putamen

The putamen is a large subcortical structure that forms the lateral part of the lentiform nucleus, together with the globus pallidus. It is part of the basal ganglia and, with the caudate nucleus, makes up the striatum. The putamen lies deep within the cerebral hemispheres and is typically separated from the caudate nucleus by the anterior limb of the internal capsule.

Anatomy and connections: The putamen receives extensive input from the cerebral cortex, especially motor and somatosensory areas, and from thalamic nuclei. It projects to the globus pallidus internus and substantia nigra reticulata via the striato-pallidal pathways. The basal ganglia circuits then influence thalamocortical activity to modulate movement and behavior. The dorsal portion of the putamen is primarily associated with sensorimotor functions, while ventral aspects interact with limbic and cognitive networks.

Function and physiology: The putamen participates in regulation of voluntary movement, motor planning, and procedural learning. It processes reward-related and motivational information integrated with motor activity. The principal neurons are medium spiny neurons, which are GABAergic and modulated by dopaminergic input from the substantia nigra pars compacta through direct and indirect pathways.

Clinical relevance: Degeneration of the striatum, including the putamen, occurs in Huntington’s disease and contributes to chorea and cognitive changes. Parkinson’s disease features dopaminergic loss that affects putaminal circuits, contributing to bradykinesia and rigidity. Lesions or dysfunction can impair motor control, and imaging typically shows basal ganglia involvement in these conditions.

Development and organization: The putamen develops with the other basal ganglia structures from the telencephalon and remains closely connected to the caudate nucleus as part of the striatum.