Directors of the School: Antonio M. Battro and Kurt W. Fischer
Directors of the Course: Sidney Strauss and Elena Pasquinelli
Program officer: María Lourdes Majdalani
Coupled neural systems underlie the production and comprehension of naturalistic narrative speech
Neuroimaging studies of language have typically focused on either production or comprehension of single speech utterances such as syllables, words, or sentences. In this talk I will introduce novel methodological and analytical tools we developed for characterizing the neural responses during production and comprehension of complex real-life speech. First, using a time-warp based intra-subject correlation method, we identified all areas that are reliably activated in the brains of speakers telling a fifteen minute long narrative. Next, we identified areas that are reliably activated in the brains of listeners as they comprehended that same narrative. This allowed us to identify networks of brain regions specific to production and comprehension, as well as those that are shared between the two processes. The results indicate that production of a real-life narrative is not localized to the left hemisphere but recruits an extensive bilateral network, which overlaps extensively with the comprehension system. Moreover, by directly comparing the neural activity timecourses during production and comprehension of the same narrative, we were able to identify not only the spatial overlap of activity but also areas in which the neural activity is correlated (coupled) across the speaker’s and listener’s brains during production and comprehension of the same narrative. We demonstrate widespread bilateral coupling between production- and comprehension-related processing within both linguistic and non-linguistic areas, exposing the extent of shared processes across the two systems. The ability to communicate thoughts to other brains is a hallmark feature of human cognition. The robust production-comprehension coupling observed here underlines the importance of studying comprehension and production within a unified framework. Just as one cannot study the processes by which information is transmitted at the synaptic level by focusing solely on the pre-synaptic or post-synaptic compartments, one cannot fully characterize the communication system by focusing on the processes within the border of a single isolated brain.