On April 10 Netflix will begin streaming Daredevil, their addition to the Marvel cinematic universe that’s already home to big screen heroes like Thor and Captain America. Lawyer-by-day/vigilante-hero-by night Matt Murdock, Daredevil’s titular protagonist, compensates for his chemically induced blindness with a superhuman sensory system, which not only boosts his remaining four senses, but also affords him a form of human echolocation; He can navigate his way through the world around him, “seeing” without his eyes.
That, in effect, is what a group of blind laboratory rats are now able to do, thanks to the work of Hiroaki Norimoto and Yuji Ikegaya, researchers from the University of Tokyo. In their just-published paper, “Visual Cortical Prosthesis with a Geomagnetic Compass Restores Spatial Navigation in Blind Rats,” Norimoto and Ikegaya describe applying “geomagnetic prosthetics” to a number of rats whose eyelids had been sealed shut in order to feed spatial information directly into rodents’ brains. They have, in other words, given sightless rats, if not the ability “see,” at least the means to behave as if they can.
Per the paper’s synopsis:
Head-mountable microstimulators coupled with a digital geomagnetic compass were bilaterally implanted in the primary visual cortex of adult rats whose eyelids had been sutured. These “blind” rats were trained to seek food pellets in a T-shaped maze or a more complicated maze. Within tens of trials, they learned to manage the geomagnetic information source to solve the mazes. Their performance levels and navigation strategies were similar to those of normal sighted, intact rats. Thus, blind rats can recognize self-location through extrinsically provided stereotactic cues.
The key here is the body’s natural allocentric sense, which regulates how people move spatially within their environment. Those with visual impairments have difficulty navigating not only because they can’t see obstacles in front of them, but because they have what the researchers call a “deficit of absolute direction perception.” By bypassing the rats’ eyes, and externally triggering the visual cortex directly to correspond with north/south alignment, the researchers effectively boosted the rodents’ allocentric sense to compensate for the lack of that directional perception. The result is the subjects’ ability to navigate as if they were “normal sighted, intact rats.”
As Spectrum points out, there’s both practical applications for this sort of research—equipping walking sticks with an iteration of the technology used could help further improve mobility for the visually impared—and a larger lesson to be learned. Writes Spectrum’s Charles Q. Choi:
[T]hese findings support the idea that brains are flexible enough to adapt to completely new senses. This suggests that people could one day successfully expand their senses with artificial sensors that detect magnetic fields, ultraviolet rays, ultrasound waves, and more.
So while Daredevil may be hitting Netflix in just a few days, science’s ability to augment our senses to superhuman levels may not be all that far behind.
