Experimental Brain Research

, Volume 168, Issue 1, pp 186–202

Hand preshaping in Parkinson’s disease: effects of visual feedback and medication state

  • Luis F. Schettino
  • Sergei V. Adamovich
  • Wayne Hening
  • Eugene Tunik
  • Jacob Sage
  • Howard Poizner
Research Article

DOI: 10.1007/s00221-005-0080-4

Cite this article as:
Schettino, L.F., Adamovich, S.V., Hening, W. et al. Exp Brain Res (2006) 168: 186. doi:10.1007/s00221-005-0080-4
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Abstract

Previous studies in our laboratory examining pointing and reach-to-grasp movements of Parkinson’s disease patients (PDPs) have found that PDPs exhibit specific deficits in movement coordination and in the sensorimotor transformations required to accurately guide movements. We have identified a particular difficulty in matching unseen limb position, sensed by proprioception, with a visible target. In the present work, we further explored aspects of complex sensorimotor transformation and motor coordination using a reach-to-grasp task in which object shape, visual feedback, and dopaminergic medication were varied. Normal performance in this task requires coordinated generation of appropriate reach, to bring the hand to the target, and differentiated grasp, to preshape the hand congruent with object form. In Experiment 1, we tested PDPs in the off-medication state. To examine the dependence of subjects on visual feedback and their ability to implement intermodal sensory integration, we required them to reach and grasp the target objects in three conditions: (1) Full Vision, (2) Object Vision with only the target object visible and, (3) No Vision with neither the moving arm nor the target object visible. PDPs exhibited two types of deficits. First, in all conditions, they demonstrated a generalized slowing of movement or bradykinesia. We consider this an intensive deficit, since it involves largely a modulation of the gain of specific task parameters: in this case, velocity of movement. Second, they were less able than controls to extract critical proprioceptive information and integrate it with vision in order to coordinate the reach and grasp components of movement. These deficits which involve the coordination of different inputs and motor components, we classify as coordinative deficits. As in our previous work, the PDPs’ deficits were most marked when they were required to use proprioception to guide their hand to a visible target (Object Vision condition). But even in the full-vision condition, their performance only became fully accurate when both the target and effector (hand) were simultaneously visible. In Experiment 2, PDPs were tested on their dopaminergic replacement therapy. Dopaminergic treatment significantly ameliorated the bradykinesia of the PDPs, but produced no changes in the hand preshaping deficiencies of PDPs. These results suggest that adequate treatment of the PDPs may more readily compensate for intensive, than coordinative deficits, since the latter are likely to depend on specific and time-dependent neural interdependencies that are unlikely to be remediated simply by increasing the gain of a pathway.

Keywords

Parkinson’s disease Grasping Hand preshaping Dopamine-replacement therapy Visuomotor control 

Copyright information

© Springer-Verlag 2005

Authors and Affiliations

  • Luis F. Schettino
    • 1
  • Sergei V. Adamovich
    • 2
  • Wayne Hening
    • 3
  • Eugene Tunik
    • 4
  • Jacob Sage
    • 3
  • Howard Poizner
    • 5
  1. 1.Department of PsychologyTrinity UniversitySan AntonioUSA
  2. 2.Department of Biomedical EngineeringNew Jersey Institute of TechnologyNewarkUSA
  3. 3.Department of NeurologyUMDNJ-R.W. Johnson Medical SchoolNew BrunswickUSA
  4. 4.Department of Psychological and Brain SciencesDarmouth CollegeHanoverUSA
  5. 5.Institute for Neural ComputationUniversity of CaliforniaSan Diego LaJollaUSA

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