Fig. 3.

A) Architectures of 24 alternative models of somatosensory and fronto-parietal regions, fitted to grand-averaged ERF data. The models differed with respect to the inclusion of a frontal (IFG) and/or parietal (IPC) node, as well as the hierarchical architecture and connections between somatosensory and fronto-parietal areas. B) Contextual modulations of intrinsic connectivity by attention and expectation violation were optimized with respect to 1 null model, 12 bilateral alternative models (attention and expectation violation) and 16 contralateral somatosensory models (expectation violation). In the figure, the contralateral models are shown for left expectation violation. Right expectation violation models were identical but with left lateralization of somatosensory regions. C) Both contralateral S1 and S2 were specified as cortical targets of thalamic input. D) All DCMs were tested using a canonical microcircuit model. Each source was thus modeled as compromising 4 neuronal populations (superficial and deep pyramidal cells, spiny stellate and inhibitory interneurons). E) The winning model structure (M10), identified using fixed-effect Bayesian model selection, included all bilateral regions, with IPC at the highest hierarchical level, as well as connections between S1 to both fronto-parietal nodes and connections between S2 and the frontal node. E) The winning model of connectivity modulation, identified using fixed-effect Bayesian model selection, included changes in gain in bilateral primary, secondary somatosensory cortex, as well as and IFG by attention (M10). Further, the winning model revealed changes in contralateral primary and bilateral secondary somatosensory cortex by expectation violation (M13).