Brain Computer Interface for Paralysis

Researchers have recently published results from a study using a brain computer interface. It is a brain computer chip implant that has mobile electrodes. These electrodes are able to interface with single brain cells inside someone's brain and can read their signals. This device may allow people to move who are currently paralyzed due to spinal cord injuries. They have tested this device in monkeys already. The researchers found that the new device allowed the monkeys to overcome wrist paralysis.

The results of this experiment have just been reported in "Nature". You can read the press release here. The scientists basically used a brain computer interface that connected the motor cortex of the monkey to the muscles in their wrist. The motor cortex is a brain region that is located near to a subject's skull. This area is involved in the movement of several parts of the body such as the mouth, the tongue, the lips, hands a several other things. The device sends electrical impulses from the motor cortex to the muscles in the monkey's hand. This route bypasses the normal route of brain to wrist signaling. Brain computer interfaces such as this are nothing new. However there are some intriguing findings from this new study.

Until now, brain-computer interfaces were designed to decode the activity of neurons known to be associated with movement of specific body parts. Here, the researchers discovered that any motor cortex cell, regardless of whether it had been previously associated with wrist movement, was capable of stimulating muscle activity. This finding greatly expands the potential number of neurons that could control signals for brain-computer interfaces and also illustrates the flexibility of the motor cortex.

In the past researchers have attempted to read signals of brain regions in the motor cortex that are directly involved in moving the specific parts of the body that they want to control (fingers, lips, hands etc.). However this new study indicates that it doesn't necessarily matter what area of the motor cortex is targeted. Brain regions not normally associated with moving a specific appendage can be retrained to move them anyway. This shows that the brain is extremely flexible and may make it easier to create better brain computer interfaces. It might not even be necessary to target the motor cortex. Targeting brain regions not even remotely related to the motor cortex area might in theory allow someone who is paralyzed to move as well.

Moritz, CT, Perlmutter, SI, and Fetz, EE. "Direct Control of Paralyzed Muscles by Cortical Neurons." Nature, published online October 15, 2008.