「1-1-8 Brain research in the 20th century/Gene manipulation and behavioral neuroscience」の版間の差分

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With the completion of genome analysis, genes associated with a particular trait and their locations have been revealed, which enables us to regulate the expression of a specific gene.
In the middle of the 18th century, a clue to discovering the true function of the "nerve fibers" that run throughout the body, which were discovered through dissection, was uncovered.
Gene knockout techniques alter a specific gene in the stem cell stage, so that that gene is not expressed.


The Gene Knockout Method, used to understand the role of a particular gene product in brain function, was attempted relatively early, and has contributed to some important discoveries. (Fig.8)
This discovery was made by an Italian physician, physicist and philosopher, Luigi Galvani  in his "Discoveries in Bioelectricity"
(Luigi Galvani：1737－1798).


[[ファイル:1-08.jpg]]
In his experiments with the skinned leg of a frog, he fastened a copper hook into the frog's leg and hung it on a zinc galvanized iron railing.
Then he noticed that the frogs' legs twitched when the wind blew and the frog's leg came in contact with the railing.  (Fig.1)


The role of behavioral neuroscience is to clarify the influence of a genetic defect, by analyzing the
[[ファイル:p1-01.jpg]]
change in behavior of knockout mice under various conditions.


However, in knockout experiments, the mortality rate of fetuses is high, and even in thriving specimens, the phenotypical change can not always be seen due to alternative gene expressions occuring.
He investigated the cause and clarified that it was due to the electricity which flowed between the copper hook and the zinc galvanized iron railing (caused by the difference in ionization tendencies between copper and zinc.)
This discovery led shortly to the invention of an early electrical battery by Alessandro Volta and furthered electrical research.


To avoid these problems, Conditional Gene Targeting, a method by which the target gene in a mature specimen is isolated and expressed by substituting the sequences before and after the target gene, was designed and utilized.
Thus, Galvani realized that the "nerve fiber" was a cable to transmit electricity.Sensory information from the outside reaches the brain as an electrical signal, and the corresponding conditional reflex is transmitted from the brain to the muscles through the nerve fiber and causes movements.
Galvani confirmed that the conditional reflex was lost when the fascicle of nerve fibers reaching its legs was cut; therefore he theorized that the signals going to and leaving the brain were using the same nerve fiber.


{{QuizTitle}}


{{QuizTitle}}
<GIFT>
<GIFT>
The method to knockout the target gene in the stage of stem cell is considered ({widely effective ~= effective in a limited range ~quite limited, ~almost invalid}) in the brain science field.  
The person who discovered that the nerve fiber is a cable to transmit electricity was ({=Galvani~Volta~Ampere}).


To improve this method,({delayed knock out method  ~time limited knock out method  ~=conditional targeting method  ~slow targeting method}) that separates the target gene after birth was designed and  effectiveness has increased.
This discovery led to the realization that electricity flowed between two metals ({silver and zinc~Iron and copper~=zinc and copper}) due to differences in ionization tendencies.　　
</GIFT>
</GIFT>

2015年7月10日 (金) 16:31時点における版

In the middle of the 18th century, a clue to discovering the true function of the "nerve fibers" that run throughout the body, which were discovered through dissection, was uncovered.

This discovery was made by an Italian physician, physicist and philosopher, Luigi Galvani in his "Discoveries in Bioelectricity" (Luigi Galvani：1737－1798).

In his experiments with the skinned leg of a frog, he fastened a copper hook into the frog's leg and hung it on a zinc galvanized iron railing. Then he noticed that the frogs' legs twitched when the wind blew and the frog's leg came in contact with the railing. (Fig.1)

ファイル:P1-01.jpg

He investigated the cause and clarified that it was due to the electricity which flowed between the copper hook and the zinc galvanized iron railing (caused by the difference in ionization tendencies between copper and zinc.) This discovery led shortly to the invention of an early electrical battery by Alessandro Volta and furthered electrical research.

Thus, Galvani realized that the "nerve fiber" was a cable to transmit electricity.Sensory information from the outside reaches the brain as an electrical signal, and the corresponding conditional reflex is transmitted from the brain to the muscles through the nerve fiber and causes movements. Galvani confirmed that the conditional reflex was lost when the fascicle of nerve fibers reaching its legs was cut; therefore he theorized that the signals going to and leaving the brain were using the same nerve fiber.

Challenge Quiz

1.

The person who discovered that the nerve fiber is a cable to transmit electricity was ( Galvani Volta Ampere ).

2.

This discovery led to the realization that electricity flowed between two metals ( silver and zinc Iron and copper zinc and copper ) due to differences in ionization tendencies.

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