How feedback from cortex helps mammals make fine distinctions about odors

Everyday tasks we may regard as 'simple' -- for example, knowing the difference between the smell of an orange and a pickle -- are actually marvels of evolutionary development, the work of eons. A neuroscience team reports results of experiments that suggest how the mammalian brain distinguishes odors -- not just dissimilar ones but, perhaps more importantly, odors that are nearly identical, such as the scents of oranges and tangerines.