Video summary
The National Institute of Mental Health (NIMH) is dedicated to advancing research into mental illnesses such as schizophrenia, depression, anxiety, and panic disorders by first establishing a deep understanding of normal brain function. This foundational knowledge is essential for developing effective treatments and prevention strategies, though it presents a significant challenge because it requires deciphering complex neural pathways and molecular mechanisms that govern behaviors ranging from basic survival to high-level skills like winning at chess. Recent progress in this field has been driven by a growing community of scientists and unprecedented technological innovations that provide researchers with new windows into the brain's intricate workings.
At the heart of these discoveries is the cerebral cortex, the outermost layer of the brain which has evolved more extensively in humans than in any other species, making it the primary structure responsible for higher mental functions. Because the physical space within the skull limits the overall size of the brain, the cortex has developed extensive folds, ridges, and grooves to increase its surface area and tissue volume. This complex structure consists of two hemispheres connected by a massive bundle of nerve fibers that cross from side to side, creating a highly interconnected network where any single nerve cell can form thousands of connections with others. To visualize this complexity, specialized imaging allows scientists to observe individual cells deep within the cortex, revealing black-colored neurons with branching dendrites that receive signals and axons that transmit them across tiny gaps called synapses.
The communication between neurons occurs at these synapses through a rapid and precise chemical process involving synaptic vesicles, which act like miniature balloons filled with neurotransmitters. When an electrical impulse reaches the end of a nerve cell, proteins orchestrate the movement of these vesicles toward the membrane, causing them to fuse and release their chemical contents into the synaptic cleft. These molecules then diffuse across the tiny space to bind with receptors on the neighboring neuron, triggering an electrical response that completes the transmission of the message. This entire sequence happens in less than a thousandth of a second and occurs billions of times throughout the brain simultaneously, creating the complex interplay of chemical, electrical, and physical events that underlie all human experiences, from seeing sights and hearing sounds to forming ideas and initiating actions.
Even slight errors or variations in these neural events can lead to the abnormalities that characterize most brain disorders and mental illnesses, highlighting the delicate balance required for healthy cognitive function. By unraveling the intricacies of how neurons communicate and how these processes relate to behavior and cognition, scientists are moving closer to providing specific treatments, cures, and preventive measures for a wide range of conditions. Ultimately, this detailed understanding of the brain's machinery empowers researchers to fulfill their mission of ensuring the mental health of the nation by transforming basic biological knowledge into practical solutions for those who suffer from mental illness.
Read the full video transcript
The National Institute of Mental Health,
or NIMH, has the mission of supporting
research on mental illness, including
schizophrenia, depression, anxiety, and
panic disorders. The key to helping
those who suffer from mental illness is
to first understand normal brain
function.
This knowledge can then be applied to
help treat or prevent mental illness.
This is a challenge because it involves
understanding the neural pathways and
molecular mechanisms subserving
behaviors like winning at chess.
Now we are well on track toward
unlocking the mysteries of some of those
special abilities.
Progress in brain research has been due
both to the increasing number of
scientists interested in studying the
brain and to unprecedented technological
innovations.
These new tools give us a window to the
brain.
The cerebral cortex is the outermost
covering of the brain which has evolved
in humans further than in any other
species, and what is most responsible
for making humans human.
It is also the structure most associated
with higher mental functions. With its
multiple folds, ridges, and grooves, the
cortex is made up of two similar-looking
hemispheres joined at the middle by an
extensive bundle of nerve fibers which
cross from side to side.
One of the keys to understanding the
brain is to recognize that nerve cells
are highly interconnected. Any given
nerve cell may make thousands of
connections with other nerve cells. The
orange-looking surface in this image is
the cerebral cortex.
Since the size of the brain is limited
by the space within the skull, the only
way to increase the amount of cortical
tissue is to fold it.
With a specialized method, we can look
deep into the cortex and see individual
cells.
Here they appear black and have branches
coming from them. As magnification
increases, we see greater detail in the
network of the branches.
These are dendrites, which are the
appendages of neurons, which will
receive synaptic connections from other
cells.
Connections are made with another
specialized process called an axon. The
place where communication occurs between
an axon and a dendrite is called a
synapse.
Synapses are the communication links
between neurons. Remember, thousands can
occur along a single dendrite.
Understanding how neuronal communication
occurs at the synapse is one key to
understanding the most interesting
questions,
like how memories are stored and how
learning occurs.
Indeed, scientists now believe that
disruptions of normal activity occurring
at synapses are involved in several of
the disorders we call mental illness.
Our current understanding of how
synapses work is represented in this
computer animation.
As we dive deeper into the cell's own
structure, down into a single axon
terminal at a synapse,
we see small round objects, which are
the synaptic vesicles.
They're like tiny balloons, miniature
containers filled with chemical
neurotransmitters.
When an electrical impulse reaches the
nerve terminal, proteins in the watery
soup orchestrate the movement of these
vesicles toward the membrane, forming
one side of the synapse.
The visualization is slowed down here,
but in real time, this process happens
in less than a thousandth of a second.
As the transmitter-filled vesicles touch
the inside of the nerve terminal
membrane, their own membrane fuses with
it. When this happens, the inside of the
vesicle opens into the synaptic cleft,
and transmitter molecules diffuse across
this tiny space to reach their target
receptors on the other side.
This causes electrical conduction to
occur, completing the propagation of the
neuronal message across the cleft.
The processes of neural conduction and
neurotransmission occur by the billions
throughout the human brain.
It is this complex interplay of
chemical, electrical, and physical
events which underlies the rich tapestry
of everyday experiences, the sights we
see, the sounds we hear, the feelings we
experience, the activities we initiate,
and the ideas we ponder.
Even slight errors or variations in any
of these neural events can lead to the
kind of abnormalities which underlie
most of brain disorders, including
mental illness.
By understanding the intricacies of
neural activities and how they are
related to cognitive and behavioral
processes, we are on the threshold of
providing specific treatments and
ultimately cures and preventions in our
mission to ensure the mental health of
the nation.