Reaching to, and grasping visual targets is an important class of movements that requires transformations of spatial information between visual and kinesthetic coordinates. Patients with lesions of the posterior parietal cortex exhibit difficulties in reaching that are likely due to errors in visual, or kinesthetic perceptions, or in sensorimotor transformations. The proposed research involves studies of these perceptions and transformations in such patients, with a focus on lesions limited to the superior and inferior parietal cortex, and age-matched patients with occipital cortex lesions and age-matched control subjects.
The Specific Aims are to determine: (1) the directions of kinesthetic coordinate axes; (2) the directions of visual coordinate axes; 3) the errors associated with sensorimotor transformations for target reaching tasks; and 4) the influence of head orientation on errors in reaching. It is suggested by the applicant that the knowledge gained from these studies should find application to the diagnosis and rehabilitation of stroke patients. A better understanding of the roles of different sensory systems and cognitive perceptions in control of reaching could lead to development of new techniques to enhance performance of upper limb movements.

National Institute of Health (NIH)
National Institute of Neurological Disorders and Stroke (NINDS)
Research Project (R01)
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Special Emphasis Panel (ZRG4-ORTH (04))
Program Officer
Marler, John R
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University of Iowa
Other Health Professions
Schools of Arts and Sciences
Iowa City
United States
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Darling, Warren G; Bartelt, Robert; Pizzimenti, Marc A et al. (2008) Spatial perception errors do not predict pointing errors by individuals with brain lesions. J Clin Exp Neuropsychol 30:102-19
Darling, Warren G; Robert, Bartelt (2005) The visual perception coordinate system uses axes defined by the earth, trunk, and vision. Perception 34:17-30
Darling, W G; Bartelt, R; Rizzo, M (2004) Unilateral posterior parietal lobe lesions disrupt kinaesthetic representation of forearm orientation. J Neurol Neurosurg Psychiatry 75:428-35
Darling, Warren G; Bartelt, Robert (2003) Kinesthetic perception of visually specified axes. Exp Brain Res 149:40-7
Darling, Warren G; Pizzimenti, Marc A; Rizzo, Matthew (2003) Unilateral posterior parietal lobe lesions affect representation of visual space. Vision Res 43:1675-88
Bartelt, Robert; Darling, Warren G (2002) Opposite effects on perception and action induced by the Ponzo illusion. Exp Brain Res 146:433-40
Darling, W G; Rizzo, M; Butler, A J (2001) Disordered sensorimotor transformations for reaching following posterior cortical lesions. Neuropsychologia 39:237-54
Darling, W G; Pizzimenti, M A (2001) A coordinate system for visual motion perception. Exp Brain Res 141:174-83
Darling, W G; Rizzo, M (2001) Developmental lesions of visual cortex influence control of reaching. Neuropsychologia 39:346-51
Darling, W G; Hondzinski, J M; Harper, J G (2000) Gaze direction effects on perceptions of upper limb kinesthetic coordinate system axes. Exp Brain Res 135:360-72

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