Figure 4.
Separation of time and f1 variance using an additional coordinate transformation. A, The time-dependent variance (blue) and f1-dependent variance (red) for the different dimensions of the new coordinate system. The first three panels show the results for three different monkeys, the last panel the results for monkey RR013 when the delay period was doubled to 6 s. In all monkeys, there is a natural separation into two subspaces. The first subspace (dimensions 1–3) captures almost all of the time-dependent variance (>96.3%), the second subspace (dimensions 4–6) almost all of the f1-dependent variance (>99.8%). B, Data projected onto the six axes of the new coordinate system for monkey RR013 (N = 842 cells). The numbers give the percentage of the overall variance captured by each component, similar to Figure 3D. C, D, Coordinate systems found using the same analysis for two other monkeys. These results are based on N = 161 cells (monkey RR014) and N = 361 neurons (monkey RR015), respectively. E, Monkey RR013 with a 6 s delay period (N = 123 neurons). The delay period activity is approximately rescaled by a factor 1/2. B–E, Scaling of the y-axis is normalized with respect to the first panel in each row.