The role of effective connectivity between the task-positive and task-negative network for evidence gathering [Evidence gathering and connectivity]

Dynamic switching between intrinsic and extrinsic mode networks as demands change from passive to active processing

“…Considering that the DMN in essence is a task-negative network 2,5,35,36 being up-regulated in periods of absence of specific processing demands, it is an www.nature.com/scientificreports/ intrinsic mode network. We now provide more evidence that the brain may alternate between an intrinsic and extrinsic mode of function, corresponding to the dominating environmental demand, with the intrinsic mode network dominating during task-absence, and the extrinsic mode network dominating during task-presence as has been previously suggested 18,19,35 . Interestingly, our results also show that the two networks are sometimes positively correlated, suggesting that the relationship between DMN and EMN may be more complex than we originally thought 19 .…”

fMRI correlates of jumping-to-conclusions in patients with delusions: Connectivity patterns and effects of metacognitive training

“…However, we observed greater connectivity between PCC (part of the TNN) and the TPN for the draw > conclusion contrast in subjects displaying JTC. We have argued before, based on a previous analysis of healthy participant data from this study ( Andreou et al, 2017a ), that a functional separation (i.e., decreased connectivity) between TPN and TNN is required during evidence gathering to enable the execution of several parallel mental operations. Therefore, increased connectivity between the two systems during evidence gathering in JTC individuals may trigger premature conclusions.…”

“…Another issue not yet addressed in existing patient imaging studies are the complex interactions between brain areas involved in various stages of evidence gathering – a particularly important point, in light of the current trend of neuroimaging literature to focus on the functional integration of brain areas into networks ( Bressler and Menon, 2010 ; Sporns, 2014 ) and the conceptualization of schizophrenia as a ‘dys-connectivity’ disorder ( Andreasen et al, 1998 ; Friston, 1999 ). Our own group ( Andreou et al, 2017a ) has, for example, recently provided evidence suggesting that probabilistic reasoning in healthy individuals is dependent on the connectivity between a task-positive (TPN) and task-negative (TNN) network, of which the former consists of areas typically activated during cognitively demanding tasks, while the latter (also referred to as the default mode network, DMN) includes regions that are commonly deactivated during cognitive processing and show greater activity during rest ( Fox et al, 2005 ; see also the discussion on an intrinsic and an extrinsic mode network in Hugdahl et al, 2015 ). More specifically, we observed that connectivity between the TPN and TNN decreased during evidence gathering, but increased at the moment of arriving to a conclusion ( Andreou et al, 2017a ).…”

“…Our own group ( Andreou et al, 2017a ) has, for example, recently provided evidence suggesting that probabilistic reasoning in healthy individuals is dependent on the connectivity between a task-positive (TPN) and task-negative (TNN) network, of which the former consists of areas typically activated during cognitively demanding tasks, while the latter (also referred to as the default mode network, DMN) includes regions that are commonly deactivated during cognitive processing and show greater activity during rest ( Fox et al, 2005 ; see also the discussion on an intrinsic and an extrinsic mode network in Hugdahl et al, 2015 ). More specifically, we observed that connectivity between the TPN and TNN decreased during evidence gathering, but increased at the moment of arriving to a conclusion ( Andreou et al, 2017a ). Our finding highlights connectivity between these two networks as a further potential factor that may contribute to JTC, which however needs to be confirmed in patients with delusions.…”

Dynamic switching between intrinsic and extrinsic mode networks as demands change from passive to active processing

“…Considering that the default mode network (DMN) in essence is a tasknegative network 2,5,34,35 being up-regulated in periods of absence of specific processing demands, it is an intrinsic mode network. We now propose that the brain alternates between an intrinsic and extrinsic mode of function, corresponding to the dominating environmental demands, with the intrinsic mode network dominating during task-absence, and the extrinsic mode network dominating during task-presence 19,34 . What is new in the present results is that the extrinsic mode network is a task non-specific network, in contrast to task-specific taskpositive networks, like the salience network 10,11,36 , dorsal attention network 3,37 , or central executive network 12,38 .…”