Ventral Tegmental Area (VTA) is the area that synthesizes dopamine, which then sends to nucleus accumbens. Nucelus accumbens is the pleasure center, and it is stimulated by the neurotransmitter dopamine from VTA. VTA also sends dopamine to prefrontal cortex which regulates and controls these impulses. The locus coeruleus is the area packed with norepinephrine; and when stimulated by a lack of the addictive substance, will drives the person to do anything necessary to obtain a fix.
The ventral tegmental area (VTA), a group of neurons at the very centre of the brain, plays an especially important role in this circuit. The VTA receives information from several other regions that tell it how well various fundamental needs, and more specifically human needs, are being satisfied.
Ketamine blocks glutamate NMDA receptors in the brain. Increases brain-derived neurotrophic factor (BDNF, important for long-term memory and the creation of new synapses) and restores healthy mushroom-shaped spines on the dendrites of neurons in the prefrontal cortex. It may also affect the monoamines norepinephrine (NE) and dopamine. In rats, increased the firing rate of NE neurons in the locus coeruleus and also increased spontaneous firing dopamine cells in the ventral tegmental area.