Figure 3
Single unit correlates of CCEPs. (a) Time histogram of CCEP-related firing activity, averaged across stimulation trials. The firing rate of clustered cortical neurons (n = 26, Pt1) shows significant and sequential changes after electrical stimulation. While in the time-window of P1-N1 components (0–50 ms) and during P3 (205–500 ms) there is a statistically significant increase in cell firing rate, during P2-N2 components (55–200 ms) the neuronal firing decreases significantly compared to the SUA measured both in pre- and poststimulation intervals (− 250–(− 5 ms) and 500–1000 ms, respectively). Asterisks on error bar plots indicate statistically significant differences in firing rate between all CCEP intervals and also between each interval and pre-and poststim. baseline periods (Kruskal–Wallis ANOVA; χ2(4) = 151.8, p < 0.001. Mann–Whitney U post-hoc tests, p < 0.01). (b) Changes in firing rates of two individual neurons recorded from layer II. (c) The most prominent changes in cell firing rate relative to prestimulus window are seen in layer V during P1-N1, although there is a statistically significant change in SUA in all cortical layers (significant differences, with p < 0.001, are marked by lines above boxplots, one-way ANOVA with Bonferroni post-hoc tests, for details see “Results”). Boxplots represent median with interquartile range (IQR), whiskers mark the most extreme values within 1.5xIQR. Crosses mark outliers outside this range. (d) Overlay plots of LFP (orange), CSD (black), MUA (light blue) and SUA (dark blue) in Pt1, separated layer-by-layer (averaged across channels within the corresponding layer). Shaded areas represent the same time-windows as in case of (a). Note that negative CSD values represent sinks, while positive values mark sources.
