Touching the Void - Part 2

By Dr. Lise Johnson (CSNE Education Manager)

jeff ojemann

Jeff Ojemann’s father is a neurosurgeon, and his mother is a neurologist, which means he was exposed to brain science from a young age. There is a funny story his family tells about how, as a young child, Ojemann found a brain anatomy book his mother had left out, and after reading it he mispronounced “cerebellum” as “cere-button” (many children have trouble with pronunciation; when I was a small child I couldn’t pronounce my own name). So, you might think that he always wanted to be a neurosurgeon, or a neurologist, or some sort of doctor, but in fact, he did not. He wanted to be a physicist. To prove this was so, Ojemann went to Princeton and got a Bachelor of Science degree in physics. He liked physics, especially thermal physics. He liked it so much, in fact, that he still has his textbooks (although it isn’t clear whether he spends much time reading them anymore). But, Ojemann didn’t feel like being a physicist was the most he could do for people; he thought he would be more useful to the world as a medical doctor. So, he went to medical school, but without any intention of becoming a neuro- anything. However, when he did his neurosurgery rotation he found that he really liked it. Rather than fight it, he became a neurosurgeon. When I asked him if he thought there was a genetic component to his interest, he said no, and no one in his family ever pressured him to become a physician. But, he does believe that examples are important, and having his parents as examples showed him that it was possible to be a brain doctor if that was what he wanted to be.

Ojemann went to Washington University in St. Louis for medical school and stayed for his residency. While he was there he also got a Master’s degree in biomedical science. As part of his training he became involved in neuroscience research; in particular he was part of group that was using new imaging techniques to see how different parts of the brain worked together in real time. He wasn’t really involved in any neural engineering, though. When he took a faculty position at the University of Washington, Ojemann established his own research group, and while he continued to be involved in a lot of basic neuroscience research, he also started to branch out. One of the reasons for this was that he recognized an opportunity. As an epilepsy surgeon, Ojemann regularly puts electrodes right on the surface of the human brain. These electrodes are used to record the electrical activity produced by the neurons, and also to electrically stimulate the brain. Many of Ojemann’s patients are willing to volunteer for research studies, meaning that he has access to a kind of data that is both rare and valuable, not only for basic neuroscience research, but also for neural engineering applications. Ojemann recognized that he had an opportunity to investigate brain-computer interfaces with these patients, and that is how he became a neural engineer.

My last post included a brief discussion of the Montreal Procedure; a surgical procedure used to treat certain kinds of epilepsy. This treatment was developed by a neurosurgeon named Wilder Penfield in the 1930s, at which point it as very cutting edge (no pun intended). However, many things in the world have changed in the last 80 years, and not surprisingly, the surgical treatment of epilepsy is one of those things. A large part of this change is attributable to advances in related technologies. For example, there has been a lot of action in the domain of medical imaging. In the 1930s, medical imaging consisted entirely of single film X-ray. Now, we have X-ray computed tomography (CT scans), positron emission tomography (PET scans) and magnetic resonance imaging (MRI). MRI scans in particular have been widely adopted for brain imaging because they make it possible the look inside the brain without making any incisions (which is nice) and without using any radiation (also, quite nice). MRI got even more useful when it was discovered that brain activity could be measured using functional MRI (fMRI). This new ability to visualize the brain non-invasively has made it possible for physicians to provide better, more targeted treatments. It has also made more people with epilepsy candidates for surgical intervention (where surgical intervention means having the damaged part of their brain removed), and as a result more people are getting this kind of brain surgery.

Another difference is that many of these patients now receive long-term electrocorticography (ECoG) monitoring prior to their resection surgery (the resection is the removal of the damaged brain tissue). ECoG monitoring involves surgically implanting a large number of electrodes on the surface of the brain, under the skull but not penetrating the brain tissue. Typically, patients have this implantation surgery one or two weeks before the resection, and they have to spend those one or two weeks between surgeries in the hospital. The electrodes record the activity of the brain during seizures, and this information can be used to map the seizure source passively (that is, without electrical stimulation).

So, Ojemann’s patients undergo a new procedure for the surgical treatment of epilepsy, and it goes like this:

  1. The person with epilepsy (the patient) undergoes MRI and EEG scans to determine whether a resection surgery would be useful,
  2. A grid of electrodes is surgically implanted on the surface of the patient’s brain,
  3. The patient spends 1-2 weeks in the hospital while their brain activity is constantly monitored,
  4. Neurologists analyze the data recorded by the electrodes to determine the precise location of the seizure-causing brain tissue,
  5. The neurosurgeon takes out the electrodes and removes the seizure-causing tissue.

Although the sources of the seizures are mostly determined by passive recordings, there is still a place for electrical stimulation in these patients’ clinical care. This is because electrical stimulation is still the gold standard for mapping brain function. Mapping brain function is quite important because, while there are no unimportant parts of the brain, it is harder to recover after damage to some parts than others. Electrical stimulation mapping is primarily used to identify the parts of the brain that are involved in language and motor control because these are the parts that the surgeon especially does not want to remove or damage.

The result of this new surgical treatment paradigm is a group of people with implanted electrodes who have their brains electrically stimulated as part of their medical care. If you recall, this is exactly what we need in order to answer the question of whether or not electrical stimulation could be used to provide somatosensory feedback for a brain-computer interface. That means Ojemann is poised to answer the question. How he does that takes a little more explanation, which is what I’ll go into in my next post.