Figure 7. Neural activity displays an orderly transition from the preparatory subspace to the movement subspace.
(a) Neural state trajectory during the transition from preparation to movement. Each trace plots the trajectory for one (of eight) reach directions. Axes correspond to the top preparatory dimension and the top two movement dimensions. Stars denote the neural state 200 ms before movement onset. Dotted lines denote the neural trajectories during the transition, over the next 200 ms, from the preparatory dimension to the movement dimensions. Solid lines denote the trajectories during the 50 ms following movement onset. (b) The same space as in a rotated to show only the two movement dimensions. (c) Quality of fit (R2) of the regression between the responses in the movement subspace (at the middle of movement epoch; 100 ms after movement onset) and the responses in the preparatory subspace (at the end of the preparatory epoch; 450 ms after target onset). (d) Leave-one-out cross-validation (LOOCV) for that same relationship. Stars in c and d denote a significantly higher R2 than shuffled data (P<0.001, one-tailed test). The shuffled data were generated by randomly shuffling the preparatory-epoch responses across conditions. In both c and d, bars show the median and error bars denote the 95% confidence interval of the shuffled distribution with 1,000 random shuffles.