Download Why dread a bump on the head? June 2012 Lesson 5: What

Why dread a bump on the head?
Lesson 5: What happens to neurons after TBI?
June 2012
Model Organisms Used in Neuroscience Research
Sea slug (Aplysia caligornica)
The neurons of this West Coast invertebrate are unusually
large—about 1 millimeter long at the most—and visible to the
naked eye. The sea slug’s cells are easily manipulated and useful
for understanding how we learn and how diseases like
Alzheimer’s work at the cellular level. Furthermore, the sea slug has only 20,000 brain cells, compared to
the 100 billion of a human brain. The neuroscientist Eric Kandel and his colleagues were awarded with a
Nobel Prize in 2000 for work using sea slugs to study how memories are formed at the molecular level.
Zebrafish (Danio rerio)
Zebrafish are great for studying a variety of human diseases. Besides their
easily observable and testable behaviors, these fish have a sleep cycle that
is very similar to mammals. Zebrafish are easier to take care of than mice,
and are used to study circadian rhythms and other research topics. For example, when scientists
injected stem cells from zebrafish into the diseased retinas of rats, the stem cells developed
characteristics of the rats’ neuronal cells. This is promising research for humans who suffer from
damaged retinal neurons, which is related to glaucoma and diabetes-related blindness.
Fruit fly (Drosophila melanogaster)
You may think nothing about this 3-mm long, tiny insect you see around
spoiled fruit or the trash, but this model organism has been used for over
100 years to study genetics. Fruit flies are convenient for this use because
they have only four chromosomes, including sex chromosomes X and Y.
However, these flies are so easy and cheap to breed, raise, and observe
that they have been used for many different types of studies including circadian rhythms, longevity, and
alcohol tolerance. Thomas Hunt Morgan is a famous scientist who received a Nobel Prize in 1933 for his
work using fruit flies to study the role of chromosomes in genetics.
Chimpanzees (Pan troglodytes)
This species is a member of the great ape family (Hominidae) along with
gorillas, humans, and orangutans. Their closeness in relation to humans
(we share 98% of our genome code) has made them useful for research
in language development, tool use, surgery, and infectious diseases such
as AIDS. Chimpanzees have even been launched into out space by the
United States space program NASA to study the effects of space travel on humans! In neuroscience,
chimps are used to study complex brain processes such as face recognition and reasoning skills.
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Why dread a bump on the head?
Lesson 5: What happens to neurons after TBI?
June 2012
Guppy (Poecillia reticulata)
Animal Testing
Non-human animals
have helped scientists
and doctors cure many
diseases and save
millions of human lives
by developing vaccines,
surgery and organ
transplant techniques,
and antibiotics. Today,
there are strict federal
policies regarding the
treatment of animals in
research in the United
States. Any scientist that
receives federal funding
must justify research
involving animals and
show that animals will
not be “unnecessarily
burdened.” This means
that the number of
animals used in research
is minimized,
experiments are refined
to reduce pain and
distress, and computer
or in vitro (intact or
natural state) models
are preferred in
experiments.
Guppies are used in genetic studies to
observe mating and behavior patterns.
The female guppy retains the embryos
inside her body, observable to the naked
eye, and gives live birth. It is known that females prefer complex and
unique color patterns in their male mates, and that this preference
contributes to color polymorphism, or multiple phenotypes, within the
guppy species. Current research is focusing on social and environmental
factors that affect a female’s selection of male mate and why females are
generally more attracted to novel males, those they have not seen before.
Planaria (Schmidtea mediterranea)
Planarians are invertebrate flatworms with
an amazing ability to regenerate. If you cut
a piece of the planarian that is 1/279th of
the body, an entire new flatworm can be
generated! Because they are also easily observable creatures, researchers
can manipulate planarians’ simple genome and observe changes in
response to stimuli and how their nervous system controls learning,
memory, and behavior. For these reasons, planarians can be used to
understand the human genes associated with stem cell development and
how these can be manipulated in neurogenesis and used to treat patients
with neurodegenerative disorders.
Rats (Rattus norvegicus) and Mice (Mus musculus)
Not all rodents are uninvited guests. In fact,
approximately 95% of non-human research
animals are rats or mice. They have a short life
span and can give birth to over 10 litters across
their lifetime! These qualities make rats and mice
great models for studying long-term effects
across generations. Neuroscientists use rodent
models to investigate the effects of brain
damage, neurological diseases, and novel
compounds on cognition. Scientists can study a number of cognitive
abilities such as learning, memory, fear, anxiety, depression, and drug
addiction. Rat models are superior to mouse models for researching
complex behavior, sophisticated surgical manipulations, or toxin
exposure. However, mouse models are often used to investigate
questions concerning genetics.
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