Lisäaivokuori

Lisäaivokuori, also known as the supplementary motor area (SMA), is a region of the cerebral cortex located in the frontal lobe of the brain, anterior to the primary motor cortex. It plays a crucial role in the planning and sequencing of movements, particularly those that are internally generated or complex. Unlike the primary motor cortex which directly executes movements, the SMA is involved in higher-level motor control.

Research suggests the SMA is involved in preparing for movement, selecting appropriate motor programs, and coordinating bimanual actions. It receives input from various brain regions, including the prefrontal cortex and basal ganglia, and projects to the primary motor cortex and brainstem motor nuclei. Studies using neuroimaging techniques like fMRI have shown increased SMA activity during tasks requiring motor planning, imagination of movements, and the learning of new motor skills.

Damage to the SMA can result in a range of motor deficits, including apraxia, which is difficulty performing learned, purposeful movements despite intact motor and sensory function. It can also affect the ability to initiate voluntary movements and the coordination of complex motor sequences. The SMA is therefore a key component of the brain's motor system, contributing significantly to our ability to plan and execute a wide variety of actions.