Alterations in functional connectivity between frontal cortex and other brain regions has been demonstrated in schizophrenia patients using a variety of techniques, some of which specifically isolated task-dependent connectivity changes (57–59), and others which did not (22,54,56,60). Of these, the only studies that attempted to distinguish between generalized and task-dependent connectivity changes have been those using dynamic causal modeling, which allows assessment of group differences in task-related causal interactions (effective connectivity), as well as so-called endogenous, or context-independent, connectivity, between specific regions of interest (61,62) (Section S1 in Supplement 1). This work has identified altered effective connectivity between frontal and other brain regions at different illness stages of schizophrenia and across a range of paradigms, including those assessing perceptual discrimination (23), memory (25), and cognitive control (26,63), but the most replicated differences have been for the context-independent endogenous connectivity parameters. These results concur with our finding of a widespread and generalized connectivity deficit in schizophrenia, which particularly affects functional integration between frontal cortex and other regions. Measuring connectivity differences across a range of tasks in the same sample will help
