Aging, Neuromuscular Decline, and the Change in Physiological and Behavioral Complexity of Upper-Limb Movement Dynamics
Figure 2
Representative postural acceleration (tremor) traces and power spectral profiles from the index finger of a healthy young and an elderly subject. Traces for each person are shown for conditions where (a) only the finger was extended (the rest of the upper limb was externally supported) and (b) when the entire upper arm was unsupported. Tremor traces were obtained from a single trial for the index finger of each individual. Measures of the degree of regularity (ApEn) of each tremor signal are also shown for each condition. For this analysis, higher values reflect greater complexity within the tremor time series. This example highlights that the age-related differences in finger tremor were only present under conditions where the entire arm was held against gravity.
