In which part of the nervous system is the accumulation of nerve cells located?

The nervous system consists entirely of nerve cells. The cells form clusters throughout the body. But the largest congestion is the brain. This system helps to control our livelihoods. We can respond to external stimuli thanks to her. We have conditioned reflexes from birth. There is a myth that nerve cells do not regenerate, but this is a misconception. Absolutely all cells in the human body recover and renew themselves rather quickly, it is just that the cells of this system are able to recover a little longer than others.