How can basal ganglia disorders affect memory and motivation as well as movement?

The basal ganglia are primarily known for fine-tuning movement, but they also play a critical role in cognitive and motivational processes. Dysfunction in these structures affects these areas through the following mechanisms:

• Movement: The basal ganglia act as gatekeepers in action selection, amplifying signals for desired movements while suppressing unwanted ones. Disorders like Parkinson disease (characterized by hypokinesia) or Huntington disease (hyperkinesia) arise when specific neuronal populations are lost, disrupting the firing patterns within the brain's parallel pathways.123
• Motivation: Dopamine neurons in the basal ganglia are essential for providing the drive to interact with and learn from the environment. By releasing pulses of dopamine, these neurons reinforce pathways associated with rewarding outcomes, effectively teaching the brain which actions to prioritize. When this neurochemical activity is abnormal, it can lead to impaired motivation.23
• Memory: The basal ganglia contribute to cognitive functions, including reasoning and memory, by helping the brain learn new actions and form habits. Because they are involved in reinforcing specific motor and behavioral pathways, their dysfunction can disrupt the cognitive processes required for goal-directed tasks.3142