Through my ongoing collaboration with Joy Hirsch, I was recruited to help her start up a new functional neuroimaging lab at Yale, the Brain Function Laboratory. Our goal in this new lab was to investigate Social Neuroscience using ecologically valid experiments where multiple participants would interact with each other in the real world.
To do this, I needed to first travel to Japan with my collaborators and convince Shimadzu to sell the LABNIRS in North America. After negotiating a partnership with Shimadzu and receiving a fully loaded LABNIRS, we began a series of investigations utilizing hyperscanning fNIRS combined with additional modalities including EEG, eye-tracking and physiology to determine how the human brain responds and interacts in the social world. Early experiments included investigations of dialogues between two individuals who either agreed or disagreed on various controversial topics.
We expanded this to investigate neural correlates of dialog between individuals with high socioeconomic disparity. In the case of agree and disagreement we found that areas of language comprehension showed greater activity compared to agreement . This correlated with several measures of speech including speech rate and fundamental frequency. For individuals with high socioeconomic disparity, we found that the frontal control centers of the brain were active whereas when individuals were of the same socioeconomic status, this was not the case . While we were able to show there were unique areas involved in these exchanges in dialog between partners, we also developed cross-brain synchrony approaches utilizing wavelet coherence between brains to further quantify information exchange in two-person neuroscience . Specifically, in a mutual eye-to-eye gaze task we found that the angular gyrus within the temporal-parietal junction (an area speculated to be the neural hub of social processing) showed specific cross-brain synchrony in live, face-to-face viewing, but not when partners concurrently looked at pre-recorded videos of their partners, or when partners were shuffled or scrambled. This finding argues that cross-brain synchrony in the angular gyrus is specific to live and face to face interactions .