Neural space analysis, semantic task (ST). (a,b) Trajectories in the 3D “neural space” formed by the first three principal components of PCA, during the semantic task (ST) performed by M3 (a) and M4 (b). The neural trajectories span the interval [−500, 800], with zero being the target onset, and each bin representing the average of 200 ms. Circles mark the beginning of the neural trajectories, crosses mark target onset, and squares mark the end of the neural trajectories. (c,d) Trajectories in the 1D space of the first 4 components of PCA (one panel for each component) for M3 and M4, respectively. Mean (colored line) and variance (colored shades) are shown.