Free will is considered the domain of philosophers, but this long lasting question might actually be put to rest by neuroscience. In a most intriguing research, a team at Stanford analyzed the key brain motor patterns in monkeys as they made specific decisions, and eventually recorded the moment-by-moment patterns that lead to change of mind. Apart from its philosophical implications, which really might never be settled, the findings prove extremely useful for brain-computer interfaces and the likes. Controlling robotic arms with your thoughts, or just about anything really, is no longer a provision of science fiction. Still, this basic neuroscience discovery could be used to improve brain-computer algorithms and thus refine control of thought controlled prostheses such that a robotic arm or leg might be moved only when the user is certain of its decisions, thereby avoiding premature or inopportune moments.
Decisions, decisions
The experiments were led by Professor Krishna Shenoy, whose lab at Stanford focuses on developing cutting edge neural prostheses. Shenoy was aided by neuroscientist Matthew Kaufman, while the latter was a graduate student in Shenoy’s lab. Kaufman trained two monkeys to choose between two targets on a computer screen. The monkey could either choose any between the two targets, or forced to choose one (single variable) since the other one was rendered inactive. At other times, however, the configuration was switched fro two choices to one or vice-versa to stimulate change of mind.
To stimulate decision making processes even further, the targets on the screen would first jitter and once they would settle, the monkey had to follow a simple maze on screen with its finger to select the chosen target. During the whole process, 192 electrodes measured activity in each monkey’s motor and premotor cortex, beginning with the moment the target appeared on the screen, and ending at the monkey’s first sign of movement, so as to gauge activity related to decision making processes only. An single-trial decoder algorithm was then used to processes the gathered information for each individual decision. Effectively, Shenoy and Kaufman were reading the monkeys’ minds while they were forming a decision.
“We can now track single decisions with unprecedented precision,” Kaufman said. “We saw that the 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. About one time in eight, he made a plan quickly but spontaneously changed his mind a moment later.”
“We are seeing many cognitive phenomena in the brain for the first time,” said Kaufman, who is now a postdoctoral scholar at Cold Spring Harbor Laboratory. “The most critical result of our work here is that we can track a single decision and see how the monkey arrived there: whether he decided quickly, slowly, or changed his mind halfway through.”
By refining the experiment, scientists hope to come to a better understanding of how decision making takes place in the brain. We take these sort of processes for granted, since our minds and bodily parts are so synchronized that there’s no room left for ambiguities. When dealing with a foreign neurally connected body, like a mechanical arm, instructions may be hampered by noise or mixed decisions that are difficult for the neural prosthesis to interpret. Findings appeared in eLife.
“This basic neuroscience discovery will help create neural prostheses that can withhold moving a prosthetic arm until the user is certain of their decision, thereby averting premature or inopportune movements,” Shenoy said.
