Paralysis can have tremendous negative consequences for a person’s quality of life. In the US alone, there are more than 200 thousand people living with chronic spinal cord injury, which is a cause of immense suffering to them and their families. The disease generates economic burden for society as well. Thus, there has been a lot of interest in using our knowledge of how movement is coded in the brain to allow patients to bypass nerve injuries and communicate directly with the environment. Moreover, when asked about their priorities in terms of regaining motor function the vast majority of patients rank regaining arm and hand function as most important.
It is thus encouraging to read in Nature today an update on how these efforts by scientists have allowed a paralyzed patient to reach for a cup, bring it to her lips, and drink from it.
As explained in a nice News and Views piece by Andrew Jackson that accompanies the article, this type of work builds on decades of previous research on the neural mechanisms that control arm movements (here, here and here) (blue on the Fig above), on the development of chronic multi-electrode arrays (orange), their recording properties in animals, and on feasibility studies of neural interfaces in monkeys (here, here, here and here) (green), which opened the way to clinical studies in humans (here and here) (purple).
The value of animal research should not be difficult to grasp. The knowledge that allows us to “read out” the planned movements of the patient from different brain regions in order to guide the movement of the robot is critical in the design of the system. And it is an indisputable fact that such knowledge has been (and continues to be) obtained by experiments in awake, behaving monkeys.
And for those that doubt the true motivation of scientists for doing their work, it is worth noting what Dr. Leigh Hochberg (one of the leading authors of the study) had to say about their results — “The smile on her face … was just a wonderful thing to see.” Do you want to see her smile too? Watch this:
Of course the BrainGate system used by Dr. Hochberg and Dr. John Donoghue – director of the Institute for Brain Science at Brown University – is not the only brain-machine interface system under development to restore function in paralysis. In 2008 we wrote about a similar brain implant developed by Dr. Andy Schwartz at the University of Pittsburgh which enabled monkeys to manipulate robotic hands with unprecedented dexterity. Last year we wrote about how Dr. Schwartz’s team had used a different technology known as electrocorticography to enable a paralysed man to manipulate a robotic arm, while Dr. Chet Moritz and colleagues at Wachington National Primate Research Centre, have coupled readings from individual nerve cells to a technology called functional electrical stimulation to restore control to temporarily paralysed muscles in monkeys, an approach that may eventually supersede the use of robotic arms in some patients. It will be fascinating to watch this technology progress into more widespread clinical use over the next decade, and thrilling to think that, impressive as it appears today, we have barely begun to tap the potential of brain-machine interface technology to change lives.