Role of posterior parietal cortex in the recalibration of visually guided reaching

• Published in: Nature (London) Vol. 383; no. 6601; pp. 618 - 621
• Main Authors: Clower, Dottie M., Hoffman, John M., Votaw, John R., Faber, Tracy L., Woods, Roger P., Alexander, Garrett E.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 17.10.1996; Nature Publishing; Nature Publishing Group
• Subjects: Adaptation, Physiological; Afterimage; Biological and medical sciences; Blood; Brain; Brain Mapping; Cerebrovascular Circulation; Emissions; Eyes & eyesight; Fundamental and applied biological sciences. Psychology; Hand - physiology; Humanities and Social Sciences; letter; Motor control and motor pathways. Reflexes. Control centers of vegetative functions. Vestibular system and equilibration; multidisciplinary; Neurology; Ocular Physiological Phenomena; Parietal Lobe - physiology; Psychomotor Performance - physiology; Science; Science (multidisciplinary); Sensory perception; Tomography, Emission-Computed; Vertebrates: nervous system and sense organs; Visual Perception - physiology; Human; Sensorimotor coordination; Vision; Central nervous system; Parietal cortex; Body movement; Goal directed movement; Feedback regulation; Eye head coordination; Brain (vertebrata); Adaptation
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/383618a0

VISUALLY guided reaching requires complex neural transformations to link visual and proprioceptive inputs with appropriate motor outputs 1,2 . Despite the complexity of these transformations, hand–eye coordination in humans is remarkably flexible, as demonstrated by the ease with which reaching can be adapted to distortions in visual feedback. If subjects attempt to reach to visual targets while wearing displacing prisms, they initially misreach in the direction of visual displacement. Given feedback about their reaching errors, however, they quickly adapt to the visual distortion. This is shown by the gradual resumption of accurate reaching while the prisms remain in place, and by the immediate onset of reaching errors in the opposite direction after the prisms have been removed 3 . Despite an abundance of psy-chophysical data on adaptation to prisms, the functional localization of this form of sensorimotor adaptation is uncertain. Here we use positron emission tomography (PET) to localize changes in regional cerebral blood flow (rCBF) in subjects who performed a prism-adaptation task as well as a task that controlled for the sensory, motor and cognitive conditions of the adaptation experiment. Difference images that reflected the net effects of the adaptation process showed selective activation of posterior parietal cortex contralateral to the reaching limb.