Figure 1: Coupling of the variability of simultaneous recordings across V1’s local neuronal populations in urethane-anesthetized rats during spontaneous activity.

(a) CV within 10 s long independent blocks in which each dot represents one block throughout 2 h of recordings; each trace represents one local neuronal population (spot), one color per spot, gray continuous line represents the average curve. Triangles (red/blue) indicate the beginning of the time period used to sample inactive/active periods, respectively, in (b); arrows highlight time periods of reduced coupling. Dashed arrows represent 3 out of 6 spots that have higher variability than the other 3 spots; continuous arrow represents 1 out of 6 spots. (b) (top) Pearson’s correlation coefficient between the CVs as a function of the distance between spots; throughout the whole experiment, the red line indicates the median of the corresponding group; all p-values ≪ 0.001. Dashed line represents the same measure for Poisson-equivalent spike data with p-values ≫ 0.05 when compared to zero (except between spots 4 and 5). (bottom) Traces of action potentials of a spike train across the geometry used for recording channels in each cortical spot. (c) Samples of 4 s long recordings when inactive/active (left/right): (top) traces of raw data simultaneously recorded from six different shanks, one per spot approximately 200 μm apart, each one composed of 10 channels and colored according to the color code found in (a); (middle) corresponding raster plots for spikes found in each spot, one row per unit (n = 235), using the same color code found in (a), where MUA (n = 145)/SUA (n = 90) are surrounded by white/gray backgrounds, respectively; (bottom) corresponding population firing rate convolved with a Gaussian kernel, sigma = 100 ms, colored according the color code found in the raster plot, gray dashed line represents the mean population firing rate and vertical bars represent 1.5 spike/s/unit. (d,e) Spiking correlation for high/low levels of variability: (left) histogram and (right) correlation matrix with colormap in [−0.3;0.3]. (f) Scatter plot of mean CV versus mean spiking correlation in independent 300 s long periods.