Whether a tree branch or a computer mouse is the target,
reaching for objects is fundamental primate behaviour. Neurons
in the brain prepare for such movements, and this neural
activity can now be deciphered, allowing researchers to predict
what movements will occur. This discovery could help us develop
prosthetic limbs that can be controlled by thought alone. To
find out what goes on in the brain when we reach for things,
biomedical engineers Daniel Moran and Thomas Pearce at
Washington University in St Louis, Missouri, trained two rhesus
macaques to participate in a series of exercises. When the
monkeys reached for items, electrodes measured the activity of
neurons in their dorsal premotor cortex, a region of the brain
that is involved in the perception of movement. The monkeys were
trained to reach for a virtual object on a screen to receive a
reward. In some tasks the monkeys had to reach directly for an
object, in others they had to reach around an obstacle to get to
the target. Moran and Pearce managed