Neurotransmitter (Excitatory) - Setiawan

• Nerve cells, called neurons, are one of the building blocks of behaviour.
• The neurons send electrochemical messages to the brain so that people can respond to stimuli—either from the environment or from internal changes in the body. The process by which these messages are sent is called neurotransmission.
• The nature of information transmission in the nervous system is partly electrical and partly chemical.
• Every neuron has a certain threshold of excitation received from the other neurons, and if the sum excitation exceeds this threshold, the neuron "fires" -generates a brief pulse called action potential that travels along the axon to other neurons.
• When an action potential travels down the axon of the neuron, it releases neurotransmitters that are stored in the neuron’s terminal buttons.
• The neurotransmitters are then released into the gap between the neurons – called the synapse.
• After crossing the synapse, the neurotransmitters fit into receptor sites.
• Neurotransmitters are the body’s natural chemical messengers that transmit information from one neuron to another.

One type of neurotransmitter is Excitatory neurotransmitters. Excitatory neurotransmitters allow the impulse to cross the synapse. They produce stimulating effects on the brain. One type of excitatory neurotransmitter is dopamine. Dopamine is an excitatory neurotransmitter that is involved in motivation, controlling the brain's reward and pleasure centres and in regulating emotional responses.

One study that supports this is the Setiawan study. The aim of the Setiawan et al (2013) was to investigate whether one's level of sensitivity to alcohol and personality traits are related to dopamine responses in the brains of young, healthy social drinkers.

The procedure is as follows. Researchers studied 26 healthy young social drinkers from the city of Montreal and the university community at McGill. The sample ranged from 18 - 30 years old.  The sample consisted of 8 women and 18 men. To participate, they had to be free of any diagnosis of mental illness or drug dependence other than nicotine or caffeine. None of the participants was identified as having AUD, but 11 of the participants reported having a family member with AUD.

Participants were asked to first fill in a series of questionnaires - including a lifetime drug and alcohol use questionnaire and the Tridimensional Personality Questionnaire.  The researcher categorised the drinkers as either high or low risk for alcoholism based on personality traits and having a lower intoxication response to alcohol - that is, they did not feel as drunk despite having drunk the same amount as other drinkers.

Each participant underwent two PET scans on separate days.  The conditions were counterbalanced. Before the scan, a urine drug test and a Breathalyzer test were used to confirm that the participants were drug-free. They were also asked to abstain from nicotine and caffeine on the day of each scan.

Participants were told that they may or may not receive alcohol on either day. 30 minutes before the scan, they were asked to drink a mixture of orange juice and lemon-lime soda - or the same volume of the same drink, but including alcohol. Blood samples were taken before the drink, and then at 30, 60, and 90 minutes thereafter to measure blood alcohol levels.

The results showed that when drinking alcohol, those who were considered "high risk" for alcoholism showed significantly greater activity in the mesolimbic reward pathway - that is, greater dopamine levels in response to alcohol consumption. It should be noted that there was no significant difference in the two groups' lifetime exposure to alcohol, suggesting that the result is not simply because of one's history of alcohol consumption.  Members of the low-risk group, on the other hand, showed a decreased dopamine response.

In conclusion, these results align with the established understanding of dopamine as an excitatory neurotransmitter involved in motivation, reward processing, and emotional regulation. The heightened dopamine response observed in individuals at high risk for alcoholism suggests an increased sensitivity to the rewarding properties of alcohol(with dopamine transmitter), potentially contributing to the development and maintenance of problematic drinking behaviours.