[Animal Modeling]-Can you "see" without eyes? Scientists "inject" information into monkey brains
When you drive through an intersection and see a red light, you will (or should you) apply the brakes. You can do this thanks to a series of reactions in your brain.
Your eyes send signals to the visual center at the back of the brain. The processed signal will follow a pathway to an area called the premotor cortex, where the brain arranges movement.
Now, imagine implanting a device in your brain that can bypass pathways and take shortcuts and directly "inject" information into the premotor cortex.
This may sound like a scene from The Matrix. But now two neuroscientists from the University of Rochester (University of Rochester) have managed to get information directly into the premotor cortex in the monkey’s brain. The journal Neuron published the results of the scientists' experiments.
Although this is only a preliminary study, only two monkeys were tested, but the researchers speculated that more in-depth research may be used to perform brain implant surgery for stroke patients.
“It may be possible to bypass the damaged area and deliver the stimulus signal to the premotor cortex,” said Kevin A. Mazurek, a co-author of the study. "This method can be used to connect areas of the brain that are no longer accessible."
To study the premotor cortex, Mazurek and his co-author Dr. Marc H. Schieber trained two rhesus monkeys to play a game.
The monkey has to sit in front of a control board, which has a button, a knob, a cylindrical handle and a T-shaped handle. Each handle is surrounded by LED lights. If the LED lights around the subject are on, the monkey needs to reach out to the subject to receive the reward-in this study, the reward is to spray cool water.
Every object needs to make certain actions. If the button is lit, the monkey needs to press the button. If the knob is illuminated, you need to turn the handle. If the T-shaped handle or cylindrical handle is illuminated, the monkey needs to pull the handle.
After the monkeys learned how to play, Mazurek and Sibel let them play a wired version. The scientists placed 16 electrodes in the anterior motor cortex of each monkey's brain.
Every time a circle of lights is on, the electrode will pass a short but weak current. The pattern of electric current changes according to the different objects that scientists want the monkey to control.
After a few rounds of monkey play, the lights around the handle will be dimmed. At first, the dimmed light will make the monkey make mistakes. But their performance will improve.
In the end, the lights will be completely extinguished, but the monkeys can still rely solely on the signals transmitted from the electrodes to the brain to select and manipulate the correct objects to obtain rewards. And it behaves as well as when there is light.
This means that the sensory area of the brain that processes environmental information can be completely bypassed. The brain can directly receive information through electrodes and react.
Neuroscientists have long known that applying electric current to certain parts of the brain can cause certain parts of the body to twitch involuntarily. But this is different from what the monkeys experience.
Mazurek and Siebel eliminated this possibility by minimizing the pulse time. Although the impact is only one-fifth of a second, the monkey is still able to complete the game brilliantly without lights. Such a short pulse is not enough to make the monkey react with a twitch.
"The stimulus must have caused some conscious perception," said Paul Cheney, a neuroscientist at the University of Kansas Medical Center, who was not involved in the new experiment.
But what are the perceptions? It's hard to say. "After all, you can't just ask the monkeys how they feel," Cheney said.
Shibel guessed that the monkeys "may be able to feel something on their skin. Or they can see something. Who knows what it is?"
What makes this discovery particularly interesting is that the signals sent to the monkey’s brain by the scientists have no potential connection with buttons, handles, handles or cylinders.
Once the monkeys start to grab the correct objects based on these signals, the researchers will assign them new tasks. Now, by matching different electrodes to different objects, the monkeys quickly learned the new rules.
“This is not part of the inherent motion preset by the brain, but a learning engine,” said Michael A. Graziano, a neuroscientist at Princeton University. He was not involved in this research.
Mazurek and Sibel only implanted a small electrode array into the monkey. Engineers are studying implantable arrays that may include up to 1,000 electrodes. Therefore, in the future, it may be possible to deliver much more complex information packets to the premotor cortex.
Xibel predicts that in the future, scientists may be able to use this advanced electrode to help people with brain damage. For example, some parts of the path from the sensory area to the area where the brain makes decisions and give instructions to the body may be damaged by a stroke.
Implanted electrodes can eavesdrop on neurons in healthy areas, such as the visual cortex, and then forward the information to the premotor cortex.
"When the computer says, ‘when you see a red light’, you can say, ‘oh, I know what that means—I should put my foot on the brake,’" Sibel said. "You get information from a healthy area of the brain and send it to the downstream area that gives instructions to the body."
动物造模
z-bo
2020-09-04
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