Figure 5.

Relating neural and behavioral drift magnitudes. a, Correlation across sessions and targets between the amounts of variability attributable to drift in reach speed and in preparatory neural activity. b, Analogous to a but comparing residual trial-to-trial variability instead of variability attributable to drift. c, d, Analogous to a and b but with reach direction as the behavioral variable. In all panels, the behavioral variability is expressed as SD; neural variability is expressed as coefficient of variation (SD/mean), averaged across all neurons. All values are mean subtracted for matched experimental conditions (see text). The gray trace shows the regression slope for both monkeys combined. For both behavioral metrics, the magnitude of behavioral drift correlates positively with the magnitude of neural drift for each monkey (a, c) and is significant with both monkeys combined (p < 0.05, t test).