Giving a new twist to the phrase wishful thinking, scientists have demonstrated that thoughts alone can enable action. According to a report published today in the journal Nature, a tiny array of electrodes that records, interprets and reconstructs the activity involved in hand motion can harness brain power to control an onscreen cursor.

John Donoghue of Brown University and colleagues tested the system on three rhesus monkeys trained to track a moving image on a video screen using hand movements and a joystick. Implanted electrodes recorded activity in the motor cortex regions of the animals' brains while they performed the task. As the monkeys repeatedly moved the cursor, the scientists developed a series of mathematical formulas that related the firing of neurons to the cursor's position. When the researchers removed the input from the hand console and replaced it with a signal calculated from the implant, the animals continued to successfully track their target. "We substituted thought control for hand control," Donoghue notes, adding that input from as few as six neurons was sufficient for success.

Though not yet approved for human use, this so-called instant-control brain cursor technique may one day form the basis of systems aimed at facilitating communications for paralyzed people. "This implant is potentially one that is very suitable for humans," study co-author Mijail D. Serruya says. "It shows enough promise that it could ultimately be hooked up via a computer to a paralyzed patient to restore that individual's interaction with the environment."