Correlation between spike activity and LFP

<p><b>A.</b> SOA-dependent spike modulation for the cell shown in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0144929#pone.0144929.g003" target="_blank">Fig 3</a>. The mean firing rates during the post-stimulus period of 50–150 ms of S2 are plotted as a function of SOA. Vertical dashed lines are the reference response levels evoked by S2 alone. <b>B.</b> Simultaneously recorded mean LFP traces in an arbitrary unit for corresponding SOAs for the cell shown in A. Traces are vertically shifted for visibility. <b>C.</b> Time course of mean correlation between spike and LFP modulation. The correlation coefficient between the SOA-dependent firing rate (as shown in A) and the instantaneous amplitude of LFP (as shown in B) was first calculated every 1 ms for each condition. Shown is the mean correlation coefficient time course averaged over all 517 stimulus conditions (11 SOAs X 47 S1-S2 sequences) from 31 cells including cases in which S1 was tested at more than one RF diameter away. The shading represents ±1 SE. Note a positive correlation immediately after S2 onset (arrow) and a subsequent negative correlation. <b>D, E.</b> Frequency histograms of the time from S2 onset (D) and the correlation coefficient (E) for the 1<sup>st</sup> (upper) and 2<sup>nd</sup> (lower) peaks in the time course of correlation. Dashed vertical lines indicate distribution means. For the 1<sup>st</sup> peak correlation, the mean location was 45.25 ±36.0 ms and the mean correlation coefficient was 0.32 ±0.24. For the 2<sup>nd</sup> peak, the mean location was 119.32 ±38.3 ms, and the mean correlation coefficient was -0.42 ±0.33. Black bars indicate significant cases, as determined with a bootstrap statistical test (p<0.05).</p