Figure 7.

Spikes contributing most to co-firing also contributed most to HGA. a, An illustration demonstrating the calculation of mean CE HGA triggered by non-CE spikes. For all spikes on a given electrode, we averaged the corresponding CE HGA segments from −50 to 70 ms relative to the spike times to obtain the spike-triggered HGA for that electrode. b, Spike-triggered averaged HGA of the CE (two examples shown) showed a consistent activity pattern when aligned to the spike times of other electrodes. It peaked about 12.5 ms after spike time. c, An example of spike-triggered average HGA on the CE (red square) of monkey C, CE 63, plotted on each electrode from which the spike time was used to align the HGA. Red vertical line represents the spike time; the gray dashed line represents 50 ms after the spike time. HGA traces are color-coded by the absolute values of the co-firing weights from Fig. 4d. d, K-means clustering results using 2 clusters on the STA HGA traces, color-coded by the absolute co-firing weights. Cluster with apparent peak: “With response”; without apparent peak: “No response”.) e, A comparison of the absolute co-firing weights of the two clusters (***p<0.005, two-sided Wilcoxon signed-rank test). b,d,e, Left: monkey C, CE 63; Right: monkey J, CE 52.