Neurophysiological Background Of Addiction
Introduction
Addiction is a disease taking many different forms. It is described as when a person is unable to stop a stimulus seeking behaviour despite experiencing negative consequences. In simple terms impulsive behaviour becomes compulsive behaviour. This may be in reference to using pharmacologically active substances or engaging in a specific behaviour, such as gambling or exercising compulsively. When a person is addicted, the brain’s reward system starts to operate in a different way, making it dependent on the substance that the person is addicted to. After a period refraining from ingesting such a substance, a person may start to experience symptoms and demonstrating signs of withdrawal. Such abstinences, while unpleasant, are mostly not life threatening. However, in severe cases complications of withdrawal such as epileptic seizures or cardiac arrhythmias can lead to death (Camí and Farré, 2003).
The Brain And How It Communicates
The brain contains between 100 million and 100 billion neurons depending on the species. The different parts communicate through neurons by small chemicals known as neurotransmitters. They are released from one neuron to the other through small gaps, known as synapses. These chemicals will then bind on the neighbouring neuron to convey the information further. All communication is dependent on the electrical charge of action potentials.
There are over 200 different neurotransmitters, and they can be categorized into two groups. Excitatory neurotransmitters, like glutamate and acetylcholine, which means they increase the likelihood of firing the action potential, and inhibitory neurotransmitters, such as serotonin and GABA, which decrease the likelihood. Dopamine is a neurotransmitter that acts both as an excitatory and inhibitory neurotransmitter and is connected with the reward system, making it an important player in addiction neurophysiology. To understand the reward system, we need to be familiar with certain structures of the brain and the tasks of the neurotransmitters.
Participating Structures Of The Central Nervous System
The Ventral Tegmental Area (VTA)
The Nucleus Accumbens (NAcc)
The Prefrontal Cortex
The Hippocampus
The Amygdala
The Functions Of Neurotransmitters
Dopamine
Glutamate
Gamma-Amino-Butyric-Acid (GABA)
Endorphins
The Reward System
Drugs Abusing The Reward System, By Influencing The Dopamine Pathway
Cocaine
Heroin
Cannabis
Treatment Of The Addicted Brain
Conclusion
References