A team of researchers has reported that by hooking a microstimulator and geomagnetic compass to the brain, blind rats act like they can see.
Researchers found that by attaching these devices, the animals can spontaneously learn to use new information about their location to navigate through a maze nearly as well as normally sighted rats, suggesting that a similar kind of neuroprosthesis might help blind people walk freely through the world.
Yuji Ikegaya of the University of Tokyo said that they demonstrated that the mammalian brain is flexible even in adulthood enough to adaptively incorporate a novel, never-experienced, non-inherent modality into the pre-existing information sources. In other words, he says, the brains of the animals, they studied, were ready and willing to fill in the world drawn by the five senses with a new sensory input.
The head-mountable geomagnetic sensor device the researchers devised allowed them to connect a digital compass (the kind you'd find in any smart phone) to two tungsten microelectrodes for stimulating the visual cortex of the brain. The very lightweight device also allowed the researchers to turn the brain stimulation up or down and included a rechargeable battery.
Once attached, the sensor automatically detected the animal's head direction and generated electrical stimulation pulses indicating which direction they were facing north or south, for instance.
The blind rats were then trained to seek food pellets in a T-shaped or a more complicated maze. Within tens of trials, the researchers report, the animals learned to use the geomagnetic information to solve the mazes. In fact, their performance levels and navigation strategies were similar to those of normally sighted rats. The animals' allocentric sense was restored.
The findings suggest one very simple application: to attach geomagnetic sensors to the canes used by some blind people to get around. More broadly, the researchers expect, based on the findings, that humans could expand their senses through artificial sensors that detect geomagnetic input, ultraviolet radiation, ultrasound waves, and more. Our brains, it appears, are capable of much more than our limited senses allow.
The study appears in the Cell Press journal Current Biology.