Primate research may lead to human cyborgs

A team of researchers from Stanford University took the time to examine how monkeys’ brains control unplanned arm movements, in order to develop better brain-controlled prosthetic limbs (and to keep their engineers from going bananas).

 

 

Monkeying around

 

The study, which was published in the online neuroscience journal Neuron, discusses the findings of Professor Krishna Shenoy, Dr Stephen Ryu, and neuroscience doctoral student Katherine Cora Ames. The researchers conducted a series of tests on monkeys in order to determine and compare the level of activity in their brains during planned and reactive (unplanned) arm movements.

 

The simian subjects were conditioned to touch a target whenever it appeared on a screen. The team recorded the electrical activity of the monkeys’ neurons that control motor and premotor functions during three sets of experiments.

 

The first set involved training the monkeys to wait until they get the “go” signal to touch the target on the screen. Called a “delayed experiment reach,” this filled the role of the “planned action” in the study.

 

During the second set, the monkeys were supposed to anticipate the target’s appearance on the screen and touch it immediately. The data collected from this phase fell under the “unplanned action” part of the experiment.

 

The third set, however, involved a little trickery on the part of the researchers. In this iteration, the target’s position was changed – it was moved to a different location on the screen, forcing the monkeys to react quickly.

 

Simian secrets

 

The researchers discovered that the monkeys already had an idea about the kind of arm movement they were supposed to make; the subjects were simply waiting for the appropriate signal to touch the screen. According to the scientists, the monkeys’ neurons went into a “prepare and hold” state – the brain’s “ready, set, go” condition – before making planned actions.

 

However, the monkeys’ neurons did not go through “prepare-and-hold” whenever the monkeys made unexpected arm movements, surprising the Stanford researchers. This helped to disprove the researchers’ previous notion that undergoing a “prepare-and-hold” state was a prerequisite to motor functioning.

 

Ames affirmed that awareness of the target was always the first information to reach the neurons. However, the differences between the set involving planned actions and the other two sets involving unplanned actions became apparent roughly 50 milliseconds after electrical readings of perception: while the first set showed a definite “ready, set, go” phase for the monkeys, the other two appeared to skip “ready” and “set,” jumping straight to “go.”

 

“This study changes our view of how movement is controlled,” revealed Ames. “First you get the information about where to move. Then comes the decision to move. There is no specific prepare-and-hold stage unless you are waiting for the signal to move.”

 

Professor Shenoy is confident that their findings have both theoretical and practical uses. “In addition to advancing basic brain science, these new findings will lead to better brain-controlled prosthetic arms and communication systems for people with paralysis,” said Shenoy, who is currently working on electronic systems that convert neural activity into electrical signals for controlling artificial limbs.

 

Here's hoping that any further experiments on monkey brains won’t result in a Blue Monkey infestation, though. They were bad enough in System Shock 2. — TJD, GMA News