Cover legend: High-resolution optical imaging of intrinsic metabolic brain activity reveals spatial organization of responses to tone scales in five auditory cortical areas of the rat. The rainbow progression from blue to green indicates sensitivity spanning low to high notes in a tone scale. Spike rate responses to binaural sound level cues in these same regions are organized into spatial meta-gradients and superfields that fall within and outside the field boundaries defined by tone response gradients. For reference, the large vessel on the left in the surface blood vessel overlay is the ascending branch of the inferior cerebral vein. For more information, see the article by Higgins et al. in this issue (pages 14522–14532).