Figure 5. Single-trial step-delay responses to C₀ and regressions on ΔC₀.

A. Top row: Cluster-mean scalp map and cluster-IC equivalent dipole locations. Below: After normalization by time warping (as in Fig. 4), the single-trial ERPs were pooled across all ICs in the pMFC cluster and sorted by the normalized difference (ΔC₀) between C₀ and expected C₀ latencies to make an ERP-image plot (vertical smoothing, 30 trials). Cool colors (blue) indicate negative activation values, warm colors (yellow to red) positive activation values. Dashed black vertical lines represent cue tones (C₀ to C₂). The leftmost dashed black trace represents the latency at which cue C₀ was expected to occur. Solid black traces represent heel strike latencies for steps S₁ and S₂. In upper trials with relatively large ΔC₀ the negative (SDN) deflection near 250 ms is stronger. The bottom panel shows the cluster-mean ERP. B. The effects of ΔC₀ on SDN magnitude and on SOA_1,2 adaptation-step size. Scatterplots for two of the 15 pMFC cluster ICs (subject 6 - 41 trials and subject 13 - 54 trials) showing relationships between ΔC₀ (on the x-axis), and z-scored SDN magnitude (blue dots) as well as z-scored adaptation-step size SOA_1,2 (red dots). Asterisks indicate significance (p<0.05).