Individual fingertip contact points and covariation of digit pair contact points.

<p>Panel A depicts fingertip vertical location relative to the base of the cylinder for each digit as a function of CM location and predictability condition for controls and PD patients (left and right columns, respectively). The scale of the vertical axes is the same for all plots to allow comparison across digits. Data are means ± SE of all subjects. Asterisks denote a significant difference at <i>p</i><0.05. Panel B represents the magnitude of the correlation coefficient (Pearson's <i>r</i>) of digit pair contact points for the controls and PD patients (top and bottom polar plots, respectively). The <i>r</i>-values shown in each polar plot were averaged across all subjects (after z-normalization). Values nearing zero, i.e., closer to the center of the polar plot, represent greater independence of digit pair contact points than values nearing one. White and black circles denote random and blocked conditions, respectively. T, I, M, R and L denote thumb, index, middle, ring and little fingers, respectively. Note that for digit pair correlations with similar values for blocked and random, it may appear as a single white circle.