FULL PAPER: Teulings_ContrerasVidal_Stelmach_Adler_ExperimentalNeurology1997.pdf

EXPERIMENTAL NEUROLOGY 146, 159–170 (1997)

Parkinsonism Reduces Coordination of Fingers, Wrist,
and Arm in Fine Motor Control

Hans-Leo Teulings, Jose´ L. Contreras-Vidal, George E. Stelmach, and Charles H. Adler*
Motor Control Laboratory, Arizona State University, Tempe, Arizona 85287-0404; and *Mayo Clinic, Scottsdale, Arizona 85259
This experiment investigates movement coordination
in Parkinson’s disease (PD) subjects. Seventeen
PD patients and 12 elderly control subjects performed
several handwriting-like tasks on a digitizing writing
tablet resting on top of a table in front of the subject.
The writing patterns, in increasing order of coordination
complexity, were repetitive back-and-forth movements
in various orientations, circles and loops in
clockwise and counterclockwise directions, and a complex
writing pattern. The patterns were analyzed in
terms of jerk normalized for duration and size per
stroke. In the PD subjects, back-and-forth strokes,
involving coordination of fingers and wrist, showed
larger normalized jerk than strokes performed using
either the wrist or the fingers alone. In the PD patients,
wrist flexion (plus radial deviation) showed greater
normalized jerk in comparison to wrist extension (plus
ulnar deviation). The elderly control subjects showed
no such effects as a function of coordination complexity.
For both PD and elderly control subjects, looping
patterns consisting of circles with a left-to-right forearm
movement, did not show a systematic increase of
normalized jerk. The same handwriting patterns were
then simulated using a biologically inspired neural
network model of the basal ganglia thalamocortical
relations for a control and a mild PD subject. The
network simulation was consistent with the observed
experimental results, providing additional support that
a reduced capability to coordinate wrist and finger
movements may be caused by suboptimal functioning
of the basal ganglia in PD. The results suggest that in
PDpatients fine motor control problems may be caused
by a reduced capability to coordinate the fingers and
wrist and by reduced control of wrist flexion. r 1997
Academic Press