2-Minute Neuroscience: Reward System Video Lecture | A-Z Guide to Neuroscience - Personal Learning

Welcome to 2 minute neuroscience, where I
simplistically explain neuroscience topics
in 2 minutes or less.
In this installment I will discuss the reward
system.
The reward system refers to a group of structures
that are activated whenever we experience
something rewarding like using an addictive
drug.
When exposed to a rewarding stimulus, the
brain responds by increasing release of the
neurotransmitter dopamine.
Thus, structures that are considered part
of the reward system are found along the major
dopamine pathways in the brain.
The pathway most often associated with reward
is the mesolimbic dopamine pathway, which
starts in an area of the brainstem called
the ventral tegmental area, or VTA.
The VTA is one of the principal dopamine-producing
areas in the brain and the mesolimbic dopamine
pathway connects it with the nucleus accumbens,
a nucleus found in a part of the brain that
is strongly associated with motivation and
reward.
called the ventral striatum.
When we use an addictive drug or experience
something rewarding, dopamine neurons in the
VTA are activated.
These neurons project to the nucleus accumbens
via the mesolimbic dopamine pathway, and their
activation causes dopamine levels in the nucleus
accumbens to rise.
Another major dopamine pathway, the mesocortical
pathway, also originates in the VTA but travels
to the cerebral cortex, specifically to the
frontal lobes.
It is also activated during rewarding experiences
and is considered part of the reward system.
Because dopamine is released whenever we use
an addictive drug, researchers initially thought
dopamine must be the neurotransmitter that
causes pleasure.
More recent research, however, suggests that
dopamine activity doesn’t correlate exactly
with pleasure.
For example, dopamine neurons are activated
before a reward is actually received and thus
before the pleasure is experienced.
For this (and other) reasons, it is now thought
dopamine has roles other than causing pleasure,
such as assigning importance to environmental
stimuli associated with rewards and increasing
reward-seeking.
Whatever the precise role of dopamine in reward
is, the mesolimbic dopamine pathway is consistently
activated during rewarding experiences, leading
it to be considered the main structure of
the reward system.
Regardless, the actual network of brain structures
involved in mediating reward is much larger
and more complex than just this dopamine pathway,
involving many other brain regions and neurotransmitters.