Fig 3. Correlations between ELL pyramidal cell activities are nearly identical across the ELL segments.

(A) Simultaneous extracellular recordings of baseline activity (i.e. in the absence of stimulation) from pairs of pyramidal cells were obtained in all three ELL segments. Recordings were performed using two metal-filled micropipettes inserted into the pyramidal-cell layer of the respective ELL map (mean recording duration: 105 s; range: 39–318 s). (B) Absolute spike-count correlation coefficient for LS (blue), CLS (magenta), and CMS (green) as a function of the time window t. Shown are mean (white lines), SEM (colored areas) and STD (gray shaded areas) correlation coefficients across the populations of pairs recorded in each segment (LS: N = 23; CLS: N = 108; CMS: N = 24). The correlation coefficients obtained for the three segments were similar and thus largely overlapped with one another. (at t = 100 ms: median LS: 0.14, range: 0.009–0.44; CLS: 0.16, 0.001–0.48; CMS: 0.22, 0.003–0.5). (C) Population-averaged absolute correlation coefficient for t = 100 ms (see vertical dotted line in B). At this time scale, the means of the distributions were not significantly different from one another (Kruskal-Wallis; df = 2; Chi² = 1.66; p = 0.44). Qualitatively similar results were obtained for other time windows (e.g.: t = 10 ms; Chi² = 1.64; p = 0.44; or t = 1 s; Chi² = 2.78; p = 0.25).