Brain wiring

It has been estimated that there is about a hundred times more cortical tissue devoted to the tips of the fingers than to a similar sized area of tissue in the abdomen. This increased brain space is thought to underlie the heightened perceptual abilities associated with these areas. But how do nerve fibres from certain sensory surfaces capture more cortical space to begin with? In April Nature Neuroscience, a study of the development of sensory appendages in the star-nosed mole shows that it might be a question of timing (Nat Neurosci 2001, 4:353-354).

Star-nosed moles have 11 sensory appendages surrounding each nostril. Although outwardly similar, one of these appendages — called the tactile fovea — is much more sensitive than the others. By studying the development of mole embryos Kenneth Catania of Vanderbilt University, found that the appendage destined to become the fovea has a distinct...