The pastor John Calvin, a reformer during the Protestant Reformation, argued humans had free will. Photo by Hans Holbein/Wikimedia
Oct. 2 (UPI) -- Neuroscientists have pinpointed the origin of "free will" inside the human brain.
Whether or not free will exists -- or whether such a distinction is meaningful -- will remain a point of contention among priests and philosophers. What matters to neuroscientists is the interpretation, or perception, of free will. And for the first time, scientists have identified its cognitive origins.
Scientists define free will as the combination of volition, the will to act and agency, a sense of responsibility for one's actions.
Through an analysis method called brain lesion network mapping, scientists were able to pinpoint the origins of the two cognitive processes responsible for the perception of free will.
"Lesion network mapping is a recently validated technique that allows scientists to map symptoms caused by brain injury to specific brain networks," Dr. Michael Fox, a neuroscientist at Beth Israel Deaconess Medical Center, said in a news release. "In this study, we used this network localization approach to determine the neuroanatomical basis for disordered free will perception."
Scientists surveyed the medical literature for brain injuries that disrupted volition and agency. Researchers found 28 cases in which a brain injury caused the patient to lose the motivation to move or speak. The research team also found 50 cases in which a brain injury caused patients to sense body movements were not their own, sometimes called phantom limb syndrome.
Fox and his research partners determined volition disruption was caused by brain lesions on the anterior cingulate cortex, a region of the brain linked with motivation and planning. Most of the brain lesions linked with phantom limb syndrome were found on the precuneus cortex, a brain region linked with agency.
Tests on otherwise healthy patients proved manipulation of the two brain regions interfered with the perception of free will, confirming the conclusions of the mapping effort.
Scientists detailed their findings this week in the journal Proceedings of the National Academy of Sciences.
While the new findings are significant for understanding how different brain regions affect people's perceptions of their actions, authors of the new study don't expect their work to be cited in the courtroom anytime soon.
"Our study was focused on patients with disorders of free will for movements; however, free will is commonly discussed as it relates to social, legal and moral responsibility for decisions, not just movement," said Fox, who also serves as an associate professor of neurology at Harvard Medical School. "It remains unknown whether the network of brain regions we identify as related to free will for movements is the same as those important for moral decision-making."
Earlier this year, scientists identified the origins of bravery inside the human brain.