Mechanisms of human cerebellar dysmetria: experimental evidence and current conceptual bases

J Neuroeng Rehabil. 2009 Apr 13;6:10. doi: 10.1186/1743-0003-6-10.

Abstract

The human cerebellum contains more neurons than any other region in the brain and is a major actor in motor control. Cerebellar circuitry is unique by its stereotyped architecture and its modular organization. Understanding the motor codes underlying the organization of limb movement and the rules of signal processing applied by the cerebellar circuits remains a major challenge for the forthcoming decades. One of the cardinal deficits observed in cerebellar patients is dysmetria, designating the inability to perform accurate movements. Patients overshoot (hypermetria) or undershoot (hypometria) the aimed target during voluntary goal-directed tasks. The mechanisms of cerebellar dysmetria are reviewed, with an emphasis on the roles of cerebellar pathways in controlling fundamental aspects of movement control such as anticipation, timing of motor commands, sensorimotor synchronization, maintenance of sensorimotor associations and tuning of the magnitudes of muscle activities. An overview of recent advances in our understanding of the contribution of cerebellar circuitry in the elaboration and shaping of motor commands is provided, with a discussion on the relevant anatomy, the results of the neurophysiological studies, and the computational models which have been proposed to approach cerebellar function.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Action Potentials
  • Animals
  • Biomechanical Phenomena
  • Cerebellar Ataxia / physiopathology*
  • Cerebellum / anatomy & histology
  • Cerebellum / physiology
  • Cerebellum / physiopathology*
  • Humans
  • Learning / physiology
  • Models, Neurological
  • Motor Activity / physiology*
  • Muscle, Skeletal / physiology
  • Neurons / physiology
  • Time Factors