Distinct Subtypes of Somatostatin-Containing Neocortical Interneurons Revealed in Transgenic Mice

Multivariate analysis of electrophysiological parameters. A, Grouping of parameters according to their CV and their η². The nine numbered data points correspond, respectively, to the numbered parameters in B. The half-box (near the origin of axes) encloses parameters with η² < 0.1 and CV < 0.35. B, Density plots (computed with a Gaussian kernel) of the nine parameters with η² > 0.1, separated by transgenic line. Only the two extreme x-values are indicated for each plot. Parameters 1–3 are plotted in a logarithmic scale. C, Total-sample correlation matrix of parameters 1–9; the absolute values of the pairwise Pearson correlation coefficients are coded by color. D, Pooled within-group correlation matrix of the nine parameters. Note the separate clusters of passive (1–3) and active (4–9) parameters; parameters are correlated within, but not between, each cluster. E, Scatterplot of the electrophysiological parameters of the three neuronal subtypes in the principal component plane. Each principal component is a linear combination of the original 9 parameters; PC1 correlates strongly with active parameters, PC2 with passive parameters. X94 data points are separated into layer 4 and layer 5B cells. F, Scatterplot of the electrophysiological parameters of the three neuronal subsets in the canonical discriminant function plane. Each CDF is a linear combination of 11 electrophysiological parameters. X94 neurons are separated into layer 4 cells and layer 5B cells. The two intersecting lines separate the plane into three regions, with good segregation of the three groups into separate regions.