Human babies prefer to look at faces and pictures of faces more than any other object or pattern. A recent study found that even fetuses in the womb will turn their heads towards dots of light shone through the mother’s skin if the dots broadly resemble a face. Brain imaging studies show that face recognition depends on the coordinated activity of multiple brain regions. A core set of areas towards the back of the brain processes the visual features of faces, while regions elsewhere process more variable features such as emotional expressions.
Around 2% of people are born with difficulties in recognizing faces, a condition known as congenital prosopagnosia. These individuals have no obvious anatomical abnormalities in the brain, and brain scans reveal normal activity in core regions of the face processing network. So why do these people have difficulty with face recognition?
One possibility is that the condition reflects differences in the number of connections (or “connectivity”) between brain regions within the face processing network. To test this idea, BGU researchers and their colleagues compared connectivity in individuals with congenital prosopagnosia to that of healthy volunteers. In the healthy volunteers, an area of the network called the anterior temporal cortex was highly connected to many other face processing regions: that is, it acted as a face processing hub. In individuals with congenital prosopagnosia, this hub-like connectivity was missing. Instead, a number of core regions involved in processing the basic visual features of faces, were more highly connected to one another. The greater this “hyperconnectivity”, the better the individual’s face processing abilities.
The findings pave the way for developing imaging-based tools to diagnose congenital prosopagnosia. The same approach could then be used to investigate the basis of other neurodevelopmental disorders that are thought to involve abnormal communication within brain networks, such as developmental dyslexia.
“This study provides a 'bird's eye' view of the face network that sheds new light on critical questions, such as what aspects of the network architecture underlie normal face representation and what aspects of the network are compromised when face perception is impaired,” says primary investigator Prof. Galia Avidan.
BGU’s Avidan of the Department of Psychology, the Department of Cognitive and Brain Sciences and the Zlotowski Center for Neuroscience led the study. Avidan’s PhD student, Gideon Rosenthal, was first author and her former post-doc Michal Tanzer was a co-author. Avidan and her students collaborated with Prof. Uri Hasson from Princeton University, Prof. Marlene Behrmann from Carnegie Mellon University, and Dr. Erez Simony of the Holon Institute of Technology, and the Weizmann Institute of Science.
The study was funded by the Israel Science Foundation and the US National Science Foundation.
