Fig. 2.

Diverse cortical areas show distributed and modular long-range correlations. (A) Correlations across spontaneous events reveal distributed and modular networks that extend across several millimeters in both sensory and association areas. Pixelwise correlations are shown for two different seed points (Top/Bottom), revealing the presence of multiple distributed modular networks within each cortical region. (B, Left) The strength of correlations declines with distance in all cortical areas, remaining statistically significant vs. surrogate controls (dashed lines, 1 per area) up to at least 2 mm, the limits of our imaging window. (Right) The strength of long-range correlations (1.8 to 2.2 mm away from seed point) is similar across areas. Dots show individual animals, horizontal bar indicates mean across animals. Open squares show mean ± SEM for surrogate controls. (C) Spontaneous activity is moderately low dimensional in all cortical areas. Variance explained by principal components (Left) and participation ratio of spontaneous activity (Right) are similar across areas. Significant post hoc pairwise comparisons indicated by horizontal lines. Error bars ± SEM.