Image: LANA FINCH/Courtesy of the Proceedings of the National Academy of Sciences
Using microelectrodes to record neuronal activity in the rodents, Kenneth C. Catania and Michael S. Remple of Vanderbilt University determined that nearly one third of the naked mole-rat's so-called primary somatosensory cortex (the part of the brain related to touch) is devoted to sending and receiving information to and from those bizarre front teeth. The animal's forepaws, in contrast, are allotted only 10 percent of cortex space. (The image at the right shows the relative proportions of body parts as they are represented in the naked mole-rat's neocortex.) Furthermore, the team found, the mole-rat somatosensory cortex is significantly larger relative to the size of the entire neocortex than that of closely related lab rats.
Catania and Remple also report that the naked mole-rat's somatosensory cortex appears to have taken over all areas of the neocortex normally devoted to vision. For now, the payoff of devoting so much of the cortex to the teeth remains unclear, the authors note. But whatever the reason, these new results, they assert, "indicate that major cortical remodeling has occurred in naked mole-rats, paralleling the anatomical and behavioral specializations related to fossorial life."