Establishing task- and modality-dependent dissociations between the semantic and default mode networks

• DOI: 10.1073/pnas.1422760112
• Publication Date: 2015-06-10T17:23:59Z
• Authors: Gina F. Humphreys; Paul Hoffman; Maya Visser; Richard J. Binney; Matthew A. Lambon...
• Keywords: Brain Mapping; semantic network; Magnetic Resonance Imaging; Semantics; default mode network; 03 medical and health sciences; 0302 clinical medicine; angular gyrus; Humans; distortion-corrected fMRI; anterior temporal lobe

SignificanceFunctional neuroimaging has established that most cognitive functions are supported by distributed neural networks. Hundreds of studies have investigated the semantic network (SN) and the default mode network (DMN) (neural deactivation when undertaking a variety of tasks). These stable networks are increasingly used as biomarkers in neurological and psychiatric investigations. Despite implicating overlapping neural regions and shared cognitive mechanisms, the relationship between the two networks has received minimal attention. Analyses of a large multitask distortion-corrected functional MRI (fMRI) dataset established that both networks fractionate, depending on the semantic nature of the task, stimulus type, modality, and task difficulty. The implications for the SN, variability in the DMN and its cognitive coherence, and interpretation of resting-state fMRI data are discussed.