Online social media has become an integral part of our social lives. Online social interactions are distinct from face-to-face interactions. Different social media types have enabled novel forms of social exchanges to take place. Individuals vary greatly in their online behaviors and preferences. The current research argued for the significance of understanding individual differences in social media behaviors from brain structure variability. Using a novel approach that combined methodologies from personality and neuroscience, this research found that variations in social media behaviors and preferences were reliably reflected in brain structure. Interestingly, the general preference for an online mode of social interaction reflected decreased volumes of grey matter in regions involved in facial and speech processing. The associations between patterns of media behaviors and brain structure obtained in this research had demonstrated the feasibility of adopting a neuroscience approach to explain the complex differences in media behaviors.