The Function of Dopamine as a Neurotransmitter

Dopamine or 3,4-dihydroxyphenethylamine, is an organic chemical compound which plays an integral role in the human body and the brain. In the human body, dopamine is synthesized mainly in the kidneys and in the brain. Dopamine, as a chemical compound, works like a neurotransmitter. Neurotransmitters are chemicals which are released by the nerve cells or neurons. The neurotransmitters are transmitted from one nerve cell to another through a number of dopamine pathways. The brain consists of a number of these distinct dopamine pathways which would play a major role in determining the motivational components of reward motivated behavior (Schultz, 2013). For instance, conditioning theory of human behavior states that human beings are inherently inclined towards rewards and that they are motivated by it. The anticipation of a reward would increase the level of dopamine present in the brain. As a matter of fact, a number of drugs and chemical substances are often artificially (and usually illegally) injected into the human body to boost the levels of dopamine in the body. The following essay attempts to understand the impact of dopamine on human behavior.

The circuit of the brain which is instrumental in the neurological reinforcement of human behavior is known as the limbic reward system. This circuit is also known as the dopamine reward system. The use of any kind of substance, be it alcohol, drugs, marijuana, nicotine, cocaine and so on, has an impact on the limbic reward system (Ncbi.nlm.nih.gov, 2018). When an individual consumes such a substance, it triggers the release of dopamine, which as explained earlier, is a neurotransmitter. Increased levels of the dopamine neurotransmitter in the body would regulate and increase the sensations of pleasure in the body, especially that of satisfaction and euphoria (Simington, 2017). In fact, it has also been found that changes in the levels of dopamine in the body would lead to changes in reward reinforcement, cognition, motivation levels and motor or movement of the body (Lammel, Lim & Malenka, 2014). An increase of dopamine in the body would improve the mood of a person and cause a sense of euphoria. It would also make a person more agitated and restless, thus regulating body movement or motor activity of a person as well. However, excessive quantities of dopamine in the brain would result in aggressiveness, irritability, nervousness or even paranoia. The side effects in that case begin to resemble that of schizophrenia, since they may cause hallucinations or bizarre thoughts which are associated with dopamine usage (Howes, McCutcheon & Stone, 2015).

Normal day to day activities like consumption of coffee, eating, drinking or even sexual intercourse can result in activation of dopamine pathways, increasing the release of dopamine in the human brain. This results in immediate and temporary feelings of pleasure in the body. When the level of dopamine in the body subsides, the feeling of euphoria goes down as well. The process acts like a vicious cycle (Kim & Kyung, 2017). For instance, consumption of coffee, which has caffeine, works in the same way as the consumption of heroin, although the side effects are comparatively less. On consumption of coffee, the level of dopamine released in the body is increased. In this case, the neurotransmitter blocks the reception of adenosine which makes a person feel alert and active. That is why people tend to use coffee to stay awake or active. In other words, it boosts the system (Bayer, Lau & Glimcher, 2017). Caffeine also manipulates the dopamine production system in both animals and human beings so as to make them feel good. While usage of caffeine is good on a short term basis, it may lead to addiction in the long run. It is assumed that dopamine is what is responsible for the addiction. Caffeine and the excess release of dopamine in the body would affect human behavior in adverse manner in the long run, by altering sleep patterns. While a person may be able to sleep after consumption of coffee, he or she may still be sleep deprived and suffer from sleep disorders with regular consumption.

Dopamine and Reward-Motivated Behavior

Dopamine is also known as the molecule of happiness in the human body. When people consume substances like methamphetamine or cocaine, the dopamine pathways in the brain are altered which would mean that the neurotransmitter remains in the synaptic gap between neurons longer. Dopamine has a number of positive impacts on human behavior. Optimum levels of dopamine in the human body can drive a person towards his goals and provide him with the sense of pleasure when the goals are achieved (Farhud, Malmir & Khanahmadi, 2014). On the contrary, feelings of self doubt, lack of enthusiasm or procrastination are associated with low levels of dopamine in the body. Similarly, people who are more extraverted and outgoing have higher levels of dopamine in the brain which results in uninhibited personality types. On the contrary, a person who is meek, subdued and more introverted is likely to have lower dopamine levels in the body (Kim & Kyung, 2017).

Dopamine, in both humans and animals, has been labeled as the master molecule of addiction. This is because dopamine is considered to be the chief motivating factor behind repetitive actions. Since time immemorial, psychologists have suggested and studied how human behavior can be conditioned or how humans can be taught to act or behave in a certain way. Psychologists have also suggested that positive and negative reinforcements play a key role in regulating human behavior (Fiorillo, 2013). In the 1950s, scientists observed that when certain parts of animals’ brains were stimulated, it led to alterations in their behavior. This was observed in the case of humans as well. If drugs like amphetamine or cocaine were administered into human bodies, the sensitivity to feelings of pleasure increased. With repetitive administration, human beings are likely to choose the electric stimulation of these pleasure centers over normal day to day activities like eating. When an action which results in pleasure becomes repetitive in nature, it is known as positive reinforcement, which is associated with the neurotransmitter, dopamine (Ncbi.nlm.nih.gov, 2018).

In fact, it has also been found that dopamine is also linked with behavioral tendencies of avoidance – which are related to the feelings of fear and pain. Dopamine directly affects the part of the brain called nucleus accumbens, which plays a vital role in triggering the desire for something specific – food, sexual pleasure and so on – which finally pushes the person to act towards reaching the goal (Howe et al., 2013). In an experiment, scientists exposed animals to electric shocks, but also conditioned their behavior by teaching them to escape these shocks. The level of dopamine in their brains was remotely controlled. It was found that animals with higher dopamine levels were more effectively able to escape the shocks than animals with lower dopamine levels. In other words, dopamine in the human body would help people avoid situations that are potentially painful or unpleasant (Tye et al., 2013). This is one of the major impacts that dopamine has on human behavior. For instance, the consumption of cannabis or endocannabinoids fires the release of dopamine in the brain. Marijuana thus stimulates the release of the neurotransmitter, which can further help people avoid unpleasant situations (Volkow et al., 2014). This is particularly helps in the treatment of brain disorders like depression or post traumatic stress disorder. Since dopamine alters human behavior, it reduces the feelings of desolation and helplessness that such patients encounter. Instead, they are able to focus on feeling better and improving their situation (Chaudhury et al., 2013).

Dopamine and Addiction

In fact, the release of dopamine in the body is responsible for common human feelings and behaviors related to lust, love or attraction. The dopamine pathway in that case is known as the mesolimbic pathway. Attraction between two individuals involves the pathways of the brain which control and regulate reward behavior. This explains why the first few days and weeks of a new romantic relationship between two individuals can be exhilarating. Dopamine pushes people to do things that make them feel good – which in this case would involve meeting loved ones and sexual intercourse (Richard & Berridge, 2013). When there is attraction between two people, the level of dopamine released increases, along with the secretion of another hormone known as norepinephrine. This gives a person in love the feeling of being euphoric, energetic or even giddy. When one is exposed to someone he or she is attracted to, dopamine triggers the primary pleasure centers of the brain which include caudate nucleus. This results in human behaviors like blushing, shying away, refusal to acknowledge their feelings and so on. Similarly, unfavorable behaviors in love, which include erratic behaviors, irrationality or even jealousy, are also triggered by dopamine levels in the body. Since dopamine has almost complete dominance over the brain’s reward pathway, it controls both the bad and the good. In other words, dopamine is responsible for both the good and bad behaviors. Attraction and lust may be compared to any form of addiction, like cocaine. When someone consumes cocaine, dopamine signaling in the body is heightened which leads to an ephemeral high. It is similar in the case of relationships. In due course of time, people get “addicted” to their partners or become emotionally dependent on them (Robinson & Berridge, 2013). This explains the bitter feelings and cravings for companionship in case the relationship is terminated or in case of separation.

Dopamine has also been found to affect the human memory as well. The pre frontal cortex of the brain is in charge of human memory and higher ordered thinking. Secretion of dopamine can lead to improvements in a person’s memory. However it must be remembered that the levels of dopamine in the pre frontal cortex is extremely delicate. As a result, even the minute fluctuations in dopamine levels could alter a person’s ability to remember things. As a direct consequence, dopamine also affects the ability of an individual to learn or retain information acquired (Steinberg et al., 2013). If the levels of dopamine are high during a particular activity (it is released if a person is interested in the activity concerned), the person is likely to remember the event for a prolonged period of time and vice versa.

However, it has also been found that dopamine could potentially have adverse effects on human behavior with repeated stimulation. Dopamine is the neurotransmitter that is responsible for the human behaviors related to substance abuse and addiction (Volkow & Morales, 2015). Addiction may be a psychological phenomenon, but at the very core, it is a biological process which involves the repeated exposure to any biological substance. With repeated exposure, the substance alters the functioning of the brain’s neurons, which ultimately results in alterations in the dopamine pathways in the human brain. This process is responsible for addiction related behaviors like tolerance, cravings, dependence or sensitization (Nutt et al., 2015). Substance abuse or substance addiction refers to the habitual administration of a substance, which can have an impact on a person’s mood or states of consciousness. In other words, a person who is dependent on substance or addicted to it, will continue to crave for the substance even in its absence. Repeated or chronic use of substance would alter the reward circuitry in the body, which is a behavioral tendency known as counteradaption. Craving is one of the most crucial aspects of addiction, and is closely related with dopamine release. The pleasure and euphoria that is associated with dopamine secretion is responsible for the feelings of cravings in the absence of the substance which triggers dopamine release (Volkow et al., 2014). Craving is a human behavior which becomes closely associated with specific memories. In other words, use of stimulants could condition human behavior in such a manner that any stimuli (specific locations, paraphernalia, friends who use substances, moods et cetera) which have been previously paired with the substance would lead to an intense desire or arousal for the substance. In fact, dopamine or the reward circuitry of the brain can also be said to be responsible for the withdrawal symptoms and relapse which are common in patients recovering from substance addiction.

Dopamine and Personality Traits

In conclusion, it can thus be said that dopamine, a neurotransmitter which occurs naturally in the human body, is one of the most important factors which regulate human behavior. There are a number of aspects of human behavior, both positive and negative, which are regulated by the dopamine pathways present in the human brain. When a person consumes certain substances like cocaine or marijuana, the dopamine pathways in the brain are activated and higher levels of dopamine are released in the human body. This gives rise to feelings of euphoria and pleasure. In other words, dopamine as a neurotransmitter regulates the reward circuit in the brain, resulting in positive and negative reinforcement of behavior. However, as the discussion above shows, dopamine is not simply concerned with positive behavior. Certain negative aspects of human behavior like addiction and substance abuse are also associated with dopamine.

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