Control of octopus arm extension by a peripheral motor program

For goal-directed arm movements, the nervous system generates a sequence of motor commands that bring the arm toward the target. Control of the octopu s arm is especially complex because the arm can be moved in any direction, with a virtually infinite number of degrees of freedom. Here we show that a rm extensions can be evoked mechanically or electrically in arms whose conn ection with the brain has been severed. These extensions show kinematic fea tures that are almost identical to normal behavior, suggesting that the bas ic motor program for voluntary movement is embedded within the neural circu itry of the arm itself. Such peripheral motor programs represent considerab le simplification in the motor control of this highly redundant appendage.