Brain Network Localization of Free Will
News Oct 03, 2018 | Original Story from the Beth Israel Deaconess Medical Center
Long the domain of philosophy and religion, free will has also been defined by scientists as a combination of two cognitive processes – the desire to act (or volition) and the sense of responsibility for our actions (or agency.) Together, these processes create the perception of free will, and damage to volition or agency can leave patients without the desire to move or speak or the sensation that their movements are not their own, respectively.
Neuroscientists led by Michael Fox, MD, PhD, of Beth Israel Deaconess Medical Center (BIDMC) used brain lesion network mapping – a technique pioneered by Fox at BIDMC – to find the anatomical origins of the perception of free will. Their findings were published today in the Proceedings of the National Academy of Sciences.
“Lesion network mapping is a recently validated technique that allows scientists to map symptoms caused by brain injury to specific brain networks,” said Fox, Director of the Laboratory for Brain Network Imaging and Modulation at BIDMC and an Associate Professor of Neurology at Harvard Medical School. “In this study, we used this network localization approach to determine the neuroanatomical basis for disordered free will perception.”
Fox and colleagues, including lead author, R. Ryan Darby, MD, PhD, formerly a fellow in Fox’s lab at BIDMC and now of Vanderbilt University Medical Center, identified 28 cases in the medical literature in which brain injury disrupted volition, leaving patients with akinetic mutism – a lack of motivation to move or speak. They also identified 50 cases in which brain injury disrupted agency and caused patients to feel their movements were not their own, a syndrome known as alien limb syndrome.
Network mapping revealed that, while the brain injuries were quite diverse in their locations, the lesions fell within one of two distinct brain networks. All of the injuries disrupting volition were functionally connected to the anterior cingulate cortex, a region of the brain associated with motivation and planning. Ninety percent of lesions causing alien limb fell within a brain network functionally connected to the precuneus cortex, part of the brain associated with agency.
Finally, the authors showed that their findings were relevant beyond patients with brain injury. Brain stimulation to these same sites altered free will perception in healthy research participants, and neuroimaging of psychiatric patients with altered free will perception revealed abnormalities fell with these same brain networks.
“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. “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.”
This article has been republished from materials provided by The Beth Israel Deaconess Medical Center. Note: material may have been edited for length and content. For further information, please contact the cited source.
Adult depression has long been associated with shrinkage of the hippocampus, a brain region that plays an important role in memory and response to stress. Now, new research has linked participation in team sports to larger hippocampal volumes in children and less depression in boys ages 9 to 11.
Researchers have discovered a brain process common to sleep and ageing in research that could pave the way for new treatments for insomnia. The scientists report how oxidative stress leads to sleep. Oxidative stress is also believed to be a reason why we age and a cause of degenerative diseases.READ MORE
Patients in a new Northwestern Medicine study were able to comprehend words that were written but not said aloud. They could write the names of things they saw but not verbalize them. This provides an insight into the brain degeneration that defines the rare dementia termed primary progressive aphasia.