Fig. 5: Task-discriminative relevance estimates for the AAL atlas for the network occlusion sensitivity analysis (NOSA) and gradient backpropagation (GBP) approaches for the age and gender-based classification task.
a Aggregate relevance of each brain region was estimated for each independent (n = 20) cross-validation repetition for the largest training sample size runs (ntrain = 10,000, nvalidation = 1157 and ntest = 1157 subjects). Thus, for both saliency methods, each boxplot outlines the variation in the mean relevance percentages for each corresponding brain region across the independent (n = 20) cross-validation runs of the classification task. In these boxplots, the box shows the inter quartile range (IQR between Q1 and Q3) of the data set, the central mark (horizontal line) shows the median and the whiskers correspond to the rest of the distribution based on the IQR [Q1–1.5*IQR, Q3+1.5*IQR]. Beyond the whiskers, data are considered outliers and represented by red circles. These estimates generally spanned a narrow range (except for few outliers runs for some brain regions), and a comparison of these standard approaches confirmed consistency in the trends for most of the brain regions. Note, the AAL atlas brain regions are sorted from higher relevance to lower relevance for the NOSA approach for this illustration. b The NOSA and GBP saliency mapping methods showed a high correlation value (r) of 0.92 in the mean relevance estimates for each brain region (listed on the y axis of a), thus confirming the consistency in the relevance obtained from the learned DL representations. The dotted line represents the least squares fit for this relationship. Source data are provided as a Source Data file.
