Everyday facial expressions such as smiling or showing surprise seem automatic, but recent research indicates that the brain orchestrates these movements through a complex network of signals. A new study published in Science challenges the long-held belief that separate brain systems control voluntary and emotional facial gestures.
The research was led by Professor Winrich A. Freiwald from The Rockefeller University in New York and Professor Yifat Prut from ELSC at Hebrew University, with contributions from Dr. Geena Ianni and Dr. Yuriria Vázquez of The Rockefeller University.
For years, scientists thought that lateral cortical areas in the frontal lobe were responsible for deliberate facial movements while medial regions controlled emotional expressions. This idea was based on clinical observations of people with localized brain injuries.
However, by directly recording activity from individual neurons across both cortical regions, the researchers found that both areas are involved in producing voluntary and emotional gestures. Notably, these neural patterns are distinguishable even before any visible movement occurs.
The findings suggest that facial communication is coordinated by a continuous neural hierarchy where different regions contribute information at varying time scales—some dynamic and fast-changing, others stable and sustained. These area-specific timing patterns form a continuum that enables coherent facial gestures tailored to context, whether deliberate or spontaneous.
"Facial gestures may look effortless," the researchers note, "but the neural machinery behind them is remarkably structured and begins preparing for communication well before movement even starts."
This new understanding could inform approaches to restoring or interpreting facial communication following brain injury or in conditions affecting social signaling. The study offers a framework for future exploration into how socially meaningful behavior is produced by parallel processing within the brain.
