The nucleus acumbens is a region located in the basal forebrain to the rear of the preoptic area of the hypothalamus. It, and the olfactory tubercle, together form the ventral striatum which is a part of the basal ganglia.
The cerebral hemispheres on each side of the brain have their own nucleus acumbens. These structures play a significant role in the cognitive processing of aversion, motivation, reward, incentive salience, pleasure, and positive reinforcement. The nucleus acumbens are also involved in the processing of fear, impulsivity, and placebo effects.