The striatum of the brain, also called the striate nucleus or striate body, is involved in a number of different cognitive processes. This portion of the brain is called the striatum because its structural organization is such that it appears to be striped with layers of gray and white matter. The striate nucleus is part of the cerebrum of the brain, which is also called the forebrain due to its frontal location.
The striatum comprises three separate structures: the caudate nucleus; the putamen; and the fundus, which links the caudate nucleus and putamen together. All of these structures are also part of the basal ganglia system, which plays a major role in learning, motor control, and several other cognitive processes. Large amounts of sensory input are received via the striate nucleus and channeled to other structures in the basal ganglia for processing.
There are several different types of neurons located within the striate nucleus. Most of this part of the brain is made up of medium spiny neurons, which are important in controlling body, limb, and eye movement. Around 1% of cells are spidery cholinergic interneurons, which respond to a neurotransmitter called acetylcholine, and are thought to play a role in determining behavioral responses.
Several different cognitive functions and processes are known to be associated with the striatum of the brain. The most well-defined role of this structure is in planning and executing pathways of movement. In addition, the striate nucleus is important in the reward pathway. This term describes the complex network of brain processes that regulate motivation, and the generation of rewarding feelings and sensations. The reward pathway provides the body or mind with a reward, such as pleasurable sensations or feelings, for executing behaviors which promote individual or species survival.
The importance of the striate nucleus is reflected not only in the types of functions it is associated with, but also in the types of diseases which affect this region of the brain. Two of the most devastating progressive brain disorders, Parkinson’s disease and Huntington’s disease, are associated with striatum dysfunction. In each case, disruption of the striate nucleus leads to disruption of the processes this part of the brain is involved in regulating.
One of the key aspects of Parkinson’s disease, for example, is that certain types of neurons in the basal ganglia system no longer respond to a neurotransmitter called dopamine. Because this part of the brain is important in controlling and executing movement, Parkinson’s disease is characterized by tremors, muscle rigidity, and other forms of dysfunctional movement. In Huntington’s disease, a mutant form of a protein called huntingtin accumulates in the striate nucleus, preventing normal function and leading to movement and behavior disorder.