[Abstract Title]. - Society for Neuroscience

DC; 4 District Amputee Care, Washington, DC; 5 Rehab Med. & Neurol, Natl. Rehab Hosp,
Washington, DC
Abstract: This study investigated the role of vision in upper extremity reaching movements of
unilateral below elbow prosthetic users. Subjects used a robotic manipulandum to reach to two
targets, one contralateral and one ipsilateral, located in a horizontal plane. These trials were
performed with both the prosthetic arm and the intact arm. Visual guidance was then eliminated
from the environment and the subjects had to reach to the same targets, relying on their sense of
proprioception. Endpoint error, trajectory error and variability were calculated and compared to
that of control subjects. We predicted that performance of the prosthetic device would be less
accurate than controls and that the intact arm would be comparable to normal performance.
Contrary to our hypothesis, results showed no significant difference between the performance of
the prosthetic arm and the controls in the vision and no-vision conditions. Analysis did however
reveal significant abnormalities in performance of the intact limb. When compared to controls,
the intact arm of the prosthetic users had significantly larger medial endpoint errors for the
ipsilateral target without visual guidance (P = 0.001). This was consistent with data from the
intact arm in the vision condition, where a significantly larger medial trajectory error (P = 0.003)
was found. In the vision condition, this trajectory error was corrected with visual feedback,
which allowed the subjects to correct their errors and complete the reach without endpoint error.
The intact arms also demonstrated significantly higher variability in their reaching endpoints in
the no-vision condition. (P = 0.010). These findings regarding the prosthetic arm reveal an
adaptation to the altered inertial properties of the arm. The findings regarding the intact arm may
reflect the cortical reorganization that occurs after amputation of a limb, which is consistent with
recent theories regarding hemispheric lateralization of motor control.
Disclosures: A.J. Metzger, None; P.S. Lum, None; C.N. Schabowsky, None; R.J. Holley,
None; B. Monroe, None; A.W. Dromerick , None.
Poster
262. Visually-Guided Reaching II
Time: Sunday, November 16, 2008, 1:00 pm - 5:00 pm
Program#/Poster#: 262.20/CC34
Topic: D.05.c. Eye-hand coordination
Support: Dutch Neurofibromatosis Foundation
Sophia Foundation for Medical Research
Hersenstichting Nederland