Blind rats learned to navigate mazes just as well as those that could see, after scientists strapped a simple geomagnetic compass – the kind that’s found in your smartphone – fitted with electrodes directly onto their brains. Though they’re not naturally equipped to sense magnetic fields, the rats’ brains demonstrated tremendous plasticity and effectively incorporated a new sense! We can only presume this is possible in the case of humans as well, so the team from Japan which made the study believes blind people could incorporate a similar device – minus the brain hack. There are other alternatives after all, like say an iPhone app that acoustically alerts the blind person which way to turn or a sensor directly fitted into a walking cane.

An illustration of a rat wearing the geomagnetic device (credit: Norimoto and Ikegaya)

Yuji Ikegaya and Hiroaki Norimoto, both  of the University of Tokyo, wanted to see if blind rats could have their ability to navigate the world restored, but not by making them see. Instead, one a more fundamental level, they sought to restore their allocentric sense – the sense that allows animals to recognize their position relative to the environment. So, instead of eyes, why not graft rats with a geomagnetic compass. The device was connected with  two tungsten microelectrodes for stimulating the visual cortex of the brain. The lightweight package could be turned on or off remotely and included rechargeable batteries. Once attached to the brain, the sensors would read the direction of the rat’s head and would send pulses relaying information that told the rat which direction he was facing – north or south, for instance.

Geomagnetic sensor system, with connection to the primary visual cortex (adapted) (credit: Hiroaki Norimoto and Yuji Ikegaya/Current Biology)

The rats were then trained to find food in a T-shaped maze, then on with more complex shapes. After tens of trials, the rats with the geomagnetic sensors perform indistinguishably from the rats that could see, as reported in  Current Biology.

“We were surprised that rats can comprehend a new sense that had never been experienced or ‘explained by anybody’ and can learn to use it in behavioral tasks within only two to three days,” Ikegaya says.

“We 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.”

The world is a far richer place than we can imagine with our puny five senses. Imagine sensors that could be fitted to your brain to effectively sense infrared light, or ultrasound. Sixth sense? How about 20th sense? These is definitely some food for thought for any biohacker.

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