When you drive toward an intersection, the sight of the light turning red will (or should) make you step on the brake. This action happens thanks to a chain of events inside your head.
Your eyes relay signals to the visual centers in the back of your brain. After those signals get processed, they travel along a pathway to another region, the premotor cortex, where the brain plans movements.
Now, imagine that you had a device implanted in your brain that could shortcut the pathway and “inject” information straight into your premotor cortex.
That may sound like an outtake from “The Matrix.” But now two neuroscientists at the University of Rochester say they have managed to introduce information directly into the premotor cortex of monkeys. The researchers published the results of the experiment on Thursday in the journal Neuron.
这听起来或许像是《黑客帝国》(The Matrix)中的一幕。但现在已有两名来自罗切斯特大学(University of Rochester)的神经学家在猴子的大脑中做到了使信息直接进入前运动皮层。周四，《神经元》(Neuron)期刊发表了科学家的实验结果。
Although the research is preliminary, carried out in just two monkeys, the researchers speculated that further research might lead to brain implants for people with strokes.
“You could potentially bypass the damaged areas and deliver stimulation to the premotor cortex,” said Kevin A. Mazurek, a co-author of the study. “That could be a way to bridge parts of the brain that can no longer communicate.”
“也许可以绕开受损区域，将刺激信号输送至前运动皮层，”该研究的一位共同作者凯文.A.马祖雷克(Kevin A. Mazurek)说。“用这个办法可以连通大脑中已经无法联系上的区域。”
In order to study the premotor cortex, Dr. Mazurek and his co-author, Dr. Marc H. Schieber, trained two rhesus monkeys to play a game.
为了研究前运动皮层，马祖雷克和他的共同作者马克.H.希贝尔博士(Dr. Marc H. Schieber)训练两只恒河猴来玩一种游戏。
The monkeys sat in front of a panel equipped with a button, a sphere-shaped knob, a cylindrical knob, and a T-shaped handle. Each object was ringed by LED lights. If the lights around an object switched on, the monkeys had to reach out their hand to it to get a reward — in this case, a refreshing squirt of water.
Each object required a particular action. If the button glowed, the monkeys had to push it. If the sphere glowed, they had to turn it. If the T-shaped handle or cylinder lit up, they had to pull it.
After the monkeys learned how to play the game, Dr. Mazurek and Dr. Schieber had them play a wired version. The scientists placed 16 electrodes in each monkey’s brain, in the premotor cortex.
Each time a ring of lights switched on, the electrodes transmitted a short, faint burst of electricity. The patterns varied according to which object the researchers wanted the monkeys to manipulate.
As the monkeys played more rounds of the game, the rings of light dimmed. At first, the dimming caused the monkeys to make mistakes. But then their performance improved.
Eventually the lights went out completely, yet the monkeys were able to use only the signals from the electrodes in their brains to pick the right object and manipulate it for the reward. And they did just as well as with the lights.
This hints that the sensory regions of the brain, which process information from the environment, can be bypassed altogether. The brain can devise a response by receiving information directly, via electrodes.
Neurologists have long known that applying electric current to certain parts of the brain can make people involuntarily jerk certain parts of their bodies. But this is not what the monkeys were experiencing.
Dr. Mazurek and Dr. Schieber were able to rule out this possibility by seeing how short they could make the pulses. With a jolt as brief as a fifth of a second, the monkeys could still master the game without lights. Such a pulse was too short to cause the monkeys to jerk about.
“The stimulation must be producing some conscious perception,” said Paul Cheney, a neurophysiologist at the University of Kansas Medical Center, who was not involved in the new study.
“刺激肯定是造成了一些有意识的感知，”堪萨斯大学医学中心(University of Kansas Medical Center)的神经学家保罗.切尼(Paul Cheney)说，他并未参与本次新实验。
But what exactly is that something? It’s hard to say. “After all, you can’t easily ask the monkey to tell you what they have experienced,” Dr. Cheney said.
Dr. Schieber speculated that the monkeys “might feel something on their skin. Or they might see something. Who knows what?”
What makes the finding particularly intriguing is that the signals the scientists delivered into the monkey brains had no underlying connection to the knob, the button, the handle or the cylinder.
Once the monkeys started using the signals to grab the right objects, the researchers shuffled them into new assignments. Now different electrodes fired for different objects — and the monkeys quickly learned the new rules.
“This is not a prewired part of the brain for built-in movements, but a learning engine,” said Michael A. Graziano, a neuroscientist at Princeton University who was not involved in the study.
“这并不是大脑预置的固有运动的一部分，而是一个学习引擎，”普林斯顿大学(Princeton University)的神经学家迈克尔.A.格拉齐亚诺(Michael A. Graziano)说。他没有参与这项研究。
Dr. Mazurek and Dr. Schieber only implanted small arrays of electrodes into the monkeys. Engineers are working on implantable arrays that might include as many as 1,000 electrodes. So it may be possible one day to transmit far more complex packages of information into the premotor cortex.
Dr. Schieber speculated that someday scientists might be able to use such advanced electrodes to help people who suffer brain damage. Strokes, for instance, can destroy parts of the brain along the pathway from sensory regions to areas where the brain makes decisions and sends out commands to the body.
Implanted electrodes might eavesdrop on neurons in healthy regions, such as the visual cortex, and then forward information into the premotor cortex.
“When the computer says, ‘You’re seeing the red light,’ you could say, ‘Oh, I know what that means — I’m supposed to put my foot on the brake,’” said Dr. Schieber. “You take information from one good part of the brain and inject it into a downstream area that tells you what to do.”