Strange effects of nuclear tests

The testing of ground-based nuclear bombs in the 1950s and 1960s unknowingly gave scientists today a way to prove that the brains of adults still steadily produce nerve cells. new.

Researchers once believed that the human brain did not change much after it had completed its adult stage. This view is now considered outdated, as recent studies reveal the changing ability of adult brains.

Most of these flexible changes are related to the organization of the brain. Brain cells can change connections and communicate between them with other brain cells. However, the question is, does the human brain produce entirely new neurons in adulthood?

In adult mice, hippocampus - a structure deep in the brain, linked to memory and orientation, always transfers cells. Some biological signs associated with this transfer are also detected in the walrus region in the human brain. However, the first direct evidence of the formation of new brain cells in the hippocampus was obtained by a 1998 study of the brains of five people who received the BrdU compound.

A prickly neuron with branches helps communicate with other neurons.(Photo: Live Science)

The results of this study show that nerve cells in the hippocampus of volunteers collected BrdU into their DNA, implying that they formed after injecting compounds into the brain. The oldest in the 72-year-old study, which means that the production of new neurons continues in old age.

In an effort to find more evidence for the discovery, biologist Kirsty Spalding of the Karolinska Institute in Sweden and colleagues began a project to monitor the age of nerve cells in the human brain through a work unusual tool: molecules left over from the Cold War nuclear bomb tests.

From the mid-1945-1962 period, the US conducted hundreds of tests on ground bombs. These tests ended under the 1963 Limited Test Ban Treaty, but their effects remained in the atmosphere. The neutrons that fly out of the atomic bombs react with nitrogen in the air, creating a large amount of carbon 14, an isotope of carbon.

Like carbon in the air, carbon 14 also combines with oxygen to form carbon dioxide. Plants will absorb and use these carbon dioxide in photosynthesis. People eat those plants as well as some animals digest them, so the 14th carbon is finally present in their bodies.

When a cell divides, it uses carbon 14, bringing this carbon isotope into the DNA of the newly forming cells. Carbon 14 decays with time at a known rate, so scientists can determine exactly when new cells are produced through that decay.

Spalding's team discovered, 1998 evidence is correct: The hippocampus in the human brain always produces new neurons. In fact, one third of the brain region is responsible for transferring cells with about 700 new neurons born every day in each hippocampus (humans have two identical and symmetrical hippocampus zones in each side of the brain. Neurons in the hippocampus also die every day, causing a total amount to be slightly unbalanced by the decline in cells due to age.

The transfer takes place in the dentate gyrus backbone of the hippocampus, which contributes to new memories. The team still does not know the function of this continuous regeneration, but it may involve allowing the brain to cope with new situations.

Mrs. Spalding's team used the same techniques to examine other areas of the brain, including the cerebral cortex, cerebellum and nipple area, but found no evidence of newly emerging neurons. currently in these areas.