Dynamics of Digit Tremor Within and Between Hands

Open Access
Author:
Yu, Ping
Graduate Program:
Kinesiology
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
February 27, 2012
Committee Members:
  • Karl Maxim Newell, Thesis Advisor
Keywords:
  • Digit tremor
  • Dynamics
  • Coherence
Abstract:
Tremor is a very low amplitude involuntary oscillatory-like limb motion that is barely visible to the naked eye but present in all individuals. In this study, we investigated the tremor dynamics of digits within and across hands that occurred under both 0 degree postural angle and 30 degree postural angle crossed with eyes open and eyes closed conditions. Twelve healthy young adults participated in the study (4 conditions, 12 trials/condition, 30s/trial) and accelerometers were used to measure digit tremor. Amplitude analysis showed that the 30 degree posture angle increased the magnitude of acceleration regardless of vision condition. Visual information increased tremor amplitude of the left hand but not the right hand digits. Tremor amplitude was greater in the index finger and progressively smaller in the middle, ring and little fingers. Approximate Entropy (ApEn) showed that the higher postural angle led to greater tremor irregularity. The coupling of the tremor of the index and middle fingers was highest and the level of the coupling within hand decreased as the relative adjacency of digits from each other increased. There was no evidence of tremor coupling in the homologous digits across hands. Postural angle of the digits and the availability of visual information modestly changed the scaling of the tremor dynamics. It is concluded that the anatomical and physiological structures are the primary influence on the tremor dynamics of amplitude and coupling within and between digits of the hands.