The globus pallidus is a structure in the brain which is involved in the regulation of voluntary movement. It is part of the basal ganglia, which, among many other things, regulate movements which occur on the subconscious level. If the globus pallidus is damaged, it can cause movement disorders, as its regulatory function will be impaired. There may be cases in which damage is deliberately induced, as in a procedure known as a pallidotomy, in which a lesion is created to reduce involuntary muscle tremors.
This area of the basal ganglia receives input from another area, called the striatum, which has two parts, the caudate nucleus and the putamen. This data is routed to the thalamus, either directly or indirectly. In the case of the interna, one area of the globus pallidus, the structure can feed directly to the thalamus. The externa, which lies, as one might imagine, on the outside of this structure, feeds information to the interna, where it can be passed on to the thalamus.
When it comes to regulation of movement, the globus pallidus has a primarily inhibitory action which balances the excitatory action of the cerebellum. These two systems are designed to work in harmony with each other to allow people to move smoothly, with even, controlled movements. Imbalances can result in tremors, jerks, and other movement problems, as seen in some people with progressive neurological disorders characterized by symptoms like tremors.
The basal ganglia act on a subconscious level, requiring no conscious effort to function. When someone makes a decision to engage in an activity such as petting a cat, for example, these structures help to regulate the movement to make it as smooth as possible, and to respond to sensory feedback. Likewise, the globus pallidus is involved in the constant subtle regulation of movement which allows people to walk, talk, and engage in a wide variety of other activities with a minimal level of disruption.
The globus pallidus is classified as a subcortical structure, lying deep inside the brain. It can be seen in some medical imaging studies of the brain, and also in dissections in which the brain is opened up to reveal the structures inside. The functions of various structures can be highlighted with the use of stains which attach to various types of tissue or chemicals found in the brain, allowing people to clearly differentiate between structures which might otherwise be difficult to identify.