The human brain is the most complex organ in the body. Rapid events occur within the brain that allow you to interact with your environment. Reaching to grasp a cup of coffee seems like an easy task. However, the underlying cortical processes required tell a different story. Areas such as the posterior parietal cortex, premotor cortex, dorso-lateral prefrontal cortex and primary motor cortex mediate specific calculations to plan and execute movement, according to the California Institute of Technology.
Posterior Parietal Cortex
The posterior parietal cortex, or PPC, receives sensory input from the body, joints and visual system. The PPC uses sensory information to determine the position of the body in space and the location of objects in the environment. Based on the body and object location calculations, the PPC creates a model and sends the model to the areas of the brain responsible for movement planning, according to McGill University.
Prefrontal Cortex
A region of the prefrontal cortex called the dorso-lateral prefrontal cortex, or DLPFC, plays a role in higher-order cognitive functions such as decision-making, attention, movement planning and working memory. The DLPFC enables you to decide when to make a movement based on sensory information and emotional response. Without the DLPFC, you would be unable to decide what action to make, according to University of Colorado at Boulder.
Premotor Cortex
The premotor cortex is divided into lateral and medial regions. The lateral premotor cortex plans the timing, direction or sequence of movements, primarily in response to an external cue--for example, a light or auditory stimulus. Conversely, the medial premotor cortex, also called the supplementary motor area, plans the timing, direction and sequence of movements as well, but to internally driven movement, according to the National Center for Biotechnology Information.
Primary Motor Cortex
The movement plan, formed by the PPC, DLPFC and premotor cortex, is sent to the primary motor cortex, or M1. The M1 executes the movement plan by stimulating the spinal nerves that activate the muscles of the body. In the early 1950s, Dr. Wilder Penfield discovered that stimulation of the M1 produces muscle movement on the opposite side of the body. Additionally, the M1 is organized in a precise manner with specified areas dedicated to each area of the body, according to McGill University.
