain and the spinal cord. If you
experience sensations such as pain, pressure, or temperature, you have your thalamus to
thank! Senses such as taste, sight, sound, and touch also must pass through the thalamus as
they make their first stops in the brain.
The prefix hypo means under, so consider the hypothalamus as being located under the
thalamus. In medical lingo, the hypothalamus is referred to as inferior to the thalamus. The
lower, or inferior, surface of the hypothalamus is actually one of the very few parts of the
diencephalon visible on an intact brain. (Remember, the thalamus is the inner room.)
The hypothalamus is tiny, about the size of a small bean, and comprises about 1/300th of the
brain's total weight. Despite its unimpressive size, the hypothalamus is the major visceral
control center of the brain. It is your hypothalamus that regulates your body temperature. And
it is your hypothalamus that sends you a signal to let you know that you're hungry, thirsty,
tired, mad, or sad. The hypothalamus is involved in limbic system function as well.
The brainstem is located below the thalamus and the hypothalamus. The brainstem is about
three inches in length and is about as big around as a thumb. The brainstem is divided into the
midbrain, the pons, and the medulla.
At the top of the brainstem is the midbrain. The midbrain is the portion of the brain that
adjusts the sensitivities of your ears to noises and your eyes to light.
Beneath the midbrain is the pons, a term that means bridge. The pons functions as a conduit
between the brain and the spinal cord and is composed mainly of bunches of nerve fibers that
connect the cerebral cortex with the cerebellum and the spinal cord. Your pons controls
sleeping and dreaming functions.
The medulla is only about an inch long and connects the brain to the spinal cord. It is the
medulla that regulates many of the things you do without thought that are critical to your
existence, such as heartbeat, breathing, and swallowing. Just think how complicated life
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would be if every time you had to swallow, you had to focus on the act and will it to happen!
The medulla also controls your brain's vomiting center.
Coming Up
Whew! We just covered a tremendous amount of information. Learning about how the human
brain is organized is interesting to most people for a simple reason: we all have one. Knowing
where in your brain the things you do during the day are directed from adds interest to some
of the most mundane things we do.
Let's stay in touch on the Message Board. How will knowing more about the human brain
help you?
Do You Remember the Brain's Key Actions?
Remember: the brain senses, processes, stores, and acts.
What Does Homologous Mean?
Two things that are homologous correspond to each other, or are similar in position, value, structure,
or function. In biological terms, homologous parts (organs, limbs, etc.) are similar in structure and
evolutionary origin, although not necessarily in function. For instance, the flippers of a seal and the
hands of a human being are homologous.
Another Brainy Factoid
The sperm whale may triumph by having the biggest brain, but who wins the pea-brain competition?
Stegosaurus, also known as the "plated lizard," roamed the United States 150 million years ago and
weighed in at a mighty two tons. And how large was the massive brain that this creature needed to
orchestrate its existence? Smaller than a ping-pong ball!
Thalamus or Hypothalamus?
Experiencing sensations such as pain or pressure? That's the job of your thalamus. Feeling hungry,
tired, or irritable? Your hypothalamus is busy sending you those types of signals.
Thanks, Brainstem!
It is the brainstem that controls reflexes. When you instantly recoil from momentary contact with the
heat of a whistling teapot, you have your brainstem to thank for your quick reaction. If you had to take
the time to consciously think about how to react to the pain of heat, your burn would be much worse!
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Lesson 3: The Brain's Building Blocks
Lesson 2 taught us about the major sections of the brain and what their primary functions are.
Lesson 3 is going to take you deep into the structural units of the brain, to the neurons and
cells.
If you are feeling even slightly confused about some information, don't hesitate to go back
and reread the previous lessons, or log on to the Message Board and ask about it.
Parts in the Trillions
The brain is an amazingly complex organ. Indeed, it is the most complex biological organ in
the known universe. It is composed of trillions of "moving parts" -- the cells of the nervous
system.
The basic structural units of the human brain are cells. The brain is made of two major types
of specialized cells, neurons and glial cells. Neurons, as you may recall from your high school
biology class, are cells that specialize in receiving and transmitting signals.
Each cell, whether neuronal or glial, possesses a cell wall. The cell wall is a membrane that
separates the inside (intracellular) components of the cell from the outside (extracellular)
environment of the cell. It is inside of these that we store our genetic material -- genes. In
each cell, at any given moment, only small portions of our genes are being activated and
producing proteins, while the rest remains unexpressed in that cell. Amazingly, each of the
100 billion neurons and one trillion glial cells of the brain contain the exact same genetic
material, the same genes. And more amazing, each of these cells expresses a unique pattern of
gene activation that is a reflection of the cell's history and current environment.
This is one of the miracles of biology. Each cell will produce those genetic products that it
needs to do its specific "job." And, in ways we have yet to fully understand, billions of cells
can coordinate, orchestrate, communicate, and work together to create the most complex of
biological machines from these billions of "moving parts" -- a human being.
Neurons are cells specialized to receive, store, and transmit information. The business of
neurons is communication. All neurons have special structural features that allow neurons to
"communicate" -- to receive, process, store, and send "information" that comes from their
outside (extra-cellular) world.
Specialized structural and biochemical properties allow neurons to receive a stream of
chemical signals from other neurons, process these incoming "messages," change their
chemical interior in response to these signals (and thereby, store important information), and
then transmit the summed signals to other neurons. Chains of neurons engaged in continuous
dialogue and communication create the functional systems that allow the brain to mediate and
control a host of remarkable activities.
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There are hundreds of "types" of neurons. They can either be classified by unique structural
properties (i.e., how they look) or by unique functional properties (i.e., what they do).
Neurons that are directly involved in the transduction of physical or chemical signals from
sense organs are called sensory neurons. Motor neurons end directly on muscles or glands.
Interneurons, not surprisingly, interconnect other neurons.
In some areas of the brain, neurons are densely packed, while in others they are relatively
distant. Most neurons form their connections with neurons that are physically adjacent. Other
neurons send axons to neurons in distant areas of the brain. These are called extrinsic neurons.
Extrinsic neurons tend to form groups or clusters called nuclei. A single neuron or group of
neurons can send simultaneous signals to many areas. These nuclei play important roles in the
orchestrating and coordination of communication.
The neuron is one of two types of specialized cells that make up the human brain.
Glia are also specialized cells and outnumber neurons 10 to one. The glial cells work to
nourish, support, and complement the activity of neurons in the brain. They do not carry
messages themselves, but instead ensure that the neurons do their jobs unimpeded. Glia
supply neuronal nutrients and other chemicals, and are also responsible for attacking harmful
bacteria. Recent studies suggest that glial cells also play an important role in communication.
Because there are different types of neurons, it makes sense that there are also different types
of glial cells. For each type of neuron, there is a corresponding glial cell designed to perform
its "supporting role." Some glial cells form myelin sheaths (which are fat wrappings, like
insulation) around axons that allow the axons to conduct information more rapidly.
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Synaptic Transmission
Whereas neurons and glial cells are the "building blocks" of brain structure, neuron-to-neuron
communication is the basic unit of brain function. It is quite astonishing to think that the
memory of a loved one's face or the capacity to create a new loving bond is created by some
dynamic pattern of synaptic activation. In other words, your fond memories of the comfort of
Grandma Hilda's cozy lap and the taste of her banana pudding are the result of chemicals in
your brain being zapped around amongst a bunch of neurons.
There are tiny spaces between the point where one neuron ends and another neuron begins.
This infinitesimally small area is called the synapse. Here is where cells use chemicals to fire
messages to one another. Think of each synapse in the brain as a one-way street. The signals
always pass in the same direction; they never work in reverse!
Coming Up
We're halfway through the course already. How did you do this week? Have you started
thinking about how various areas of the brain are affected by different types of trauma
suffered by children? Log on to the Message Board and tell us some connections you've
made.
In Lesson 4 we'll learn more about how different parts of the brain respond to trauma and how
human communication has evolved over time.
A synapse is the tiny space between neurons in which cells send chemical messages to one another.
What's an Axon Anyway?
The axon is a tiny fibrous extension of the neuron. An axon looks like a tail on the neuronal cell. It is
the axon's job to facilitate the neurochemical transmissions that allow communication from neuron to
neuron. Axons are extremely thin but can be incredibly long. Some axons reach all the way from the
spinal cord to the feet.
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Glia Get a Bad Rap
Although glia compose 90 percent of the cells in the brain, there are no gliosciences. You've never
heard of a gliologist, have you? That's because there is no such thing. We only have the
neurosciences and neurologists.
Synaptic Neurotransmission
A continuous dynamic of synaptic neurotransmission allows the brain to do all of its remarkable
activities. When you hum a song, do a little dance, smile as you remember a joke, speak any
language, or feel your heart race as you anticipate seeing someone you love, you are using your
brain's capacity to store experience. And all of that is allowed and mediated by synaptic
neurotransmission.
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Lesson 4: Communication and Defense
Welcome to Lesson 4 of the Amazing Human Brain. Communication is a complicated process
that has taken many, many years to evolve. Now that you've spent the first three lessons
learning about the fine points of the physical brain, you'll learn how the brain operates
something as intangible as communication.
We will also talk about how different parts of the brain respond to trauma. I asked you to log
on to the Message Board with your thoughts about this in Lesson 3. Let's see how close you
were.
Humans are Special
Communication between one human and another is the hallmark of our species.
Communication was the critical capacity required for survival during the thousands of
generations of our evolution. Naked, slow, weak, and without biological armor or weapons,
humans survived by living and hunting in groups. Interdependent individuals created a strong,
flexible, and adaptive "whole" -- the band, the clan, the tribe.
While physically separate and self-aware, individual humans are linked by the invisible bonds
of sensation, perception, and communication into larger biological units, or groups. One
individual may belong to many groups -- a couple, a family, and a working group. Each group
has a unique set of tasks and a set of rewards for its members. The integrity and function of
the group is formed, maintained, and changed by social interaction.
The human brain developed remarkable biological apparatus dedicated specifically to social
perception and communication, verbal and non-verbal. These underlying biological properties
are continually at play in all human interactions -- sensing, processing, perceiving, storing,
and acting on signals from other humans. All human interactions are governed by core
principles of communication that are the product of neurobiological processes shaped by
thousands of years of evolutionary pressures.
Through the evolutionary process, the remarkable expressive communication capacity of the
face was further refined. In fact, facial expression became the most important of all social
communication instruments. What else has the capacity to both reflect the internal emotional
state of the individual and elicit a specific emotional and social response? The various faces
we make can express the full range of human emotions.
Beware of Strangers
During their development, each person creates a catalogue of familiar faces and stores these
as templates for familiar/safe. In these familiar faces, the infant and child learn the non-verbal
language of the group as surely as they learn the verbal language. An unfamiliar face will
elicit a low-level alarm response in any individual. All new faces are judged to be threatening
until proven otherwise.
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Two factors provoke this reaction. First, the brain's information matching process is very
conservative. All novel situations and new information are judged to be threatening until
proven otherwise. The second specific reason that new faces elicit a low-level alarm is that
the human brain evolved in a world where, for thousands of generations, the major threats to
any individual were other humans.
A new person, a new face in the typical interaction from our history meant that there were
other humans around competing for the same water, fruits, game, and cave. This new person
was as likely to attack as he was to decide to affiliate or cooperate. Across generations,
wariness to new individuals, new groups, and new ideas was selected and built into the
circuits of the human brain's alarm response.
Mismatching and Human Behaviors
Templates for faces and facial features of same/safe/familiar, like all other templates for
emotional, behavioral, and social functioning, are set during childhood. The tendency to have
an alarm response when exposed to an unfamiliar face or mismatched facial features is at the
root of many human behaviors.
Despite very minor differences in facial feature placement, almost all people can immediately
recognize a Down syndrome child. This matching against previous template faces is at the
root of racism (and is a strong argument for placing children of different races together in
school and play, allowing them to acquire a diverse set of internal templates for what is
same/safe/familiar).
This capacity to match diverse information against previous templates of multi-sensorial input
is also at the root of the recognition of deceit. When words do not match body movement,
facial expression, or the tone of voice, the brain "senses" a multi-sensory mismatch.
When someone says, "I love you," there are accompanying non-verbal signals validating the
verbal information, such as eye contact or facial expression. The same can be said of someone
who is telling the truth. Children raised with caregivers who "talk the talk" but don't "walk the
walk" (e.g., those exposed to domestic violence or multiple foster homes) internalize patterns
of communication and interaction that are distorted and often destructive. This is also how a
child learns the mismatched association between intimacy, power, violence, and threat.
Through thousands of generations of evolutionary selection the brain developed its amazing
capacity to read non-verbal cues, many of which are communicated via changes in facial
expression. The brain has special face and expression recognition capabilities and, through a
process of "matching" expressions and faces with existing templates, makes decisions about
the familiarity and intent of the specific interaction.
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Secondary Cues to Template Recognition
Because we have a limited capacity for categorizing and matching specific faces and facial
expressions, the brain utilizes other cues to make decisions about potential friends and
enemies. Characteristics such as body movements, postures, or other symbolic trappings of
recognition, such as clothes, uniforms, or style of haircut, are used to make secondary
decisions about recognition. You may not recognize the face, but the haircut, clothes, or
manner of interaction can readily identify someone as "familiar/good" or as "familiar/bad."
This categorizing tendency is the basis for a host of well-described and common phenomenon
in human interaction -- including first impressions or using "known" celebrities to sell
products or ideas. A classic example of this in the mental health field is transference. This is
the phenomenon of attaching multiple attributes of a past relationship to one in the present
when only one of those attributes may truly be present (e.g., reacting to a male therapist with
the intensity that was present in a paternal relationship).
Children raised in deceitful settings easily lie without detection. They have not internalized
the same non-verbal templates associated with deceit as the rest of society has. For these
children, the development of sociopathic characteristics is merely an adaptation to the
deceitful, inconsistent, and unrewarding world their caregivers have created for them.
A terrified three-year old child huddles, sobbing, in a dark corner of his room after being
beaten by a drunken parent for spilling milk. A colicky infant cries for eight hours, left alone,
soiled and hungry, by an immature, impaired mother. A seven-year old boy watches his father
beat his mother, the most recent of many terrorizing assaults this child has witnessed in his
chaotic, violent household.
Terror, chaos, and threat permeate the lives of too many children. Millions of children across
the globe each year have tiny pieces of their potential chipped away by fear. When fear is
omnipresent, it changes the child. These powerful experiences work to literally change the
brain of a frightened child. Fear inhibits exploration, fear inhibits learning, and fear inhibits
opportunity.
In order to understand what is happening inside these children, we need to continue our study
of the basic organizational and functional properties of the human brain. We've already
covered some of the core elements of brain structure and organization that serve as a
background for this lesson. Now, let's turn our attention toward some of the key features of
the brain that are directly influenced by trauma, neglect, or fear.
In order to understand the traumatized child, we must first understand the fear response. The
human brain has a very elaborate and important set of neural systems involved in the response
to threat. The abnormal persistent activation of these systems appears to lead to many of the
symptoms seen in maltreated children. We'll begin, then, by examining the key brain systems
regulating the stress response.
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Neurotransmitters and The Stress Response
There are many neurotransmitters involved in the stress response. Some of the most important
neurotransmitters are released from clusters of extrinsic neurons. These systems have
disproportionate power to regulate human behavior, emotional functioning, and cognition.
This is because these systems originate in the brainstem and have connections in virtually all
brain areas. The brainstem regulates and mediates hundreds of crucial functions -- including
the complexities of the stress response.
The Reticular Activating System (RAS)
The RAS originates in the brainstem and is a network of ascending, arousal-related neural
systems. The RAS plays a major role in arousal, anxiety, and the modulation of limbic and
cortical processing. These brainstem and midbrain monoamine systems, working together,
provide the flexible and diverse functions necessary to modulate the variety of functions
involved in anxiety regulation.
Locus Coeruleus
The locus coeruleus (LC) is a critical brain stem nuclei involved in initiating, maintaining,
and mobilizing the total body response to threat. The LC plays a major role in determining the
value of incoming sensory information, increasing in activity if the information is novel or
potentially threatening. Acute stress results in an increase in LC activity. The LC plays a
critical role in regulating arousal, vigilance, affect, irritability, locomotion, attention, the
response to stress, sleep, and the startle response.
Hippocampus
The hippocampus is critical to the process of learning. It takes short-term memory and
converts it into long-term memory. It plays a major role in memory, including what we call
episodic, declarative, and spatial learning and memory. The hippocampus also plays a key
role in various activities of the autonomic nervous and neuroendocrine systems.
Stress hormones and stress-related neurotransmitter systems have the hippocampus as a
target. Various hormones (e.g., cortisol) appear to alter hippocampus synapse formation,
thereby causing actual changes in gross structure and size. Repeated stress inhibits the
development of neurons and atrophy of the hippocampus can occur. These neurobiological
changes are related to some of the problems with memory and learning found in stress-related
neuropsychiatric syndromes, including post-traumatic stress disorder (PTSD).
Amygdala
In the recent past, the amygdala has emerged as the key brain region in the processing,
interpreting, and integration of emotional functioning. The amygdala is where fear learned
from past experience is permanently stored. In the same fashion that the LC plays the central
role in orchestrating arousal, the amydgala plays the central role of processing afferent and
efferent connections related to emotional functioning.
The amygdala receives input directly from sensory systems throughout the brain. The
amygdala processes and determines the emotional value of simple sensory input, complex
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multisensory perceptions, and complex cognitive abstractions. The amygdala orchestrates the
response to this emotional information by sending projections to brain areas involved in motor
(behavioral), autonomic nervous system, and neuroendocrine areas of the CNS.
Cortex
The quality and intensity of any emotion, including anxiety, is dependent upon subjective
interpretation or cognitive appraisal of the given situation. How an individual cortically
interprets the limbic-mediated activity (i.e., their internal state) associated with arousal plays a
major role in the subjective sense of anxiety.
Kluver-Bucy syndrome, the result of damage to or surgical ablation of temporal lobes, results
in loss of fear for current and previously threatening cues. The general lack of inhibition
demonstrated by this syndrome suggests a loss of the capacity to recall cortically stored
information related to previous threat, or to efficiently store threat-related cues from new
experience.
Other areas of the cortex play a role in threat. Foremost among these are the primary and
multimodal association areas, which have direct connection to the amygdala.
Coming Up
We covered an enormous span of material in this lesson. How are you doing? I expect many
questions to come up from this lesson, and I cannot urge you enough to use the Message
Board for them. Your questions and thoughts will undoubtedly help shed light on the subject
for others in the class. I look forward to seeing them.
In the next lesson, we're going to learn how the brain stores experience and how it is changed
by those experiences.
I Understand
Central to the invisible biological processes that allow social interaction is communication -- the
capacity to perceive and understand others and to express meaning and intention to others. Just as
there are parts of the brain responsible for moving, seeing, or hearing, there are systems in our brains
dedicated to social affiliation and communication.
Yet Another Brainy Factoid
Although we do have the gift of language, we are not unlike non-human primates when we resort to
"hollering" and beating our chests. While humans rely on their words to impart intent, our non-verbal
communication (mostly mediated by our faces) is still our primary form of communication. Think about
it. How often have we all experienced this -- rolled eyes ever so slightly with the smallest down turn of
the mouth at the same time their words say, "Oh, that sounds good." Now what do they really mean?
We humans use words to conceal as much as we use them to reveal.
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Important Neurotransmitters in the Cortex
Do you remember what a neurotransmitter is? It is the chemical that a neuron releases in order to
relay information to another cell.
Important neurotransmitters in cortical regions are GABA and glycine. The capacity of
benzodiazepines to alter arousal and sensitivity to threat has long been known. The principle
pharmacological treatment for many anxiety disorders involves benzodiazepine treatment, targeting
GABA receptor complexes.
Scientists Demonstrate Key Role of Amygdala in Emotional Memory
The site of perception of anxiety is likely to be the amygdala. In experiments with laboratory rats,
scientists have determined that a rat without an amygdala has no fear of cats! When the "storage bin"
for emotional information is missing, the emotion is lost.
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Lesson 5: Plasticity, Memory, and Cortical Modulation in the Brain
Welcome back. Last time we talked about how human communication works in relation to the
brain and also how different parts of the brain are affected by traumatic experience.
This week we'll go a little deeper to discuss how the brain stores those experiences and how it
adapts as a result of them.
Plastic Fantastic
The human brain is very plastic, meaning that it is capable of changing in response to
patterned, repetitive activation. Reading, hearing a new language, and learning a different
motor skill such as typing are all examples of the brain's plasticity in action. But not all parts
of the brain are equally plastic.
As areas of the brain increase in complexity, they become more
plastic.
The Cortex Is the Most Plastic
The malleability of specific human brain areas is different. The most complex area of the
brain -- the cortex -- is the most plastic. We can modify some cortex-related functions
throughout life with minimal effort. For example, even a 90-year-old person can learn a new
phone number.
The lower parts of the brain, which mediate core regulatory functions, are not very plastic.
And that is for good reason. It would be very destructive for these basic and life-sustaining
functions to be easily modified by experience once they were organized. A lesion that kills
one million neurons in the cortex can be overcome. For instance, people recover language and
motor skills following a stroke. Conversely, a lesion in the brainstem that killed as many cells
would result in death.
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Brain Plasticity Is Related to Two Main Factors
The degree of brain plasticity is related to two main factors: the stage of development and the
area or system of the brain. Once an area of the brain is organized, it is much less responsive
to the environment, or plastic. A critical concept related to memory and brain plasticity is the
differential plasticity of various brain systems.
The brain changes in a use-dependent fashion. All parts of the brain can modify their
functioning in response to specific patterns of activation -- or to chronic activation. These use-
dependent changes in the brain result in equivalent changes in cognition. This is what we
recognize as cognitive learning. Similarly, emotional functioning (social learning), motor-
vestibular functioning (e.g., the ability to write, type, ride a bike) and state-regulation capacity
(e.g., resting heart rate) all exemplify the brain's ability to make use-dependent changes.
Conversely, you cannot change any part of the brain that you are not activating! No one could
learn to play golf by sitting in a classroom and listening to Tiger Woods talk about how to
shoot a low score. In order to learn -- to change the brain -- the experience has to activate the
part of the brain that mediates the function you are trying to learn; the right parts of the cortex
must be activated and receptive to learn traditional "cognitive" concepts such as we teach in
schools, for example.
A mismatch between modality of teaching and the receptive portions of a specific child's
brain can occur. This is particularly true when considering the learning experiences of the
traumatized child. Classroom learning cannot occur if the child is in either a persistent state of
arousal and anxiety, or of dissociation. When in this state, the key parts of the cortex are not
receptive to cognitive information that is not relevant to survival. The traumatized child's
brain is essentially unavailable to process efficiently the complex cognitive information being
conveyed by the teacher.
Trauma Impairs Interpretation
The traumatized child frequently has significant impairment in social and emotional
functioning. Hyper-vigilant children frequently develop remarkable non-verbal skills in
proportion to their verbal skills (street smarts). They often over-read (misinterpret) non-verbal
cues. Eye contact is read as a threat, or a friendly touch is interpreted as an antecedent to
seduction and rape. These assessments might have been accurate in the world they came from.
During early development, these traumatized children spent so much time in a low-level state
of fear that they were focused primarily on non-verbal cues. Once out of such an environment,
it is still difficult for the child's brain to interpret (relearn) these innocent looks and touches as
benign.
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These children are often labeled as learning disabled. These difficulties with cognitive
organization contribute to a more primitive, less mature style of problem solving -- with
violence often being employed as a "tool."
This principle is critically important in understanding why a traumatized child -- in a
persistent state of arousal -- can sit in a classroom and not learn. The brain of this child has
different areas activated -- different parts of the brain controlling his functioning. The
capacity to internalize new verbal cognitive information depends upon having portions of the
frontal and related cortical areas activated, which in turn requires a state of attentive calm.
Sadly, this is a state that the traumatized child rarely achieves.
Various developmental stages as they pertain to the brain and behavior.
The above table illustrates the various developmental stages as they pertain to the brain and
behavior. Note that when a child is threatened, he or she is likely to act in an "immature"
fashion. Regression, a retreat to a less-mature style of functioning and behavior, is commonly
observed in all of us when we are physically ill, sleep-deprived, hungry, fatigued, or
threatened. When we regress -- in response to a real or perceived threat -- our behavior is
mediated (primarily) by less-complex brain areas.
Baseline State of Arousal
If a child has been raised in an environment of persistent threat, the child will have an altered
baseline such that the internal state of calm is rarely obtained. The traumatized child will have
a "sensitized" alarm response, over-reading verbal and non-verbal cues as threatening. This
increased reactivity will result in dramatic changes in behavior in the face of seemingly minor
provocative cues. Often, over-reading of threat will lead to a "fight or flight" reaction and
impulsive violence. The child will view his violent actions as defensive.
Children exposed to significant threat will "re-set" their baseline state of arousal such that
even when no external threats or demands are present, they will be in a physiological state of
persistent alarm. As external stressors are introduced (e.g., a complicated task at school, a
disagreement with a peer) the traumatized child will be more "reactive." Even a relatively
small stressor can instigate a state of fear or terror. The cognition and behavior of the child
will reflect his or her state of arousal.
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No part of the brain can change without being activated. You can't instruct someone in the
French language while they are asleep, nor can you teach a child to ride a bike by drawing a
picture on a blackboard.
The increased baseline level of arousal and increased reactivity in response to a perceived
threat plays a major role in the various behavioral and cognitive problems associated with
traumatized children.
The human brain works through inhibitory mechanisms. The majority of the brain's structural
organization takes place in childhood. This development is characterized by both sequential
development and "sensitivity" (from the brainstem to the cortex), and by the "use-dependent"
organization of these various brain areas.
As the brain grows and organizes, the higher, more complex areas begin to control and
modulate the more reactive, primitive functioning areas of the lower parts. The person
becomes less reactive, less impulsive, and more thoughtful. Any factors that increase the
activity or reactivity of the brainstem (e.g., chronic traumatic stress) or decrease the
moderating capacity of the limbic or cortical areas (e.g., neglect, brain injury, mental
retardation) will increase an individual's aggression, impulsivity, and capacity to be violent
(see the graphic below).
Cortical Modulation Is Age-Related
The capacity to moderate frustration, impulsivity, aggression, and violent behavior is age-
related. With sufficient motor, sensory, emotional, cognitive, and social experiences during
infancy and childhood, the mature brain develops (in a use-dependent fashion) a mature,
humane capacity to tolerate frustration, contain impulsivity, and channel aggressive urges.
A frustrated three-year-old (with a relatively unorganized cortex) will have a difficult time
modulating the reactive, brainstem-mediated state of arousal and will scream, kick, bite,
throw, and hit. However, the older child, when frustrated, may feel like kicking, biting, and
spitting, but has "built in" the capacity to modulate and inhibit those urges.
As the brain develops and the more complex areas
organize, they begin to moderate and control the
more primitive and reactive lower portions of the
brain.
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Sequential Development
All theoretical frameworks in developmental psychology describe this sequential development
of ego-functions and super-ego. Simply stated, inhibitory capabilities gradually develop so as
to modulate the more primitive, less mature, reactive impulses of the human brain.
Loss of cortical function through any variety of pathological processes (e.g., stroke, dementia)
results in regression. Further, any deprivation of optimal developmental experience that leads
to the underdevelopment of cortical, sub-cortical, and limbic areas will result in persistence of
primitive, immature behavioral reactivity and predisposition to aggressive behavior.
Coming Up
So, what do you make of all this? How is the information coming together in your brain? How
do you think this new knowledge will help you in your work with children? Please visit the
Message Board and share your thoughts.
In our next (and last) lesson, we'll go over some of the many resources available for learning
more about children and the incredible brains we all possess. We'll tie up the course with a
few brainy factoids, and you and your brain will be on your way.
Remember!
Remember that the brain is not just one large mass of equivalent tissue. It has a hierarchical and
complex organization.
Life as a Constant Test
Children in a state of fear retrieve information from the world differently than children who feel calm.
We all are familiar with test anxiety. Imagine what life would be like if all experiences invoked a similar
and persistent feeling of anxiety. If a child has information stored in cortical areas, but is very fearful at
a specific moment, the information becomes inaccessible.
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Use it or Lose it
A key neurodevelopmental factor that plays a major role in determining the brain's moderating
capacity is its amazing ability to organize and change in a "use-dependent" fashion.
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Lesson 6: Resources
You've taken in a tremendous amount of information in the past few weeks. I wouldn't be
surprised if it all seems a little overwhelming. Our brains are so complex and so magnificent
in their function. It is my hope that this course will spark an interest in you to learn more.
There is an abundance of interesting, accessible reading material available regarding the brain
and related subjects. Here are a few of my top picks. I recommend that you check some of
them out.
·ð Magic Trees of the Mind: How to Nurture Your Child's Intelligence, Creativity and
Healthy Emotions from Birth Through Adolescence by Marian Diamond and Janet
Hopson
This book is a thoughtful review of much of the work on enriched environments and brain
development. Dr. Diamond is a pioneer in these studies. The most fascinating elements of this
book include the sections examining the work that has been done on enriched environments
for human children. Included are practical suggestions for parents and a very good resource
section. It targets the general population.
·ð The Scientist in the Crib: Minds, Brains and How Children Learn by Alison Gopnik,
Andrew N. Meltzoff, and Patricia Kuhl
This is a new book by a team of respected neuroscientists who have been studying the
development of language in babies. This group writes a very well-referenced and thoughtful
book about the value of early childhood experience in cognitive and emotional development.
There is actually little about brain structure, organization, or development, but it does provide
much about principles of brain functioning. This book is also appropriate for general
readership.
·ð Inside the Brain: Revolutionary Discoveries of How the Mind Works by Ronald
Kotulak
This is a book by a Pulitzer Prize winning science writer. He reviews some of the emerging
findings in the pre-clinical neurosciences with a focus on mental health, violence and
aggression, substance abuse, and other neuropsychiatric disorders. This is a very readable
book, and it's a good start for anyone interested in learning about the brain.
·ð The Scientific American Book of the Brain: Consciousness, I.Q. and Intelligence,
Perception, Disorders of the Mind, and Much More
This book, compiled by the editors of Scientific American magazine, examines just about
every aspect of brain functioning -- from behavior to intelligence to mental illness. It is an
excellent resource for anyone interested in how the brain works.
There are hundreds of places to learn more about the brain. A few useful starting places are
listed below.
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The Human Brain: Dissections of the Real Brain
You really want to see what the brain looks like? This site has a well-presented dissection of
the human brain. It is a useful way to see what these areas really look like. Visit this site and
admire the work of Terence H. Williams, M.D., Ph.D., D.Sc., Nedzad Gluhbegovic, M.D.,
Ph.D. and Jean Y. Jew, M.D.
Society for Neuroscience
The Society for Neuroscience is the world's largest organization of scientists and physicians
dedicated to understanding the brain, spinal cord, and peripheral nervous system. This site has
a number of very useful materials for professionals who don't have specific expertise in the
neurosciences. The educational programs and materials are well-written, clear, and accurate.
Overall, this is an excellent resource.
These resources will be periodically updated and posted in a special section of the
ChildTrauma Academy Web site. Visit www.childtrauma.org for updates and for other
resource materials about traumatic events and children.
Action potential: This is an electrical charge that travels down the axon of a neuron to the
synaptic terminal. Once there, it can increase or decrease the probability that hundreds of
intracellular vesicles filled with neurotransmitter will fuse with the pre-synaptic membrane of
that neuron, and release the neurotransmitter into the synaptic cleft. The action potential
occurs when the neuron has been activated and temporarily reverses the electric polarity of
the interior membrane from negative to positive.
Amygdala: This is a structure in the forebrain. It is part of the limbic system and plays a major
role in emotional memory and the response to threat.
Axon: This is the tiny fibrous extension of a neuron, which travels away from the cell body to
other target cells (neurons, muscles, glands).
Autonomic Nervous System: The ANS is that part of the nervous system responsible for
regulating the activity of the body's other organs (e.g., skin, muscle, circulatory, digestive,
endocrine).
Central Nervous System: This is the portion of the nervous system comprising the spinal cord
and brain.
Cerebellum: This is a large structure resembling a cauliflower on the top of the brainstem.
This structure is very important in motor movement and motor-vestibular memory and
learning.
Cerebral Cortex: This is the outermost layer of the cerebral hemispheres of the brain. The
cortex mediates all conscious activity including planning, problem solving, language, and
speech. It is also involved in perception and voluntary motor activity.
Cognition: This refers to the mental process by which we become aware of our environment,
and use that awareness to problem solve and make sense out of the world. It is somewhat
33
oversimplified, but cognition refers to thinking and all of the mental processes related to
thinking.
Glia: These are specialized cells that nourish, support, and complement the activity of
neurons in the brain. Actrocytes are the most common and appear to play a key role in
regulating the amount of neurotransmitter in the synapse by taking up excess
neurotransmitter. Oligodendrocytes are those glia that specialize to form the myelin sheath
around many axonal projections.
Hippocampus: This is a thin structure in the subcortex shaped like a seahorse. It is an
important part of the limbic system and plays a major role in learning, memory, and emotional
regulation.
Homeostasis: This is the tendency of a physiological system (i.e., a neuron, neural system, or
the body as a whole) to maintain its internal environment in a stable equilibrium
Hypothalamus: This is a group of important nuclei that mediates many important functions. It
is located at the base of the brain, and is connected to the pituitary by a network of specialized
blood vessels. The hypothalamic nuclei are involved in regulating many of the body's internal
organs via hormonal communication. The hypothalamus is a key part of the hypothalamic-
pituitary-adrenal (HPA) axis that is so important in the stress response.
Limbic System: This is a group of functionally and developmentally linked structures in the
brain (including the amygdala, cingulate cortex, hippocampus, septum, and basal ganglia).
The limbic system is involved in the regulation of emotion, memory, and in processing
complex socio-emotional communication.
Neuron: A cell specialized for receiving and transmitting information. While neurons have
tremendous heterogeniety in structure, they all have some form of both dendritic projections
(that receive incoming information) and axonal projections (that communicate to other cells).
Neurotransmitter: A chemical that is released from a neuron, and that relays information to
another cell by binding to a receptor on the membrane of the target cell.
Plasticity: This refers to the remarkable capacity of the brain to change its molecular,
microarchitectural, and functional organization in response to injury or experience.
Synapse: This is the specialized space between two neurons that is involved in information
transfer. Neurotransmitter is released from one neuron, enters the synaptic cleft (space), and
sends a signal to the post-synaptic neuron by occupying that receptor's receptors.
Thalamus: This is a paired structure of two tiny egg-shaped structures in the diencephalon.
The thalamus is a crucial area for integrating and organizing sensory information that comes
into the brain. In the thalamus, information is processed and forwarded to the key cortical
areas, where more processing and integrating take place.
Use-dependent: This refers to the specific changes in neurons and neural systems following
activation. Repetitive, patterned stimulation alters the organization and functioning of neurons
and neural systems and, thereby, the brain.
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·ð Remember that the brain is not one single system. It is many interacting and
interconnected systems organized in a specific hierarchy. The most complex areas
(i.e., cortex) are found at the top and the least complex (i.e., brainstem) at the bottom.
·ð Different parts of the brain -- different "systems" in the brain -- mediate different
functions. For example, the cortex mediates thinking, while the brainstem mediates
states of arousal.
·ð All systems in the brain are comprised of networks of nerve cells (neurons). These
neurons are continuously changing (in chemical and structural ways) in response to
signals from other parts of the brain, the body, or the environment (e.g., sight, sound,
taste, smell).
·ð These molecular, chemical changes in neurons allow for the storage of information.
The storage of information is the basis for all types of memory, whether they are
motor, sensory, cognitive, or affective.
·ð Each part of the brain mediates different, specific functions. Each part also stores
information (memory) that is specific to its function. This allows for different types of
memory. For example, cognitive memory consists of names and telephone numbers,
motor memory tells you how to ride a bicycle or type on your computer keyboard, and
affect memory prompts feelings of nostalgia.
·ð The brain stores information in a use-dependent fashion. The more a neurobiological
system is activated, the more that state (and the functions associated with that state)
will be "built in." For example, practicing the piano, memorizing a poem, or remaining
in a state of fear all exemplify different ways that the brain becomes activated through
use.
·ð Different states of arousal (e.g., calm, fear, sleep) activate specific neural systems.
Because the brain stores information in a use-dependent fashion, the information
stored (i.e., the memories) in any given situation depends upon the state of arousal
(i.e., the neural systems that are activated). One example of this is state-dependent
learning; another is the set of hyperarousal symptoms seen in Post-Traumatic Stress
Disorder.
A Complex System
The human brain, and its constituent parts, is the most complex system in the known universe.
Each of its one trillion separate cells is in a continuous process of changing in response to
chemical signals. From the moment of conception to the moment of death, the biology of each
individual human is constantly changing, and the greatest changes are those that take place in
the brain.
It is within this complexity that our species has found the capability to store the accumulated
experience of thousands of generations and create human culture. Our language, religions,
governments, childrearing practices, technologies, and economies are all man-made, yet all
depend upon the remarkable capacity of the brain to make internal representations of the
external world. It is this amazing plasticity and malleability of the human brain that allows
humanity.
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Getting Involved
Our society has been ineffective in preventing, identifying, and responding to the
maltreatment of children. The impotence of our social systems to help children does not mean
that you, as an individual, are powerless. Your actions can have dramatic impact on children
in your community and, by supporting the efforts of effective organizations, your actions can
impact thousands of children in this generation and in generations to follow.
There are many ways that you can choose to fight the maltreatment and trauma of children.
Whatever method you choose, know that however small your effort seems, your participation
is critical. In the end, unless we all participate in some fashion, we will always fall short of
our true potential as individuals and as a society. Choose to help in a way that works for you.
You may want to work directly with maltreated children, or you may choose to contribute in
any variety of important ways. Please remember, you don't need to work directly with the
child to be able to make a dramatic difference in their life.
Give Your Time
In your community, there are children that need the gift of attention, respect, instruction,
comfort, and hope. So many children from abusive settings have lost hope. Even brief
interactions with respectful, honest, and nurturing adults can be helpful to the abused or
traumatized child, allowing them to know that adults can be kind.
There are many ways to find children who need your time. Volunteer to be a foster parent, to
rock the crack-addicted infant in the hospital, to teach a child to read, to be an aide in the local
public school, to answer phones at a battered women's shelter. In all of these settings, you can
enrich the life of a child. You can give a child hope.
Give Your Skills
You may not realize how your skills can benefit maltreated children. Desperately underfunded
child protection, child welfare, and child mental health systems can always benefit from the
innovative use of your skills. A residential treatment center may need help with accounting or
computer programming. A local children's shelter may not have a library.
A dancer can teach some foster children how to dance. A computer programmer can teach
these children computer skills. A writer can write editorials/articles/books about these issues
or help an agency create a newsletter. Your skills, whatever they are, can be used to fight
abuse.
Give Your Money
In the United States, we spend more money on studying and treating abusers than we do on
their child victims. Research, clinical services, and specialized professional training in child
36
abuse are dramatically underfunded. You can help support these critical activities by
financially supporting effective and innovative programs such as the ChildTrauma Academy.
Please direct donations to:
The ChildTrauma Academy
5161 San Felipe, Suite 320
Houston, Texas 77056
Attn.: J. Rubenstein
Checks should be made payable to "The ChildTrauma Academy."
As you give time, skills, or money to help these broken children, you may find that your life
will be enriched and that hope has a new meaning for you. You can make a difference in the
life of a child with your time, and in the lives of many children with your financial support.
Choose to act.
Give Your Voice
Play a role in helping change the policies and practices that have allowed our society to ignore
children. Remember, children don't vote. And far too many traumatized children have no
effective adult advocacy. We allocate research and service-delivery dollars in the United
States in a way that reflects political power. Maltreated children have no political power in
this country, nor any other country.
Whenever you can, talk to the media. Talk with your local, state, and federal representatives
to inform them and urge them to think about the future of our children. Write letters or send e-
mails to make them aware of your concern. They all say that children are our future. Make
them walk the walk and not just talk the talk.
A Final Word From Your Instructor
I hope this course has provided an understanding of how the brain's very structure makes it so
able to be changed through an individual's life experience and environment. It is through such
knowledge that we, as parents, educators, mental health professionals, physicians, and others
can begin to truly understand the behaviors so often exhibited by children who have been
maltreated. Only through such an understanding can effective treatments and interventions be
given a viable chance.
I wish you the best of luck in your endeavors and thank you for your time and commitment to
issues of childhood maltreatment.
Bruce D. Perry, MD, Ph.D.
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