Why dread a bump on the head?June 2012
Lesson 5: What happens to neurons after TBI?
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.
Guppy (Poecillia reticulata)
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, mousemodels are often used to investigate questions concerning genetics.
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