The Seeking System — This seems an important system to us because it appears to drive all behavior. ALL behavior. It also appears that self-harming behaviors, like addictions, are due to genetially/inherited impaired and broken brain seeking systems.
Seeking System — A major part of the Seeking system runs from a part of the midbrain via a bundle of in the middle of the brain (the medial forebrain bundle) to the lateral hypothalamus, and from there up to the ventral striatum, a major part of the so-called reptilian brain. The striatum is composed of many parallel tracts (giving it a striated appearance), and it is buried deep in the cerebral hemispheres and densely connected to the frontal lobes.
Neuroscientists today believe that the system underlies wanting or craving rather than actual pleasure. The Seeking system is held together not just by wiring but by chemistry.
Its neurons signal to each other with a neurotransmitter called dopamine. Drugs that make dopamine more plentiful, like cocaine and amphetamines, jazz the animal up, while drugs that decrease it, like antipsychotic medications, leave the animal apathetic. (The ventral striatum also contains circuits that respond to a different family of transmitters, the endorphins or endogenous opiates.
These circuits are more closely related to enjoying a reward once it arrives than to craving it in anticipation.
The Seeking system identifies goals for the animal to pursue, like access to a lever that it may press to receive food. In more natural settings, the Seeking system motivates a carnivorous animal to hunt. The animal stalks its quarry in what we can imagine is a state of pleasant anticipation.
Pinker, Steven (2011-10-04). The Better Angels of Our Nature: Why Violence Has Declined (Kindle Locations 11014-11022). Penguin Group. Kindle Edition.