In the current study, the prosthetic arm was positioned near the monkey's shoulder and made to simulate natural movement. The monkey moved the arm to bring a piece of fruit to its mouth. The investigators recorded the activity of neurons in the motor cortex, the area of the brain where intentional movements originate, to provide neural control of the robotic device. Each of these neurons has a preference for movement in a specific direction. When a motion is made--or even planned--in a cell's preferred direction, it increases its firing rate, or activity. "This robust relationship between motor cortical cell activity and intended movement direction allows us to use motor cortical signals to control the prosthetic device," says Velliste.

Although the new technology controls the speed and direction of the "hand," computers calculated the details of the arm's movements--such as the joint angles and the forces needed to move the arm. Future work from the group will examine more complex tasks, requiring precise movements of the arm, hand, and fingers. "Eventually, we hope to use this technology to provide disabled patients with the ability to interact naturally with their environment," Spalding says.

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Contact: Leah Ariniello
dawn@sfn.org
202-462-6688
Society for Neuroscience
26-Oct-2004