Geordi La Forge, the chief engineer of the USS Enterprise-D, could perceive a large swath of electromagnetic spectrum with his wraparound VISOR prosthetic. Now a few rats have received real-life prototypes of these Star Trek props.
Researchers in the lab of brain–machine interface ace Miguel Nicolelis at Duke University Medical Center have outfitted rodents with prosthetics that enable them to "see" and respond to otherwise invisible infrared light. The experiment points toward the prospect, for the moment still a futurist's overheated fantasy, of enhancing humans with a sixth or seventh sense or, perhaps, like a VISOR, an ability to detect a full-spectrum of electromagnetic emanations. It also suggests new paths for neuroscientists to explore the mixing of different sensory inputs and neural proceses to produce new forms of perception.
Reporting February 12 in the online journal Nature Communications, Nicolelis and colleagues recounted how they trained six rats on a standard lab task that taught them to stick their snouts in one of three holes in the side of a chamber when a light in one of the cavities switched on, an action rewarded with a sip of water. (Scientific American is part of Nature Publishing Group.) They then implanted microelectrodes in the rats’ primary sensory cortex, an area that processes sensations of touch. These electrical stimulators were subsequently connected to a forehead-mounted infrared detector. Once the animals were back in the test chamber, the experiment was repeated, with visible lights gradually being replaced by infrared ones in the three holes.
At first the rats appeared somewhat confused, poking the holes in the chamber at random, possibly because the “wrong” portion of the cortex (the part that normally process touch) was interpreting the electrical signals for visual cues. Gradually, their behavior changed and they began to respond more as they had to the visible-spectrum LEDs during training, a sign that their brains were adapting to seeing in the infrared. The same area of the cortex also continued to respond normally to whisker touches as well as the infrared signals. Take a look at this video made with an infrared camera:
"This is a very nice paper that clearly demonstrates the great potential of even the primary sensory cortex, even in a rat, to use completely new information when delivered to the cortex in electrical pulses," says Jon Kaas, a professor of cell and developmental biology at Vanderbilt University and an expert on sensory and motor system organization. "The authors correctly see that this method of delivery can be used to replace lost sensory inputs and to provide new sensory abilities."
The sixth-sense prosthetic could be used for shoring up the first five: If a tumor damages the visual cortex at the back of the brain, the primary sensory cortex on top—still thought by many neuroscientists to be inalterably hardwired for touch—might be commandeered to process incoming visual signals. The Duke researchers have begun to do similar experiments with howler monkeys.
The device can also explore possibilities for brain enhancement. The rats, Nicolelis says, seemed to be developing a new form of behavior. “The closest I can describe it is to say they were touching light because they don’t see the light,” he says. “They process this invisible light as a new form of touch. So they change the way they move their heads. They scan the environment with sweeps of the head looking for light and this is not a typical way that animals perceive light. They created an exploratory behavior as a consequence of being able to perceive a new signal.”
Future experiments will also assess the possibility of fully developed infrared vision—equipping the brain with the equivalent of night vision goggles that can detect all of the contrast and intensity of the infrared environment. On the to-do list as well are devices that enable the perception of other forms of energy alone or in VISOR-like combination—X rays, magnetic fields or radio waves. “It’s pretty interesting to try to understand whether there’s a limit, whether the brain is really capable of adapting to combine a huge number of [electromagnetic] energies and altering our perception of world,” Nicolelis says.
A "sixth sense" prosthetic is in line with other research from Nicolelis's laboratory that is looking at technologies that will not only correct cognitive defects, but also extend and elaborate on the brain's organic capabilities—the ability to mix sensory perceptions between two rat brains is one possibility (shades of the Vulcan mind meld!). There are also plans for a brain-controlled exoskeleton to allow a handicapped child make the first kick for the 2014 World Cup.
The sixth-sense device might be one small step toward developing and implementing the science of Star Trek. It still may be a while, though, before Nicolelis's extra-sense machine will let a rat shift between parallel universes, as the VISOR did for Lt. Worf in "Parallels," the 163rd episode of Star Trek: The Next Generation.