Interlimb Differences in Wrist Diodochokinesis Are Most Pronounced Perpendicular to the Instructed Motion, and are not Attenuated during Bilateral Performance

Open Access
Srinivasan, Gautum Ayush
Graduate Program:
Master of Science
Document Type:
Master Thesis
Date of Defense:
May 24, 2018
Committee Members:
  • Dr. Robert Sainburg, Thesis Advisor
  • Dr. Mark Latash, Committee Member
  • Dr. Jonas Rubenson, Committee Member
  • Diadochokinesis
  • Radial-Ulnar Wrist Deviation
  • Bilateral
  • Bilateral Coordination
  • Coordination
  • Motor Control
  • Unilateral Coordination
  • Unilateral
  • Metronome
  • Partial Visual Feedback
Previous research has demonstrated differences in multi-joint and single segment coordination between dominant and non-dominant hands. This research examines differences in coordination of rapid, radial/ulnar wrist deviation (RUD) between the two arms both unilaterally and bilaterally. We hypothesize that the dominant hemisphere is specialized for predicting inter/intra-segmental dynamics. To test this hypothesis, two studies were conducted; the first tests for interlimb difference during RUD with the participants’ forearm supported, no visual feedback and two speeds of movement: “Slow” and “As fast as possible”. In the second study, the task was performed at 0.5Hz, 1Hz and 2Hz, participants were given visual feedback of their finger position in the horizontal (instructed) plane, via a cursor and asked to move the cursor between two targets while attempting to restrict motion to RUD. Additionally, participants were asked to perform the task unilaterally and bilaterally. Participants’ movements were assessed in three dimensions across 3 degrees of freedom: Forearm pronation/supination, wrist ulnar/radial deviation, and wrist flexion/extension. We predicted substantial interlimb differences in the fast condition in study 1 and during the unilateral phase in study two with a dependence on frequency (i.e. more asymmetries with increasing frequency). We also predict an attenuation of asymmetries during the bilateral condition. Results from study 1 show greater recruitment of uninstructed degrees of freedom in the non-dominant hand during the fast condition. Results from study 2 bolster results from study 1 with the non-dominant hand recruiting more uninstructed motion and maintaining a frequency dependence. Specifically, non-dominant wrist movements were characterized by circumduction, producing circular paths in the frontal plane, whereas dominant wrist movements were more linear. Additionally, the bilateral condition did not attenuate any of the asymmetries. We have interpreted these results as displaying a specialization of the dominant hand to predict how the intra-wrist dynamics will change during this rapid motion and the non-dominant controller’s strategy becoming less effective at controlling uninstructed movement at higher frequencies. Secondly. these interlimb differences seem to be robust regardless of unilateral or bilateral performance.