Dorsal striatum in the context of "Putamen"

The basal ganglia (BG) or basal nuclei are a group of subcortical nuclei found in the brains of vertebrates. Positioned at the base of the forebrain and the top of the midbrain, they have strong connections with the cerebral cortex, thalamus, brainstem and other brain areas. The basal ganglia are associated with a variety of functions, including regulating voluntary motor movements, procedural learning, habit formation, conditional learning, eye movements, cognition, and emotion.

The main functional components of the basal ganglia include the striatum, consisting of both the dorsal striatum (caudate nucleus and putamen) and the ventral striatum (nucleus accumbens and olfactory tubercle), the globus pallidus, the ventral pallidum, the substantia nigra, and the subthalamic nucleus. Each of these components has complex internal anatomical and neurochemical structures. The largest component, the striatum (dorsal and ventral), receives input from various brain areas but only sends output to other components of the basal ganglia. The globus pallidus receives input from the striatum and sends inhibitory output to a number of motor-related areas. The substantia nigra is the source of the striatal input of the neurotransmitter dopamine, which plays an important role in basal ganglia function. The subthalamic nucleus mainly receives input from the striatum and cerebral cortex and projects to the globus pallidus.

The nucleus accumbens (NAc or NAcc; also known as the accumbens nucleus, or formerly as the nucleus accumbens septi, Latin for 'nucleus adjacent to the septum') is a region in the basal forebrain rostral to the preoptic area of the hypothalamus. The nucleus accumbens and the olfactory tubercle collectively form the ventral striatum. The ventral striatum and dorsal striatum collectively form the striatum, which is the main component of the basal ganglia. The dopaminergic neurons of the mesolimbic pathway project onto the GABAergic medium spiny neurons of the nucleus accumbens and olfactory tubercle. Each cerebral hemisphere has its own nucleus accumbens, which can be divided into two structures: the nucleus accumbens core and the nucleus accumbens shell. These substructures have different morphology and functions.

Different NAcc subregions (core vs shell) and neuron subpopulations within each region (D1-type vs D2-type medium spiny neurons) are responsible for different cognitive functions. As a whole, the nucleus accumbens has a significant role in the cognitive processing of motivation, aversion, reward (i.e., incentive salience, pleasure, and positive reinforcement), and reinforcement learning (e.g., Pavlovian-instrumental transfer); hence, it has a significant role in addiction. In addition, part of the nucleus accumbens core is centrally involved in the induction of slow-wave sleep. The nucleus accumbens plays a lesser role in processing fear (a form of aversion), impulsivity, and the placebo effect. It is involved in the encoding of new motor programs as well.

The internal capsule is a paired white matter structure, as a two-way tract, carrying ascending and descending fibers, to and from the cerebral cortex. The internal capsule is situated in the inferomedial part of each cerebral hemisphere of the brain. It carries information past the subcortical basal ganglia. As it courses it separates the caudate nucleus and the thalamus from the putamen and the globus pallidus. It also separates the caudate nucleus and the putamen in the dorsal striatum, a brain region involved in motor and reward pathways.

The internal capsule is V-shaped in transection forming an anterior and posterior limb, with the angle between them called the genu.