This is an individual National Research Service Award for pre-doctoral research training, which provides support for promising doctoral candidates who will be performing dissertation research and training in a scientific health-related field. Many mental health disorders (e.g., autism, schizophrenia, major depressive disorder) are associated with impairments in communication, emotion processing, and social functioning. The aim of this research proposal is to examine the neural systems necessary for interpersonal coordination, a process important for effective and efficient communication and emotion processing, and involves the ways in which people coordinate and adapt the timing and similarity of their behaviors during social interaction (e.g., when to talk or gaze; adopting similar postures and facial expressions). The proposed studies will be conducted with brain injured individuals with stable and circumscribed lesions, which enable characterization of the specific brain regions necessary for interpersonal coordination. The second aim of this study will develop ecologically valid methods for the rehabilitation and treatment of interpersonal coordination impairments in brain-damaged individuals, which may positively influence social communication and can be adapted for other clinical populations. Better understanding of the neural and psychological mechanisms underlying this important process for communication, empathy, and developing rapport can better inform the mechanisms and treatment of complex mental health disorders such as autism and schizophrenia.