Fig. 7. Initial conditions and inputs determine speed of dynamics and ultimately choice and RT behavior.
a First three PCs (PC1,2,3) of firing rates aligned to checkerboard onset (red dots) and conditioned on stimulus coherence and choice. We observed strong poststimulus separation as a function of choice and coherence, but no observable prestimulus (-400 ms to 0 ms) separation. Color-matched diamonds and squares, indicate 225 ms post-checkerboard onset and 20 ms time steps respectively. b Choice-selectivity signal measured as the 6-dimensional Euclidean distance (E. distance) between left and right reaches as a function of stimulus coherence. c State space trajectories of the 1st, 2nd and 4th PCs of PCAs conditioned on RT bins and action choice within three stimulus coherences (90%, 31%, & 4%). d Choice-selectivity signal for each of the three coherences shown in c as a function of RT bin. e Average choice-selectivity (CS) signal in the 125 to 375 ms after checkerboard onset as a function of the initial condition (IC) within each coherence (Coh.). Easier coherences lead to higher choice-selectivity signals regardless of initial condition, but the magnitude of this signal depends on the initial condition as well as sensory evidence. f Latency of the choice-selectivity signal as a function of the initial condition (IC) and for each stimulus coherence (Coh.). As expected from (d), the latency is largely flat for the easier coherences and faster RT bins (regardless of coherence), but slower for the harder coherences. The bend down in e and the bend up in (f/g) for the fastest RT bin (300-400 ms, violet) is likely an artifact of fewer trials in this bin. g Slope of the choice-selectivity signal (m term in eq. 21) as a function of the initial condition (IC) and coherence (Coh.). Slopes strongly depend on initial condition but only weakly on coherence. h Same as (d), but for non-overlapping bins. Notice similarity between (h) and (d). Bend down in (h) emerges due to truncation of firing rates at movement onset when averaging. i–k Same as (e)–(g) but for non-overlapping bins. Again the choice selectivity depends on both initial condition (IC) and coherence (Coh.). Cue - Checkerboard onset. Source data are provided as a Source Data file.