What does the brain do?
The brain is responsible of controlling the five senses: vision, hearing, taste, smell and touch. It also
controls other basic functions such as: movement, breathing, heart rate, body temperature, speech,
pain and sleep. The brain is that much more unique and fascinating to us because it is where our
thoughts, memories and emotions are formed. The study of the brain and how it functions is known
as neuroscience.
What is our brain made of and how do we study it? The brain is made of many cells called neurons.
In fact, the average human has 100 billion neurons. When neuroscientists study neurons, they need
to open the brain and look inside it using techniques such as microscopy. This is only possible using
laboratory animals such as mice. The average mouse brain is smaller (4 million) and lighter (about
0.5 grams) than the average human brain (1500 grams) but we can still use it to study how the
human brain functions. This is because the structure, functions and genes of neurons are very similar
between the human and mouse.
In the brain, a structure called the hippocampus controls memory and learning processes in both
mice and humans. Diseases such as epilepsy, amnesia, and Alzheimer’s are caused by damaged or
dying neurons in the hippocampus. Neuroscientists are keen on studying the hippocampus because
it is one of the few structures in the adult brain in which new neurons are constantly produced. This
process is called ‘adult neurogenesis’ and we study it mainly by measuring how many neurons are
born and observing the structure of these neurons as they grow. To visualize the neurons and glial
cells, we apply markers that label the cells and allow them to be viewed under the microscope and
their images captured with computer software.
Neurons
Neurons are the building blocks of the brain that control its many functions. They are arranged so
that they are linked to each other and communicate as networks. Information in neurons is
communicated by:
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Electrical signals which are transmitted through their wire-like extensions called axons
Chemical messengers which they use they communicate with each other
The Astrocyte
Other types of cells known as glial cells also exist in the brain to help neurons carry out their
functions. These are the Astrocytes.
Astrocytes provide nutrients and help protect and repair neurons. The ‘astro’ in the name of these
cells refer to their star-like appearance.
The Oligodendrocytes
Oligodendrocytes allow neurons to transmit their electric signals quickly.
They do this by insulating the axons of neurons with a sheath of myelin- this is similar to the plastic
covering on a wire which ensures the electric signal is delivered efficiently.
By studying how neurons of the hippocampus survive and function, we can understand the memory
and learning processes of the brain.
Why are zebrafishes used to study the brain?
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Ease of breeding
Development studies easily done
Young are transparent with visible organs
Ease of genetic manipulation
Behavioral studies from observing swimming patterns
Though small, the zebrafish brain has similar structures as the human’s.
The Songbird
In canaries and zebra finches, three vocal control areas in the brain are strikingly larger in males than
in females. A fourth, area X of the lobus parofactorius, is well developed in males of both species,
less well developed in female canaries, and absent or not recognizable in female zebra finches.
These size differences correlate well with reference to auditory information, and females do not
normally sing. Exogenous testosterone induces singing in female canaries but not in female zebra
finches.
The songbird brain
A side view of the songbird brain, with the anterior to the right. Gray motor control nuclei are critical
for both learning and production of the song, while orange nuclei are mainly related to song
plasticity. The midbrain VTA provides dopaminergic input to orange nuclei.
Reflections
After visiting the science center during the brain awareness week to learn about the brain, I have
indeed gain a lot of valuable information. I have learnt many thing that are not taught in textbooks.
Some examples of what I had learnt are namely the brains of different types of animals: monkey,
mouse, songbird, zebrafish. I had a lot of fun viewing the brain specimens through microscopes in
the DNA lab. I saw parts of the monkey’s brain and found out that it looked almost like a human
brain. The surface area of the monkey’s brain was more than the mouse and other animal’s but
smaller than the human brain. This explains why the monkey is able to think quickly and almost as
smart as a human. Another interesting animal’s brain was the zebrafish. When I looked through the
microscope, I saw the young of the zebrafish. It was transparent except for its organs. I was amazed
when I saw it move. Another experiment that was conducted on fruit flies was interesting too. After
they added a certain gene in the brain of the fruit flies, they were not as active as before. Another
station I went to was on cognitive sleep test. I learnt things about the different stages when sleeping
example: light, deep, very deep sleep, etc. I also saw a video about a sleep test conducted. This trip
to the science center had amazed me by the powers of the brain. I had a memorable learning
experience there.
Photos