Blind rats navigate maze using implanted compass

The attached hardware allowed the blind rats to regain spatial awareness (Image: Norimoto/Ikegaya)

Researchers at the University of Tokyo have successfully used geomagnetic compasses to help blind rats navigate with a similar level of success to their fully-sighted counterparts. The team believes that the technology may be useful in helping blind people move around more freely.

To compensate for the test animals' lack of sight, the team attached a geomagnetic compass (similar to what you might find in a smartphone) to the blind rats, combining it with a pair of tungsten microelectrodes for stimulating the visual cortex of the brain. The device automatically detects the position of the rats' heads, generating electrical stimulation pulses to indicate the direction that the animal is facing – such as north or south, for instance.

The hardware itself is lightweight, includes a rechargeable battery, and is designed to allow the researchers to adjust the intensity of the brain stimulation. The device isn't designed to directly replace the rats' natural senses, but instead substitutes them with a new sensory input, thereby restoring their allocentric sense – an awareness of the position of their own bodies within the environment.

To test the effectiveness of the method, the rats were required to move through a maze in search of food pellets. The test was repeated tens of times, with the rats taking two to three days to learn to use the geomagnetic information to reach their goals. Overall, the blind rats performed similarly to their normally-sighted counterparts, using similar navigation strategies despite their impairment.

"The most remarkable point of this paper is to show the potential, or the latent ability, of the brain," said the University of Tokyo's Yuji Ikegaya. "That is, 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 team believes that the method indicates that it may be possible to augment our natural senses through artificial sensors. It also believes that the technology could be adapted in the short term, integrating geomagnetic sensors into canes, helping blind people move around more freely.

The study was published in the journal Current Biology on April 2.

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