Among neuroscientists, the term “brain-machine interfaces” has been hot for a while.
An emerging field, it describes efforts to use what’s known about how the brain processes and packages information in order to develop machines or devices that help people regain function after injury or disease.
Think: Your brain alone can control the cursor of a computer.
That’s not as sci-fi as it sounds. At Neuroscience 2010 in San Diego this week, at the annual meeting of the Society for Neuroscience, researchers reported on how brain-machine interfaces are allowing brain control of cursors, speeding the recovery of hand control in stroke patients, and offering hope for restoring sight after retinal damage.
In only 6 minutes, participants in one study learned how to move a screen cursor with their thoughts alone, said Anna Rose Childress, Ph.D., a researcher at the University of Pennsylvania School of Medicine.
Here’s how: The participants were inside a functional MRI scanner, which registers blood flow in regions of the brain that are active. Other research has suggested that when people are provided feedback about these brain signals, they can gain control over them.
As the participants lay in the scanner, computers learned to detect two brain patterns exhibited by the volunteers. In one, the participants were asked to think about hitting a tennis ball and in the other to imagine moving from one room to another.
Next, they repeated the thought patterns and moved a screen cursor linked to their brain activity.
”Each thought is linked with activity in a specific brain part,” Childress said. The tennis ball represented repetitive arm activity and the moving from room to room represented spatial navigation.
All 14 subjects, after the short training, were able to move the cursor with their thoughts.
In other research, a combination of brain stimulation and physical therapy speeded recovery of hand control in stroke patients, said Satoko Koganemaru, M.D., Ph.D., a researcher at Kyoto University in Japan.
”Stroke results in abnormally increased muscle tension plus the muscle weakness,” she said.
She administered transcranial magnetic stimulation, a noninvasive technique sometimes used to treat depression, to 9 stroke patients. It was applied over the side of the brain that was damaged by the stroke, in the area linked with motor control.
The patients also did ”motor practice,” contracting and releasing the muscles of their fingers and wrists.
The combination therapy continued twice a week for 6 weeks.
Koganemaru showed a video of one patient. “We found the patient could move the wrist and hand in a wider range,” she said. The patient had stronger grip as well, she said.
Three months later, the improvements were maintained. Why? “Through practice and brain stimulation, the brain adapts,” Koganemaru said, “making for better control of the muscle.”
For people who have degenerative retinal disease, a new artificial retina looks like it may restore more normal vision than existing retinal prosthetic devices, said Sheila Nirenberg, Ph.D., a researcher at Weill Cornell Medical College in New York.
“Nothing close to normal vision has been possible,” she said. Other devices have focused on increasing the number of cells that are re-activated in the damaged retina, she said. The new device goes beyond that. ”We developed a retinal prosthetic that incorporates the retina’s neural code.”
Nirenberg said it’s not enough to simply stimulate the cells, it’s crucial to stimulate them with the right code–the code the retina sends to the brain that converts pictures into signals the brain can understand.
In the new device, an encoder takes the image and converts it into a code used by the ganglion cells, which receive the visual information from outside. Next, a transducer has the ganglion cells ”fire” according to the code. The result is a more natural image, not just the perception of spots and edges.
The new device reconstructed faces, landscapes and even newsprint, Nirenberg said.
“It jumps the system’s performance up to near-normal levels,” she said. The system has been tested only in animals so far, but Nirenberg plans human studies soon.
Source: Society for Neuroscience