Figure 3

Correlated clusters and correlated unclustered response distributions. (a) First spike response distribution for two neurons (L5AI, L4I) over 50ms following cortical onset (1 outlier out of view). Point colours illustrate DBSCAN clustering (epsilon = 1.35; Methods). Green flat ellipse illustrates \(4\sigma\) confidence interval of Stage 1 cluster. Dark blue angled ellipse illustrates \(4\sigma\) confidence interval of Stage 2 cluster. Light blue ellipse illustrates \(4\sigma\) ellipse of all spike pairs under independence and normality assumption. (b) Illustration of detected cluster in first spike pair response distribution (left) and unclustered first spike pair response distribution (right). (c) Linear regression p-values for Stage 1 clusters (left) and unclustered response distributions (right). (d) Top: number of correlations \((p<0.005)\) detected for the clustered (Stage 2 clusters) and unclustered case. Intersection shows the number of response distributions from which a correlation was detected by the clustering algorithm and for the unclustered case. Bottom: linear regression r-values of correlated \((p<0.005)\) Stage 2 clusters (left) and unclustered response distributions (right). (e) Left: histogram of variance explained (\(r^2\)) by the spike time linear relationship of each Stage 2 cluster (dark blue) and the linear relationship of the unclustered response distributions from which Stage 2 clusters were extracted (grey). Right: histogram of change in linear regression p-values introduced by clustering for response distributions from which Stage 2 clusters were extracted. Particularly, histogram shows Stage 2 cluster linear regression p-values minus originating response distribution linear regression p-values. Clustering reduces p-values in most cases (dark blue). (f) Histogram showing for each Stage 2 cluster, the proportion of conjunctive (both neurons spike) trials contributing a sample to the cluster (grey) and the proportion of stimulus trials contributing a sample to the cluster (dark blue). (g) Histogram of \(r^2\)-values of linear multi-output spike pair prediction from trial index (grey) and linear correlation (dark blue, blue) for Stage 2 cluster spike times (left) and unclustered response distributions (right).