Observed: the precise moment the brain makes a decision
SUNNY SIDE UP or over easy? Train or bus? Cappuccino or latte? Life is full of decisions. Now, researchers at Stanford University have successfully recorded the changes in brain signals that occur when a monkey makes a choice.
The team trained laboratory monkeys to perform a decisionmaking task that involved choosing between two targets on a computer screen. They then tracked the monkeys’ brain signals as the decisions were made. Sometimes the monkeys were able to reach either target, giving them a free choice; at other times one target was blocked, resulting in a forced choice.
By monitoring the monkeys’ motor and premotor cortex using electrodes, the team were able to analyse brain activity during each individual decision. In a sense, they were able to read the monkey’s mind during the free choices, when each decision may be different.
“We can now track single decisions with unprecedented precision,” said Stanford neuroscientist Matthew Kaufman. “Brain activity for a typical free choice looked just like it did for a forced choice. But a few of the free choices were different. Occasionally, he was indecisive for a moment before he made any plan at all, and about one time in eight, he made a plan quickly but changed his mind a moment later.”
The work could lead to more effective control algorithms for neural prostheses, which enable people with paralysis to drive a brain-controlled prosthetic limb or guide a neurally-activated cursor on a computer screen.