The dopamine drive: Mesolimbic reward pathway

Zani Zartashah¹, Aastha Relan², Ryan Ziae^3
1Honours Life Sciences, Class of 2022, McMaster University, zartashz@mcmaster.ca
²Honours Health Sciences, Class of 2023, McMaster University, relana@mcmaster.ca
³Honours Life Sciences, Class of 2022, McMaster University, ziaer@mcmaster.ca

DESCRIPTION

Dopamine is a chemical messenger that influences brain pathways that promote motivation and reward-driven behaviour.¹ Any object, event or activity can act as a reward if it causes one to learn or feel content.² The brain’s reward system, or mesolimbic pathway, is the circuitry that modulates dopamine release to translate the value of the reward into actions accordingly.³ First, dopamine-releasing neurons in the ventral tegmental area (A) are activated when one expects to receive a reward.³ These signals are sent to the nucleus accumbens (B), the interface for motivation and action.² Reward-related memories are enhanced by strengthening synaptic connections between neurons in the hippocampus (C), which is the brain’s learning and memory centre.² Emotional associations are also made when dopamine signaling occurs in decision-making centers such as the amygdala (D) and prefrontal cortex (E).² It is not the reward itself but the anticipation of the reward that powerfully induces such emotional reactions and memories.2 The more the anticipation there is, the more dopamine signaling occurs, resulting in a stronger drive to perform a behaviour.² For example, the caffeine within coffee acts as a reward that increases the availability of dopamine receptors in the brain, and consequently, dopamine signalling.⁴ Regular consumption of coffee and associated dopamine release can promote habit-building behaviour.⁵ Consuming more coffee increases dopamine signaling, further reinforcing anticipation for the reward.⁵ Caffeine-induced dopamine activity can create dependence on coffee, a demonstration of the reward system’s effect on behaviour.⁶

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