[Paleopsych] Prefrontal cortex brain waves predict body movement

[Steve Hovland]

Scientists Discover What You Are Thinking
PASADENA, Calif. - By decoding signals coming from neurons, scientists at 
the California Institute of Technology have confirmed that an area of the 
brain known as the ventrolateral prefrontal cortex (vPF) is involved in the 
planning stages of movement, that instantaneous flicker of time when we 
contemplate moving a hand or other limb. The work has implications for the 
development of a neural prosthesis, a brain-machine interface that will 
give paralyzed people the ability to move and communicate simply by 
thinking.
By piggybacking on therapeutic work being conducted on epileptic patients, 
Daniel Rizzuto, a postdoctoral scholar in the lab of Richard Andersen, the 
Boswell Professor of Neuroscience, was able to predict where a target the 
patient was looking at was located, and also where the patient was going to 
move his hand. The work currently appears in the online version of Nature 
Neuroscience.
Most research in this field involves tapping into the areas of the brain 
that directly control motor actions, hoping that this will give patients 
the rudimentary ability to move a cursor, say, or a robotic arm with just 
their thoughts. Andersen, though, is taking a different tack. Instead of 
the primary motor areas, he taps into the planning stages of the brain, the 
posterior parietal and premotor areas.
Rizzuto looked at another area of the brain to see if planning could take 
place there as well. Until this work, the idea that spatial processing or 
movement planning took place in the ventrolateral prefrontal cortex has 
been a highly contested one. "Just the fact that these spatial signals are 
there is important," he says. "Based upon previous work in monkeys, people 
were saying this was not the case." Rizzuto's work is the first to show 
these spatial signals exist in humans.
Rizzuto took advantage of clinical work being performed by Adam Mamelak, a 
neurosurgeon at Huntington Memorial Hospital in Pasadena. Mamelak was 
treating three patients who suffered from severe epilepsy, trying to 
identify the brain areas where the seizures occurred and then surgically 
removing that area of the brain. Mamelak implanted electrodes into the vPF 
as part of this process.
"So for a couple of weeks these patients are lying there, bored, waiting 
for a seizure," says Rizzuto, "and I was able to get their permission to do 
my study, taking advantage of the electrodes that were already there." The 
patients watched a computer screen for a flashing target, remembered the 
target location through a short delay, then reached to that location. 
"Obviously a very basic task," he says.
"We were looking for the brain regions that may be contributing to planned 
movements. And what I was able to show is that a part of the brain called 
the ventrolateral prefrontal cortex is indeed involved in planning these 
movements." Just by analyzing the brain activity from the implanted 
electrodes using software algorithms that he wrote, Rizzuto was able to 
tell with very high accuracy where the target was located while it was on 
the screen, and also what direction the patient was going to reach to when 
the target wasn't even there.
Unlike most labs doing this type of research, Andersen's lab is looking at 
the planning areas of the brain rather than the primary motor area of the 
brain, because they believe the planning areas are less susceptible to 
damage. "In the case of a spinal cord injury," says Rizzuto, "communication 
to and from the primary motor cortex is cut off." But the brain still 
performs the computations associated with planning to move. "So if we can 
tap into the planning computations and decode where a person is thinking of 
moving," he says, then it just becomes an engineering problem--the person 
can be hooked up to a computer where he can move a cursor by thinking, or 
can even be attached to a robotic arm.
Andersen notes, "Dan's results are remarkable in showing that the human 
ventral prefrontal cortex, an area previously implicated in processing 
information about objects, also processes the intentions of subjects to 
make movements. This research adds ventral prefrontal cortex to the list of 
candidate brain areas for extracting signals for neural prosthetics 
applications."
In Andersen's lab, Rizzuto's goal is to take the technology they've 
perfected in animal studies to human clinical trials. "I've already met 
with our first paralyzed patient, and graduate student Hilary Glidden and I 
are now doing noninvasive studies to see how the brain reorganizes after 
paralysis," he says. If it does reorganize, he notes, all the technology 
that has been developed in non-paralyzed humans may not work. "This is why 
we think our approach may be better, because we already know that the 
primary motor area shows pathological reorganization and degeneration after 
paralysis. We think our area of the brain is going to reorganize less, if 
at all. After this we hope to implant paralyzed patients with electrodes so 
that they may better communicate with others and control their 
environment."