Is this the bionic man

Is this the bionic man


“Gentlemen, we can rebuild that. We have the technology,” declared the narrator at the beginning of the 1970s television series The Six Million Dollar Man. The program showed scientists reconstructing the broken body of accident victim Steve Austin with bionic implants that he could control with his mind. At the time, it was purely fiction, but two papers in this week’s Nature show that the direct interface of the human brain with a computer or robot is no longer limited to imagination.

Both papers report the development of electronic brain implants, called neuroprostheses, that can translate intent to move into a robotic device or the actual movement of a cursor on a computer screen. The hope is to give paralyzed patients a greater ability to interact with their environment and, perhaps, eventually, to bypass the damaged spinal cord and restore motion to lifeless limbs.

The papers represent the culmination of decades of investigation by several research groups into the computing, engineering and neurobiology of animals and humans. Yet they represent a technology that is still in its infancy: much remains to be done to make such neuroprostheses a clinical reality.

On page 164, researchers led by John Donoghue of Brown University in Rhode Island describe how they helped a 25-year-old patient who had a broken spinal cord.

They implanted an array of electrodes in the area of ​​his brain that controls movement, the motor cortex, and connected them to a computer interface. Even though his motor cortex was deprived of its normal interaction with the rest of his nervous system for three years, the patient was able to use the system to control the computer cursor, allowing him to open e-mail, control the television, etc. Helped to move and move. Objects using a robotic arm.

rapid progress

Donoghue’s team isn’t the first to experiment with this kind of implant. However, previous attempts have only been successful in getting patients to move the cursor horizontally. Other less-invasive techniques, which use scalp electrodes to pick up on brain activity, have taken months of training to adapt to the use. And techniques that rely on eye movements have the disadvantage that they require the full attention of the patient to operate. In Donoghue’s experiment, the patient adapted to the system within minutes, and was able to converse while using it.

But this type of neuroprosthetic system can be slow to use. So a group led by Krishna Shenoy of Stanford University, working with paralyzed monkeys, has established a technique for speeding up the interface of brain and machine (see page 195).

The progress that has been made is remarkable, but there are still many obstacles to be overcome. Current prostheses require the patient to be strapped to a heavy cart of equipment, and it requires constant fine-tuning by a team of technicians. The prototype implant has wires that penetrate the scalp and skin, but there is a risk of infection. Wireless signal transmission will address that particular issue at some level.

For reasons unknown, a more difficult problem may be the observed trend for the ability of microelectrode recordings from neurons over time. Individual responses to transplant also varied rapidly: a second patient in Donoghue’s experiment was unable to achieve the same control as the first.

And there are issues to come forward: If scientists were to be successful in restoring organ function, they would have to work out how the body tells the brain where in space its organs are located, a tiny mechanism called proprioception. through understanding (see page 125).

One indication of how far the science of neuroprosthetics has come is that most of these difficulties are now engineering challenges rather than problems of theory. In appreciating this valuable work, it is worth noting that it was made possible by two of the forte noirs of modern biology: commercial interest and animal research.

Donoghue’s team was supported by CyberKinetics Neurotechnology Systems – a private company in Massachusetts – of which Donoghue is the founder, director and chief scientific officer. Such heartfelt participation by commercial interests, at least in this area of ​​neuroscience, is unusual.

The experience of other scientific disciplines suggests that this route will pose new challenges, particularly in the free and open dissemination of data (see Nature 442, 1; 2006). However, these issues can be addressed, and they should not stop companies like CyberKinetics from taking this knowledge from the lab to the clinic.

Both papers also have much to do with primate research, including curiosity-driven research, which has been most strongly condemned by the animal-rights movement. Although some work can be done in rats, the best model of the human motor cortex is that of a monkey, the rhesus macaque.

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