Comprehensive computational modelling of the development of mammalian cortical connectivity underlying an architectonic type principle
Fig 9
Youden index for prediction of empirical connection existence from simulation data.
A classifier was trained to predict connection existence of a simulated network from the associated distance and absolute density difference. Youden index J for predicting existence of connections in two species (macaque, blue; cat, green) by this classifier is shown. Youden index J was determined at each classification threshold (see Methods); here, we show mean J across thresholds 0.750 to 0.975. Whether the Youden index was better than chance was assessed by a permutation test, where J was calculated for prediction from randomly permuted labels and a z-test was performed. A sign test was used to test whether the distribution of associated z-test p-values had a median value smaller than α = 0.05. The result of the sign test is indicated on top; black star: performance better than chance with median p < 0.05, red circle: performance not better than chance with median p > = 0.05. Box plots show distribution across 100 simulation instances per growth layout, indicating median (line), interquartile range (box), data range (whiskers) and outliers (crosses, outside of 2.7 standard deviations). See Table 4 for a summary. Abbreviations and background colours as in Table 1.