The Reward Circuit: How the Brain Responds to Natural Rewards and Drugs
By Micah Moen
[Female announcer speaking] Deep within the brain is a set of structures
called the limbic system. The limbic system contains the brain’s reward circuit or pathway.
The reward circuit links together a number of brain structures that control and regulate
our ability to feel pleasure. Feeling pleasure motivates us to repeat behaviors.
When the reward circuit is activated, each individual cell in the circuit relays electrical
and chemical signals. The small gap between the sending and receiving
cells is called the synapse. In the reward circuit, dopamine neurons release
the neurotransmitter dopamine. The released dopamine molecules travel across the synapse
and link up with proteins called dopamine receptors on the surface of the receiving
cell. When dopamine binds to the exterior of the
dopamine receptor this causes proteins attached to the interior part of the receptors to carry
the signal onward within the cell. Some dopamine molecules re-enter the sending
cell via dopamine transporters and can be re-released.
When a reward is encountered the pre-synaptic cell releases a larger amount of dopamine
in a sudden burst, Dopamine transporters will then quickly remove
the excess. Dopamine surges in response to natural rewards
help the brain learn and adapt to a complex world. However, drugs are able to hijack this
process contributing to unhealthy behaviors and consequences.