Fig. 3.
A and B: linear regression analysis of the BOLD signal change in the left (contralateral) putamen for both sustained (A) and cyclic (B) compression tasks. There is a statistically significant increase in signal intensity with increasing dexterity index (more unstable springs). C: piecewise polynomial fit of regression coefficients of the BOLD signal change in the left (contralateral) ventral premotor cortex (vPM; inferior frontal gyrus). There is a significant increase in signal intensity between springs 2 and 3 (dexterity index 0.65 and 0.92), suggesting a step function type response.