Interpretation of correlated neural variability from models of feed-forward and recurrent circuits
Fig 7
Scaling of covariances with average response, in experiments and models.
A, B: Distribution of parameters ρ and ρext (variability of network connections and stimulus input) estimated from all experiments. C: Histograms of cos(d,r(s)) from mean responses across stimuli, for a selection of populations recorded from in one animal. Filled histograms: experimental data. Solid lines: model results for 500 randomly generated stimuli and one network with random effective connections, parameters inferred from data. D: Population-averaged variances and covariances versus population-averaged response, for all stimuli (full circles) in one experiment and for corresponding feed-forward models (empty circles). Dashed lines represent linear fits. E: Scatter plot of ratio slope/intercept from linear fits in all experiments (excluding four outliers with very low intercept) versus corresponding values in the feed-forward model. Orange circle indicates population used in panel D. F: The ratio intercept/slope is consistent for covariances and variances, across experiments (dots). G: Distribution of estimated slopes for average variances. H: Distribution of estimated 〈Vext〉 (intercept/slope from fits to variances) compared to distribution of average and minimum firing rate across experiments.