There are billions – perhaps trillions – of nerve cells in the brain. Some scientists theorize there are so many nerve cells because in the event of their death or alteration, these cells are not regenerated and therefore we require a surplus of them. And because their functions are so critical, nerve cells are found in abundance in every area of the brain.
Nerve cells – also called neurons – have many different functions, but overall these functions are primarily communication-related. Neurons communicate by sending and receiving signals to other neurons and nerve circuits, to glands and other hormone-related organs, to muscle cells and other parts of the central nervous system.
Neurons are arranged in circuits, though individual nerve cells do not physically touch. Instead, they float freely within the circuit.
A neuron has 4 primary components;
1. Cell Body: the actual body of the nerve cell
2. Dendrites: dendrites branch out from the top of the nerve cell body
3. Axon: the axon is a long “cord” that extends from the bottom of the cell body
4. Terminals: the terminals branch out from the end of the axonWhat Happens During Drug Use
When drugs enter the bloodstream, a signal is sent that excites certain dendrites in a nerve circuit. This signal is processed by the cell body, which in turn then sends instructions about the signal down through the axon. The axon conveys the signal and a neurotransmitter – often dopamine – is released by the terminals.
The neurotransmitter settles into the small gap between individual neurons – called the synaptic gap – and binds with receptors found in the dendrites of connected nerve cells. This causes the user to feel a euphoric sensation or “high.” When drugs like cocaine, heroin or meth interfere with this process, the neurotransmitter is not reabsorbed correctly by the terminals, resulting in neurotransmitter saturation. This causes the high to last for an extended period of time, whereas a natural release of a transmitter like dopamine normally causes a mildly pleasant feeling that quickly dissipates.How the Brain Corrects the Imbalance
Because drug use is essentially a chemical invasion of the brain, the central nervous system will seek to control the effects of the substance. This is accomplished through a process called drug tolerance, whereby users find it increasingly more difficult to get high.
Tolerance develops when changes are made to the way receptors bind with neurotransmitters, or when other processes in the nerve circuit are altered in order to reduce or eliminate the effects of the foreign substance. Unfortunately, this often means that the drug user will simply increase the dosage of drugs in order to overcome this growing tolerance. This is the beginning of the cycle of addiction.Permanency of Changes
Changes made to receptors and nerve cells are not reversible. This means that the brain of a drug addict will have significantly changed by the time they stop using. Because these changes are largely permanent, they may cause the addict to feel differently than they did before they began using. Adjusting to these changes is the most difficult part of long term recovery from addiction or alcoholism.
The evidence shows that addiction is not an issue of morals or character; it has its roots literally in our brains and therefore deserves to be treated as the serious health concern that it is. This is why addiction can happen to anyone: we are all wired the same. The sooner we can understand this, the sooner we can begin to offer addicts the right treatment solutions, beginning with a grounded public perception of the neurological nature of addiction.