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Grip forces isolated from knowledge about object properties following a left parietal lesion
Yong Li1, Jennifer Randerath, Georg Goldenberg
1Clinical Neuropsychology Research Group (EKN), Academic Hospital Munich-Bogenhausen, Technical University of Munich, Dachauerstr. 164, D-80992 Munich, Germany. Yong.Li@extern.lrz-muenchen.de
Neuroscience Letters
|October 2, 2007
Summary
The posterior parietal cortex (PPC) is crucial for scaling grip forces based on object size. Damage to the left PPC impairs this scaling and affects the size-weight illusion, particularly with the ipsilesional hand.
Area of Science:
- Neuroscience
- Human motor control
- Perception
Background:
- The size-weight illusion, where smaller objects are perceived as heavier, is well-documented.
- Anticipatory grip force scaling to object size is a key sensorimotor adaptation.
- The role of the posterior parietal cortex (PPC) in integrating perceptual and sensorimotor predictions is not fully understood.
Purpose of the Study:
- To investigate the dependency of anticipatory grip force scaling on the posterior parietal cortex (PPC).
- To examine how PPC integrity influences the size-weight illusion.
- To analyze the sensorimotor and perceptual consequences of a left temporal-parietal lesion.
Main Methods:
- Case study of a patient (F.S.) with a left temporal-parietal lesion and limb apraxia.
- Comparison of F.S. with matched controls during precision lifting tasks.
- Assessment of fingertip grip force scaling and perception of the size-weight illusion.
Main Results:
- Patient F.S. lacked anticipatory grip force scaling to object size, unlike controls.
- F.S. exhibited an impaired size-weight illusion perception, but only when using his ipsilesional (left) hand.
- The patient's limb apraxia suggests broader sensorimotor deficits.
Conclusions:
- The left parietal cortex is critical for anticipatory grip force scaling for both hands.
- The left parietal cortex plays a role in the perceptual size-weight illusion, especially for ipsilesional hand movements.
- Sensorimotor and perceptual aspects of the size-weight illusion may involve distinct but interacting neural pathways within the PPC.
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