Researcher Rewires Rat Brains To Sense Infrared Spectrum and Promises Much More

 Neuroscience  

Neuroscientist Miguel Nicolelis, whose research into man-machine interfaces and neuroplasticity could one day allow people to communicate directly with electronic devices by thought alone recently unveiled how his team's work allowed rats to sense infrared light, says his work is building rapidly and they will soon also announce a proof-of-concept of a brain-to-brain interface.

The Independent has reported that the scientist who has given a “sixth sense” to laboratory animals by allowing them to sense invisible infrared light has promised an even bigger revolution in the research field he has pioneered.

Miguel Nicolelis, the Brazilian neuroscientist working at Duke University in the United States, said that he has created a way of allowing animals to communicate with each other through artificial aids connected directly to their brains.

Nicolelis' research recently published in the journal Nature Communications showed that, although the touch region of the brain adapted to allow the rats to process the infrared signals, the ability to sense touch was not impaired. According to Nicolelis, using the touch cortex for light detection did not reduce the animal's ability to process touch signals.

"When we recorded signals from the touch cortex of these animals, we found that although the cells had begun responding to infrared light, they continued to respond to whisker touch. It was almost like the cortex was dividing itself evenly so that the neurons could process both types of information."

This research into the “man-machine interface” could one day allow people to communicate directly with electronic devices by thought alone. It could allow paralysed people to control artificial limbs or give blind or deaf people the possibility of seeing or hearing with the help of brain implants.

Professor Nicolelis told the Independent that he has now taken the research into a different realm by creating what he has called the “brain-to-brain inferface”. He said he could not provide further details because the work is due to be published later this month in a peer-reviewed journal under a strict confidentiality agreement.

In the study with rats, the animals were able to sense infra-red light effectively through the region of the brain connected to their whiskers. They used the light to locate water in a totally dark chamber.  According to Nicolelis, this was the first time that animals have been given a “sixth sense” using electronic devices connected directly to their brain.

“Our rats learn to touch invisible light. They are not seeing infrared light, but they are learning a concept that is similar to synesthesia [when one sense is detected by a different kind of sensory organ],” Nicolelis said.

“They learned to touch invisible light that is delivered by stimulating the touch cortex [of the brain]. In 30 days these animals acquired this pseudo-touch and we learned that they could use this to control other devices,” he told the American Association for the Advancement of Science in Boston.

“It was a big surprise because we bypassed the skin, we didn’t use the skin to deliver this signal...the animal is feeling light, not seeing light. It’s very interesting,” he said.

“We have extended this concept to what we have called a brain-to-brain interface...It’s an interface that no-one has dreamed could be done,” he added.

Although the researchers used infra-red light, Professor Nicolelis said that any physical energy, such as ultrasound, radio-waves or magnetic fields could be used as a new kind of sense.

It raised the prospect in the future of augmenting the human senses with brain implants that could detect things that are currently undetectable by the body, such as ultrasound, he said.

The rats in the experiment initially tried to rub their whiskers when they detected infra-red light. This was because a miniature light detector fitted to their heads was sending electrical impulses directly to the touch-sensitive region of the brain connected to whisker movements.

However, within the space of a few weeks they had learnt through training to distinguish this extra, artificial sense from real stimulation of their whiskers and use it to find water in a completely dark chamber, Professor Nicolelis said.

“It’s like driving a car or riding a bike. My suspicion is that these animals are feeling touch, its different from regular touch in that they are projecting the feeling of touch, not from their body, but to the external world,” he said.

“We have a monkey now that learned the same task and I was surprised at how quick he was. Now we are equipping our rats with a 360-degree view of the environment so that they can see infrared anywhere, up and down,” he added.

To ensure that the animals were really using the infrared detector and not their eyes to sense the infrared light, the researchers conducted trials in which the light switched on, but the detector sent no signal to the brain. In these trials, the rats did not react to the infrared light.

This finding of neuroplasticity is in contrast with the "optogenetic" approach to brain stimulation, which holds that a particular neuronal cell type should be stimulated to generate a desired neurological function. Rather, said Nicolelis, the experiments demonstrate that a broad electrical stimulation, which recruits many distinct cell types, can drive a cortical region to adapt to a new source of sensory input.

A major technical achievement that could enable the creation of a variety of neuroprosthetic devices was the laboratory's ability, announced last December, to record brain signals from almost 2,000 brain cells at once, an unprecedented number said Nicolelis.

Ultimately, the researchers hope to record the electrical activity produced simultaneously by 10,000 cortical neurons. Such massive brain recordings will enable more precise control of motor neuroprostheses—such as those being developed by the Walk Again Project  to restore motor control to paralyzed people, Nicolelis said.



SOURCE  The Independent

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