The truth about the nerve cells that are “not restored”
How often do you hear the phrase: nerve cells are not restored. It is with these words that people are trying to convince not to worry. And until recently, this phrase was considered true. But some discoveries have allowed scholars to doubt the accepted dogma. So, do nerve cells (the process of medicine is called neurogenesis) recover in the human body?
Neurogenesis – a breakthrough in neurobiology
For a long time, neuroscientists were convinced that nerve cells were not able to recover. The author of this theory is considered to be the Spanish doctor, the founder of neuroscience, Santiago Ramon y Cajal. He argued that all the neural pathways are unchanged and fixed. Nerve cells die and are unable to recover.
This theory was based on the following principles:
Clinical. Patients diagnosed with neurological diseases associated with lesions of the central nervous system, are not restored. Alzheimer’s or Parkinson’s have a progressive deterioration. Treatment can get rid of unpleasant symptoms, but can not stop the disease.
Functional. The central nervous system is responsible for many complex mechanisms (the appearance of emotions, the manifestation of reflexes, the performance of movements). Neuroscientists believe that such functions require “the finest tuning”. Therefore, the appearance of new cells could disrupt the entire work of the CNS.
Learning theory. According to scientists, in the process of learning a person has formed neural networks. If you need to remember something, information is simply extracted from the desired grid. The emergence of new nerve cells in this theory is completely incompatible with memory.
Scientists have conducted research in the field of neurogenesis
However, even such an “infallible” theory has been refuted. Some experiments and discoveries questioned the dogmas of the Spaniard-neurobiologist. And before scientists again the question arose: whether human nerve cells are restored in humans or not?
Formation of neurogenesis
The concept of neurogenesis has been forming for several decades:
1962 Joseph Altman and a group of scientists discovered radioactive thymidine in the cells of the dentate gyrus. Such a substance is able to be inserted into the DNA of only those cells that can divide. Therefore, the detection of thymidine in the hippocampus (brain region) has confused many. However, it was not possible for scientists to prove that neurons were labeled.
1977 Researcher James Hinds and his colleague Michael Kaplan echoed the Altman experience. Through the use of electron microscopy, they were able to confirm that it was neurons that were labeled.
1989 Fernando Noteboom found in the brain of canaries, singing new songs, the formation of neurons.
2011. Evidence of neurogenesis was obtained in certain parts of the brain in mammals and humans.
What is neurogenesis
The nerve cell (called the neuron) is a rather complex structure. It possesses several branched processes (dendrites and axons). Due to these processes, neurons are in contact with each other or with other tissues (for example, with muscle fibers). If these connections are broken, then pathologies of the nervous system begin to develop in humans.
Nerve cells are not able to divide. Experimental attempts to cause division of neurons led to cell death. After all, in order to divide, the neuron had to lose all communication. Therefore, it was widely believed that neuronal cells were not restored.
Silent furnishing affects nerve repair
However, in the brain, the process of the emergence of new neurons. They are formed from progenitor cells. This process is called neurogenesis. The appearance of new neurons is found in the hippocampus and the subventricular zone. Nerve cells appear daily. Then the neurons move to other parts of the brain in which they carry out the functions assigned to them.
Factors affecting neurogenesis
To this day, the process of neurogenesis remains poorly understood and contains many mysteries. However, scientists managed to determine some patterns.
The appearance of new neurons in the brain is greatly enhanced by the following factors:
actions of some hormones (for example, estrogen).
Some things can slow neurogenesis. Such factors can aggravate the process of neuron formation:
use of glucocorticoids;
effects on the body of stress hormones (cortisol);
Given these features, the motto “Do not be nervous, because the nerve cells do not regenerate” is also relevant.
Pathologies that reduce neurogenesis
Some diseases can destroy neurons. Such pathologies can significantly slow down and sometimes completely stop the process of neurogenesis.
Due to constant depression
These diseases include:
Stroke. This is a pathology in which an acute impairment of blood flow occurs in the brain. There is a breakdown of connections of some neurons. Separate parts of the brain die.