An 'automatic pilot' for the hand in human posterior parietal cortex: toward reinterpreting optic ataxia

Nat Neurosci. 2000 Jul;3(7):729-36. doi: 10.1038/76694.


We designed a protocol distinguishing between automatic and intentional motor reactions to changes in target location triggered at movement onset. In response to target jumps, but not to a similar change cued by a color switch, normal subjects often could not avoid automatically correcting fast aiming movements. This suggests that an 'automatic pilot' relying on spatial vision drives fast corrective arm movements that can escape intentional control. In a patient with a bilateral posterior parietal cortex (PPC) lesion, motor corrections could only be slow and deliberate. We propose that 'on-line' control is the most specific function of the PPC and that optic ataxia could result from a disruption of automatic hand guidance.

Publication types

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

MeSH terms

  • Adult
  • Ataxia / pathology
  • Ataxia / physiopathology*
  • Brain Mapping*
  • Cues
  • Female
  • Hand / innervation*
  • Humans
  • Magnetic Resonance Imaging
  • Motor Activity
  • Parietal Lobe / pathology
  • Parietal Lobe / physiology*
  • Parietal Lobe / physiopathology*
  • Psychomotor Performance / physiology*
  • Reaction Time
  • Space Perception / physiology*