Research in the Hirsch Lab at the Yale School of Medicine aims to understand the neural circuitry and fundamental mechanisms of the brain that enable human cognition, language, emotion, decision making, and perception in both healthy/typical individuals and in patients with neurological, developmental, and psychiatric disorders. While ongoing and previous fMRI studies focus on segregated and distributed neural processes within single individuals, the Brain Function Laboratory is also expanding the experimental paradigm from a single-brain frame-of-reference to a multi-brain frame-of-reference using near-infrared spectroscopy, NIRS. The investigation of neural complexes associated with dynamical brain-to-brain/person-to-person communications is largely unexplored. For these investigations, Blood-Oxygen-Level-Dependent, BOLD, signals acquired by NIRS; electroencephalographic, EEG, signals; and eye-tracking data are acquired simultaneously on multiple individuals using surface optodes and electrodes respectively. These neuroimaging measures are synchronized with eye-tracking and physiological measures obtained by head mounted cameras and physiological sensors. Models of dual-brain interactions are based on coherence between wavelets of signals originating from cross-brain pairs of regions. Advances build upon theoretical, technical, and methodological foundations of behavioral and functional neuroimaging studies in the laboratory, and open a novel window-of-opportunity to investigate the neural correlates of dynamic interactions between individuals under natural (ecologically valid) conditions. The Brain Function Laboratory is currently focused on specific studies of dynamic coalitions and neural operations that regulate inter-personal dialog and social interactions including conflict, competition, cooperation, non-verbal communications, music and communication, and the role of mutual gaze and faces in interpersonal interactions. A long-term goal is to understand the neural correlates of dynamic social behavior. The Brain Function Laboratory was established at Yale University in 2013 under the direction of Professor Joy Hirsch following a transition from Director of the fMRI Research Center within the Program for Imaging & Cognitive Sciences (PICS) at Columbia University in New York. The Brain Function Laboratory website is located at http://www.fmri.org.