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bioRxiv · 10.1101/2020.03.18.997031

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

Riemer, F.·Gruener, R.·Beresniewicz, J.·Kazimierczak, K.·Ersland, L.·Hugdahl, K.
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Abstract

We here report on the relationship between default and extrinsic mode networks across alternating brief periods of rest and active task processing. We used three different visual tasks: mental rotation, working memory and mental arithmetic in a classic fMRI ON-OFF block design where task (ON) blocks alternated with equal periods of rest (OFF) blocks. By analysing data in two ways, using an ON-OFF contrast, we showed the existence of a generalized task-positive network, labelled the extrinsic mode network (EMN) which was anti-correlated with the default mode network (DMN) as processing demands shifted from rest to active processing. We then identified two key regions of interest (ROIs) in the SMA and Precuneus/PCC regions as hubs for the extrinsic and intrinsic networks, and extracted the time-course from these ROIs. The results showed a close to perfect correlations for the SMA and Precuneus/PCC time-courses for ON-respective OFF-blocks. We suggest the existence of two large-scale networks, an extrinsic mode network and an intrinsic mode network, respectively, which are up- and down-regulated as environmental demands change from active to passive processing.

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Riemer, F., Gruener, R., Beresniewicz, J., Kazimierczak, K., Ersland, L., Hugdahl, K.. 2020-03-18. Dynamic switching between intrinsic and extrinsic mode networks as demands change from passive to active processing. https://doi.org/10.1101/2020.03.18.997031

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