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Monkey See, Monkey Mind Controls Arm

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Dr. Lee Miller, a Goshen College alumnus, and fellow GC graduate Matt Bauman are working, along with other researchers, towards major advancements in long term paralysis treatment. Their team’s research with brain-controlled muscle simulation was recently mentioned as one of the top 10 break-throughs of 2012 by Science Magazine.

Over the past few years, these researchers at Northwestern University in Chicago have been steadily working on projects which have the potential to help countless people. At Dr. Miller’s laboratory, their innovative approach combines Brain Machine Interface technology with Functional Electrical Stimulation. 

How exactly does their project work? First, a multi-electrode spread is surgically placed above the motor cortex of Thor. (That’s in the test subject monkey’s brain.) Thor’s arm is then temporarily paralyzed by the injection of a nerve block agent into the nerves near the elbow.

The monkey, having been previously trained to pick up and deposit a ball, then attempts to do just that, but without success given that his arm has been temporarily disabled. During this process of trial and error, Dr. Miller and his fellow researchers record the signals from Thor’s brain through the surgically implanted microelectrodes, which serve the purpose of relaying the brain signals to a computer for analysis.

What makes Miller and company’s research unique from other researchers also using brain machine interface technology is what they then do with this information. Instead of using it to move a cursor on a computer screen or to control a robot, these neurologically-transmitted signals are used to reanimate the monkey’s arm, bypassing the monkey’s spinal cord and the normal anatomical route of brain to nerve to muscle simulation.

As Miller describes it: “The novel aspect of our work is that we are reanimating the monkey’s own limb, where most other research groups are using similar methods to move an inanimate robot arm.”

How is this possible? The secret lies in how the team thought about the problem. Instead of using received brain signals to try to predict what the monkey was going to do and then reposition the arm–a very end-minded result approach–the problem was thought about from the middle. The research team reasoned that since muscles contract in a pattern, which in the end causes motion, they could stimulate the muscles of the monkey based upon the brain signals from the motor cortex.

“It’s similar to the typical high-school experiment of shocking a frog’s leg to get it to twitch, except in a very controlled manner,” Miller said. The research team uses FES technology, or functional electrical stimulation, which The Cleveland FES Center describes as being able to “produce and control the movement of otherwise paralyzed limbs for standing and hand grasp[ing].”

By predicting the extent of Thor’s muscle ability, Dr. Miller’s team uses the brain signals transmitted to the computer to stimulate the before-paralyzed muscles of the monkey using FES technology, all without involving the monkey’s spine. The monkey was able to perform the motions involved with grasping the ball, picking it up, and moving it to the machine where the ball was placed, albeit with some understandable limitations. Thor was able to complete the tasks about 80% of the time, all while having one arm afflicted with conditions similar to that of spinal-cord injury sufferers.

As of now, the monkey is not able to grasp things as strongly or to activate all the muscles involved in the same action as well as a non-disabled arm. Much of this is because the motor cortex is not yet completely understood. These imperfections of the experiment, coupled with the positive results, only serve as motivation for the research team.

Currently, they are working on three fronts to improve their experiment and to better understand its implications. At the moment, not all muscles in the arm can be accessed by surgical implementation, especially those located in the hand. Peripheral nerve stimulation technology is thus in the works.

Another aspect of research is in technology that could allow the monkey to be under the test conditions 24/7. Presently, the effects of the applied local anesthetic only last for an hour or two at best, much like getting work done at a dentist’s office. The development of longer-lasting means could allow the research team to observe the monkey as it adapts to living with the experimental muscle control (neuroprosthesis) in all of its day-to-day activities.

The third area for improvement is measuring the brain activity for the experiments. Part of the motor cortex lies on a region of the brain very easily surgically accessible, much like a window into a house. This is the area used in Miller’s published research. However, the motor cortex extends some nine millimeters farther into the brain, where it is less accessible, but is thought to be even more integral in controlling the monkey’s muscle activity. Miller believes this to be a promising area of improvement.  “We are actually planning to implant electrodes in this region next month, in preliminary experiments,” Miller said.

In relation to his career, Miller is keen to point out that his days in Goshen, and his experience learning at Goshen College, are not something to be understated. “My work is new every day. Getting a Bachelor of Arts degree instead of a Bachelor of Science degree allowed me to have exposure to a much broader range of studies and experiences. For multidisciplinary research like this, that is really helpful,” Miller said. “Keeping curiosity alive in as many areas as you can is very important,” since that can often be lost behind in the technical components of science.

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