The basal ganglia, a group of subcortical nuclei, play a critical role in movement control. Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra, particularly in the posterior putamen, leading to impaired habitual control. Patients with PD may rely more on goal-directed control, which is less affected by dopamine loss. The basal ganglia are divided into functionally distinct territories, with the rostromedial striatum involved in goal-directed actions and the caudolateral striatum in habitual actions. Dysfunction in these regions can lead to motor deficits, including bradykinesia and tremors. The basal ganglia are connected to the cerebral cortex and brainstem through complex loops, enabling the selection of goal-directed or habitual actions. Lesions in the basal ganglia, such as those in the subthalamic nucleus or globus pallidus, can disrupt movement control, leading to conditions like hemiballismus. In PD, the loss of dopamine disrupts the balance between goal-directed and habitual control, leading to impaired automatic behaviors. Surgical interventions targeting the basal ganglia, such as deep brain stimulation, can alleviate symptoms by reducing dysfunctional output. The dual control systems of the basal ganglia—goal-directed and habitual—operate through regionally segregated circuits, and their dysfunction contributes to the motor and cognitive symptoms of PD. Understanding these systems is crucial for developing effective treatments for PD and other movement disorders.The basal ganglia, a group of subcortical nuclei, play a critical role in movement control. Parkinson's disease (PD) is characterized by the progressive loss of dopaminergic neurons in the substantia nigra, particularly in the posterior putamen, leading to impaired habitual control. Patients with PD may rely more on goal-directed control, which is less affected by dopamine loss. The basal ganglia are divided into functionally distinct territories, with the rostromedial striatum involved in goal-directed actions and the caudolateral striatum in habitual actions. Dysfunction in these regions can lead to motor deficits, including bradykinesia and tremors. The basal ganglia are connected to the cerebral cortex and brainstem through complex loops, enabling the selection of goal-directed or habitual actions. Lesions in the basal ganglia, such as those in the subthalamic nucleus or globus pallidus, can disrupt movement control, leading to conditions like hemiballismus. In PD, the loss of dopamine disrupts the balance between goal-directed and habitual control, leading to impaired automatic behaviors. Surgical interventions targeting the basal ganglia, such as deep brain stimulation, can alleviate symptoms by reducing dysfunctional output. The dual control systems of the basal ganglia—goal-directed and habitual—operate through regionally segregated circuits, and their dysfunction contributes to the motor and cognitive symptoms of PD. Understanding these systems is crucial for developing effective treatments for PD and other movement disorders.