The evolving representation of trial events can be visualized by projecting the average neuronal activity for each trial type (defined by choice, second-step state, and outcome) into the low dimensional space that captures the greatest variance between different trial types (see STAR Methods) (Figure 4). The first three principal components (PCs) of this space were dominated by representation of choice and second-step state (Figures 4A and 4B), with different trial outcomes being most strongly differentiated in PC4 and PC5 (Figure 4C). Prior to the choice, trajectories diverged along an axis capturing choice selectivity (PC2). Following the choice, trajectories for different second-step states diverged first along one axis (PC3), then along a second axis (PC1), confirming that two orthogonal representations of second-step state occur in a sequence spanning the time period from choice through trial outcome.
