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.



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