The Brain and Motor Control: Pathways, Pathophysiology and a History of Experimentation

Abstract

The control of movement is complex. A motor plan is formed with the involvement of the primary motor cortex, the supplementary motor areas and other brain structures such as the basal ganglia and cerebellum. This plan is encoded into electrical signals which are propagated along many neurons in the form of action potentials. These signals travel from layer V of the primary motor cortex through the pyramidal tract to the upper motor neuron and interneurons of the spinal cord. Motoneurons carry the signals out through the ventral horn of the spinal cord through the periphery to the neuromuscular junction at the muscle cell. A series of events here ultimately result in contraction. Injuries to the brain and spinal cord can cause a myriad of motor symptoms. Disorders such as Multiple Sclerosis, Amyotrophic Lateral Sclerosis, Parkinson’s Disease and Huntington’s Disease also have motor symptoms caused by various pathophysiologies occurring at the cellular level. These symptoms can usually be alleviated with pharmacological intervention. A brief history of central nervous system experimentation from 1870 to present is also discussed.