Welcome to 2 minute neuroscience, where I simplistically explain neuroscience topics
in 2 minutes or less.
In this installment I will discuss the nucleus accumbens.
The nucleus accumbens is found in a part of the brain called the basal forebrain, which
is located near the front and bottom of the brain.
The nucleus accumbens is the major component of the ventral striatum, and is situated between
the caudate and putamen.
The nucleus accumbens is typically divided into two anatomical components: an outer shell
and a central core.
There are thought to be functional differences between these two regions, where the shell
is more associated with the limbic system and the core is more strongly connected to
the motor system.
It should be noted, however, that while this distinction between shell and core is clearly
seen in rodents, it is less evident in humans.
Although the nucleus accumbens is best known as part of the reward system, its functions
are much more complex than simple reward processing and are still not fully understood.
The nucleus earned its reputation as a key part of the reward system in a large part
due to its connections with the ventral tegmental area, or VTA.
Dopamine neurons project from the VTA to the nucleus accumbens as part of the mesolimbic
dopamine pathway and this pathway is activated in association with rewards.
However, the exact role of the nucleus accumbens in processing rewards is not completely clear.
It is thought that the nucleus accumbens likely plays a role in learning about rewards and
the stimuli that are associated with them.
It also seems to be important to stimulating the pursuit of rewards and the selection of
actions that are most likely to result in the attainment of a reward, along with the
suppression of actions that are less likely to be useful.
The nucleus accumbens also appears to be important in processing aversive experiences, however,
and in learning to move away from aversive stimuli.
Thus, the nucleus accumbens appears to be involved in responses to all motivationally-relevant
stimuli, whether rewarding or aversive.