Fig. 3.

Two-interval time decode. (A) The two-interval time-decode analysis for the vibrotactile-discrimination task for delay intervals of 3 and 6 s is shown for both the data and RNN model. The longer delay-period intervals used in this task reveal neural dynamics that evolve slowly, on a timescale of approximately half a second (see also Fig. 5B). Time can be decoded but with limited precision. (B) Two-interval time-decode matrices for the vibrotactile-discrimination task and trace-conditioning task are similar during the delay interval after stimulus offset, when truncating the vibrotactile dataset to match the 1,500-ms delay interval used in the trace-conditioning task. The similarities in these two datasets suggest the observations in the trace-conditioning task are compatible with a slowly varying dynamics, which have been truncated due to the shorter 1,500-ms delay interval used in this experiment (see also SI Appendix, Fig. S12). (C) Two-interval time-decode matrices for the interval-reproduction task (41), duration-discrimination task (42), and stabilized random RNN (17) reveal that time is encoded with higher precision in tasks that explicitly require tracking time. Times are aligned to the ready cue for the interval-reproduction task, S1 onset for the duration-discrimination task, and stimulus offset for the stabilized random RNN. There are no external events during the 1,000-ms interval over which the two-interval time decode is shown, i.e., no external inputs or visual stimuli were changed during this 1,000-ms interval.