Functional Connectivity of the Language and Non-Language Brain Networks During Language Task

Language is a specific cognitive function which is represented by highly specialized regions of the cerebral cortex. It is well-established that language network is usually left-lateralized in the brain. The majority of right- and left-handed people show left language lateralization, while in a substantial minority of the population bilateral and right patterns of language lateralization are observed. The relationship between language lateralization and properties of global functional brain organization is one of the most topical areas in neuroimaging research. Language lateralization is associated with alterations in functional structure of the language network itself, as well as in patterns of functional connectivity between language and non-language regions. Their special functional relation is especially salient in the studies of structural and functional interaction of the language network with the associative areas of the brain. Moreover, speech lateralization is associated with common functional and structural differences between brain hemispheres. This paper examines the functional connectivity of the language and non-language brain networks in healthy subjects during language task. We applied independent component analysis to fMRI data collected from 50 healthy participants. We identified the components which correspond to the language network and general-domain cognitive networks. A significant correlation was expected between the measures of language lateralization and coefficients of functional connectivity between language and non-language networks. In individuals with atypical language lateralization,we suggested greater functional connectivity between language and non-language brain areas. Although the expected correlation between functional connectivities and language lateralization was not found, our study demonstrates that during language task, the language network is positively functionally connected to one of the default mode subnetworks, and negatively functionally connected to the right frontoparietal network. Functional connectivity related to language processing was also found between the default mode subnetworks and the frontoparietal subnetworks. Previous studies have demonstrated a complex system of functional interactions between the default mode network and the frontoparietal network at resting state and during cognitive tasks. Our study shows similar results during language-specific task. Overall, our study contributes to our knowledge of the complex functional interaction between language network and associative brain structures.