February 1, 2013 20:24
In order to understand how the brain perceives the external world, scientists need to acquire the ability to monitor the activity of neurons in real time during this same perception.
Japanese researchers have solved this problem by the example of the classical model organism — the zebrafish (Danio rerio). Because of its transparency of its embryos and larvae is the best suited to visualize neural activity in the brain. In addition, they are unpretentious and multiply rapidly.
To scientists for many years, there was a serious problem. The fact that the lens is a conventional optical microscope, and active and inactive neurons look about the same. Therefore, researchers have developed a number of indicators (substances that in special circumstances change color) and dyes. When it is in a certain type of nerve cell, they start to glow. That is, for example, when a neuron is activated, it is "filled" by calcium ions that bind with certain dyes, causing them to emit a glow of a color.
However, application of dyes has its drawbacks. And chief among them — the need to fix the animal, which severely limits the range of tasks.
To solve this problem, Junichi Nakai (Junichi Nakai) and his colleagues at Saitama University turned to the luminous genetic marker — green fluorescent protein (GFP)? and tied him with a substance that glows in the presence of large amounts of calcium ions. The researchers then introduced into the genome of zebrafish code that encodes the marker, tying it to a protein unique to the nerve cells.
As a result, activation of neurons, researchers have seen their bright glow without the use of dyes. The signal was so evident that there was no need to hold the fries in the study of their brain activity.
Well, what did they think of fish? As researchers found, first of all about the food. It is on the hunting behavior zebrafish genetic engineers and decided to try his creation. To this end, the larvae of fish hoisted celled organisms — paramecia (Paramecium).
Using a specially developed method of imaging, the researchers traced the relationship between the movement of paramecia, zebrafish behavior and activation of neurons in the relevant brain areas fish (midbrain). The latter, according to the scientists, the majority of the animals responsible for the coordination of eye movements and reactions to objects in their field of vision.
In an article published in the journal Current Biology, the researchers report that the activation of nerve cells larvae occurred in tandem with the movements of a single-celled: bright flashes of neural activity were observed at sharp movements paramecia. As a result, researchers in real time watching what happens to the brain substance, when the fish saw the production, "has planned" attack and grabbed the victim.
Zebrafish brain is very similar to the brain of mammals, including humans. This allows us to assume enormous importance of opening the Japanese genetic engineering to medicine. The researchers hope that their method over time will help to thoroughly understand and with the reactions of the human brain to various stimuli.