Final Thoughts on Vitamin B12 Injections. 1  Vitamin B12 injections (or shots) are used to overcome vitamin B12 deficiency, which is common especially among the elderly, those with intestinal damage or disorders, people with pernicious anemia, and vegetarians/vegans.
Neurons communicate over long distances by sending signals called nerve impulses through the axons which make up a tract or nerve. Because each axon may branch into a whole tree, and because nerve impulses go down each branch when an axon divides, a single neuron may send signals to thousands of other neurons.
Synapses are tiny gaps between neurons, where messages move from one neuron to another as chemical or electrical signals. The brain begins as a small group of cells in the outer layer of a developing embryo. As the cells grow and differentiate, neurons travel from a central birthplace to their final destination. Chemical signals from other cells guide neurons in forming various brain structures. Neighboring neurons make connections with each other and with distant nerve cells (via axons) to form brain circuits. These circuits control specific body functions such as sleep and speech.