Some animals--such as pigeons--come with built-in compasses. Others, it seems, can be retrofitted. Researchers in Japan have managed to wire digital compasses, like the one in your smartphone, to the brains of blind rats. The rats learned to use the compass to find treats in a maze nearly as well as rats who could see.

Vision is really important to cultivating a sense of where your body is within the surrounding environment. Without it, blind people can have a tough time learning their way around a new space. Neuroscientist Yuji Ikegaya and pharmacologist Hiroaki Norimoto wanted to know if a geomagnetic signal could fill in for lost sight. So they sutured shut the eyes of 11 rats, and used microelectrodes to plug tiny digital compasses into their brains' visual cortices. The electrodes sent electrical pulses to the rats' neurons when their heads pointed north and south. Then the scientists set the bionic rats loose in a maze.