Brain regions involved in the perception of gaze: a PET study

Mutual gaze may be described as a psychological process during which two persons have the feeling of a brief link between their two minds. In the monkey, specific cell assemblies in the superior temporal cortex of the brain are responsive to gaze. This suggests that the brain may have evolved mechanisms for interpreting direct eye contact. These mechanisms could depend on the activation of specific brain regions. Positron emission tomography was used to measure activity in brain regions in healthy volunteers while they were looking at faces featuring, respectively, eye contact, averted gaze, or no gaze. As expected a region known to be involved in face processing was found to be activated in the ventral occipito-temporal region, especially in the right hemisphere. Averted gaze and mutual gaze triggered blood flow responses in similar areas which were different from those involved in face processing. These areas included the occipital part of the fusiform gyrus, the right parietal lobule, the right inferior temporal gyrus, and the middle temporal gyrus in both hemispheres. These results are consistent with the hypothesis that perception of eyes regardless of the direction of the gaze is subserved by a distributed network. However, no conclusive evidence was found for specific area(s) devoted to mutual gaze processing.