The debate has been raging for a long time as to whether neuronal action sequences come before or after the human brain decides what to do. According to a new study, the brain works ahead of human actions by making suitable backup plans anticipating all actions.
The research says that this is how physical movements are executed smoothly: The brain always prepares a plan B by factoring in the upcoming options of different actions.
A clash of options in action patterns is experienced by everyone in moments of hesitation. These may occur in situations such as crossing the road and changing lanes when driving. In such indecisive moments, the brain makes backup plans so that any possible action can be smoothly executed by keeping the neurons in full readiness.
One simple example may be the ambivalence faced at a milk store - to buy a gallon or small pack of milk. Even while the indecision lingers, the brain makes the neuronal sequence ready to execute the action in either case.
The findings published in Cell Reports underscore that the human brain interprets reality as a series of potential actions and always keeps a plan B ready.
According to the researchers, when two options are offered, motor neurons in the brain get ready for both scenarios before the actual action is decided.
Visual Targets Becoming Actions
"The brain is continuously translating visual targets into actions that can be performed on those targets," said Jason Gallivan, co-author and a neuroscientist at Queen's University in Ontario, Canada.
He said the brain's motor system might be operating in the background without being consciously aware of the potential actions that follow.
The researchers deduced results from experiments in which Gallivan and team set up a task for 16 volunteers to move a cursor toward one of two targets on a computer screen using a mouse. The participants couldn't see their hands and their vision was limited to the screen. They were then asked to start the action before they were told which target they have to pick.
Analyzing the action of volunteers, Gallivan noted that when forced into action without a given target, the participants will move their cursor in a line at the middle of the targets.
This is because two plans are specified for the brain and participants have to switch between the two and execute one quickly, noted the main researcher. After telling the participants which target to pick however, the researchers manipulated the cursor, causing it to shift slightly and not follow the motions done by the participants. The researchers observed that the participants were able to adjust their hand movement to compensate for the shift in cursor position.
Perception Through Series Of Actions
The experiment allowed the researchers to determine whether planning a certain movement is done by the brain automatically. They were able to test how the brain works in terms of visual averaging and motor averaging.
Gallivan said the team was surprised to see the vital relationship between the two and noted that the spatial averaging behavior has reinforced that the brain perceives the world in a train of actions and objects.
"This finding indicates that the competing potential targets were rapidly and automatically mapped onto the corresponding motor representations prior to movement selection," the researchers said.