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The posterior cerebellum, the largest lobe of the cerebellum, is the portion located below the primary fissure in this part of the brain. It is the most recently evolved part of the cerebellum, found only in mammals. In humans, it is located at the bottom of the cerebellum, near the medulla and spinal cord. The primary function of this lobe of the brain is fine tuning movements. Also referred to as the neocerebellum, this area plays a role in planning and executing movement in coordination with other areas of the brain.
As with other parts of the cerebellum, most activity in the posterior cerebellum is believed to occur without conscious thought. It has long been known as the area of the brain that controls the amount of force, the direction, and other intricacies of movement. A loop of neural connections between this lobe of the brain and the cerebral cortex regulate movement, maintaining its precision. Information from the eyes, ears and muscles is received in a part of the posterior cerebellum, helping with coordination. This information lets the posterior cerebellum coordinate movements to changing conditions, allowing quick responses.
In addition to controlling the fine aspects of movement, this lobe of the brain also initiates and stops the movement. This timing of movement gives mammals more precision during important activities such as hunting or evading predators. The posterior cerebellum is also intimately involved in learning new movements and perfecting them. Whether it is a baby learning to walk or an athlete practicing a new maneuver, this part of the brain is essential in perfecting new motor skills.
Damage to the posterior cerebellum may result in a lack of coordination. The movement may be badly timed, directed, or have irregular rhythm. Involuntary movements may increase, as this lobe of the brain also prevents unnecessary movements. Injuries, strokes or diseases affecting the posterior cerebellum may result in a loss of balance and the inability to remain stationary and steady. A person suffering from cerebellum damage may appear drunk.
Through studying the effects of damage to or abnormalities in the cerebellum, researchers have learned more about the functions of this part of the brain. They believe the posterior cerebellum may be active in some cognitive and behavioral functions. Cognitive functions such as working memory, the ability to recall words, and planning are impaired when the this part of the brain is damaged. Studies have found that some patients with autism and attention deficit hyperactivity disorder (ADHD) have smaller than normal posterior cerebellums, possibly indicating a broader role for this lobe of the brain in cognition and behavior.