Role of Dopamine in Mood and Reward

In the nervous system, neurotransmitters play a crucial role in communication between neurons. One neurotransmitter, dopamine, is particularly significant in the brain's reward pathways and is involved in the regulation of mood, motivation, and pleasure. However, excessive dopamine activity is also associated with certain psychological disorders. Based on this information, which neurotransmitter is known to be primarily involved in the modulation of mood and reward functions within the nervous system?

Consider the properties and roles of various neurotransmitters when making your selection.