Brain gene expression was determined using Affymetrix MOE430 v2 arrays from 4–5 mice at each generation. Following normalization and filtering for expression above background, differences in expression at each generation, that were maintained throughout selection (until generation 13), were determined using a moderated t-test (Panel A). Similarly, probesets that displayed reduced variance of expression, compared to generation 0 (HS mice), and that maintained that reduced variance throughout selection, were determined (Panels B and C). The cumulative number of probesets that displayed these characteristics at each generation of selection is indicated. Colors indicate the generation of which differential expression or reduced variance began.