Rats detect infrared light with sense of “touch”
DURHAM, N.C. – Although they can’t see it, rats can now “touch” infrared light using a detector wired to electrodes implanted in a specific area of their brains. The discovery could have significant implications for the disabled.
Brain-controlled prosthetics currently do not provide patients with a sense of an object’s texture, said Duke University neurobiologist Miguel Nicolelis. His goal is to provide quadriplegics not only the ability to move their limbs again, but also to sense the textures of objects placed in their hands or to experience the nuances of the terrain under their feet.
Rats can’t see infrared light, but they can now “touch” it using a detector wired to a part of their brain that processes information related to the sense of touch. The Duke University experiment could have significant implications for the disabled.
Previous lab studies by his team gave monkeys the ability to control limbs, both real and virtual, using only their minds. Their electrical brain activity guided the virtual hands of an avatar to touch virtual objects and recognize their simulated textures.
In their latest study, Nicolelis and colleagues demonstrated that the rats’ cortexes respond both to the stimulated sense of touch created by the infrared light sensors and to whisker touch, as if the cortex were dividing itself evenly so that the brain cells could process both types of information. Their findings were published in Nature Communications (doi: 10.1038/ncomms2497).
This counters current optogenetic approaches to brain stimulation, which suggest that particular neuronal cell types should be stimulated to generate a desired function. Instead, stimulating a range of cell types might help a cortical region adapt to new sensor sources, Nicolelis said.
The firing patterns of nearly 2000 individual, interconnected neurons in monkeys were documented recently. Such recordings are important for improving the accuracy and performance of neuroprosthetic devices, he said.
The brain-machine interface is part of an international effort called the Walk Again Project, which is aimed at building a whole-body exoskeleton that could help paralyzed people regain motor and sensory abilities using brain activity to control the apparatus. The exoskeleton will be demonstrated in June 2014 at the FIFA Soccer World Cup opening ceremony.
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