Task-dependent changes in functional connectivity during the observation of social and non-social touch interaction

Previous studies have identified a collection of brain areas that show neural selectivity for the distinction between human-to-human and human-to-object interactions, including regions implicated in sensory and social processing. It remains largely unknown, however, how the functional communication between these areas changes with the type of interaction. Combining a generalized psychophysiological interaction (gPPI) analysis and independent component analysis (ICA), the current study sought to identify the context-sensitive modulation of the functional network architecture during touch observation. Thirty-seven participants watched 75 video clips displaying social and non-social touch events during a functional imaging scan. A gPPI analysis of pre-defined regions of interest revealed that social-cognitive brain regions show enhanced interregional coupling during social touch observation, both among social-cognitive brain regions and between social-cognitive regions and sensory regions. Conversely, during non-social touch observation, a significantly stronger coupling among brain areas within the system that processes the unimodal sensory information was observed. At the level of large-scale brain networks extracted with ICA, stronger connectivity between 11 pairs of networks, including default mode networks, was observed during social touch observation, while only three pairs of networks showed stronger connectivity during non-social touch observation. The current study identifies the presence of context-dependent changes in functional brain architecture based on whether the touch recipient is a person or an object, highlighting an increased exchange of neural information for social processing.