With the sheer number of images, can certain voxels light up as false-positives? You betcha. Is every voxel significant? Well, to answer that, Craig Bennett and his colleagues took a dead Atlantic Salmon, and placed it in an fMRI. The salmon was then shown a series of photographs depicting humans in various social situations. The (dead, remember?) fish was asked to determine which emotion each individual has been experiencing. They scanned the salmon’s (did I say it was dead?) brain, and collected the data. They also scanned the brain without showing the fish the pictures. The images were then checked for change between the brain doing picture recognition tasks, and the brain at rest, voxel by voxel. They found several active voxel clusters in the (yes, still dead) salmon’s brain.