New research from scientists at Queen's University has revealed that the brain prepares multiple movement options simultaneously before deciding on the best one, helping to explain how it represents and ultimately chooses from potential actions in the moment.
"Although there is an increasing appreciation among neuroscientists and psychologists of how processes involved in movement planning and control shape decisions, what has been missing is convincing behavioral evidence that can ground interpretations of neurophysiological data," Jason Gallivan, who participated in the research, said in a press release.
Every time a person conducts a reaching movement, it is supported by reflex responses in the case of any errors. For example, if you reach for your coffee much and your hand is off course, the brains "visuomotor" reflex well generate a command for the error, allowing us to still grab the mug.
One of the most important aspects of this planning process is determining the "gain" of the reflex - in other words, if the reflex is more complex and the reaching movement requires higher levels of correction, the gain is higher.
In the current study, the team found that when subjects had to reach for two potential targets, one wide (low gain) and one narrow (high gain) that were superimposed, the gain of the reflex was the average of the two gains that they obtained when testing the subjects on the targets individually. This indicates that the brain planned a movement for each target and when the target was uncertain, it stimulated the subjects to conduct them simultaneously.
"Preparing multiple plans may facilitate rapid movement initiation once one plan is selected, and may also provide a mechanism through which movement-related factors can influence the decision about which movement to make," said Randy Flanagan, who also participated in the research. "Understanding how the brain initially represents and decides between competing action options in the environment is a fundamental question in the neurosciences of decision-making and motor control."
The findings were published in the Jan. 11 issue of Nature Neuroscience.
