Journal article
Reaching with cerebral tunnel vision
Neuropsychologia, Vol.35(1), pp.53-63
1997
DOI: 10.1016/S0028-3932(96)00053-X
PMID: 8981377
Abstract
We studied reaching movements in a 48-year-old man with bilateral lesions of the calcarine cortex which spared the foveal representation and caused severe tunnel vision. Three-dimensional (3D) reconstruction of brain MR images showed no evidence of damage beyond area 18. The patient could not see his hand during reaching movements, providing a unique opportunity to test the role of peripheral visual cues in limb control. Optoelectronic recordings of upper limb movements showed normal hand paths and trajectories to fixated extrinsic targets. There was no slowing, tremor, or ataxia. Self-bound movements were also preserved. Analyses of limb orientation at the endpoints of reaches showed that the patient could transform an extrinsic target's visual coordinates to an appropriate upper limb configuration for target acquisition. There was no disadvantage created by blocking the view of the reaching arm. Moreover, the patient could not locate targets presented in the hemianopic fields by pointing. Thus, residual nonconscious vision or `blindsight' in the aberrant fields was not a factor in our patient's reaching performance. The findings in this study show that peripheral visual cues on the position and velocity of the moving limb are not critical to the control of goal directed reaches, at least not until the hand is close to target. Other cues such as kinesthetic feedback can suffice. It also appears that the visuomotor transformations for reaching do not take place before area 19 in humans.
Details
- Title: Subtitle
- Reaching with cerebral tunnel vision
- Creators
- Matthew Rizzo - University of IowaWarren Darling - University of Iowa
- Resource Type
- Journal article
- Publication Details
- Neuropsychologia, Vol.35(1), pp.53-63
- Publisher
- Elsevier Ltd
- DOI
- 10.1016/S0028-3932(96)00053-X
- PMID
- 8981377
- ISSN
- 0028-3932
- eISSN
- 1873-3514
- Language
- English
- Date published
- 1997
- Academic Unit
- Neurology; Physical Therapy and Rehabilitation Science; Health and Human Physiology
- Record Identifier
- 9984259641502771
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