Dynamics of directed information transfer in visual processes

G Plomp1, A Hervais-Adelman2, L Astolfi3, C Michel4

1Department of Basic Neurosciences, University of Geneva, Switzerland
2Brain and Language Lab, University of Geneva, Switzerland
3Department of Computer, Control, and Management, University of Rome, Italy
4Functional Brain Mapping Lab, University of Geneva, Switzerland
Contact: gijs.plomp@unige.ch

Visual stimuli quickly evoke processing in a network of primary visual and higher-level brain areas, giving rise to dynamic interactions between them that are poorly understood. Here we investigated directed interactions in visual processing via time-varying Granger-causal modeling. Using fMRI we localized in each subject six regions of interest (ROI) in each hemisphere: primary visual cortex, lateral occipital complex, fusiform gyrus, area MT+, lateral intraparietal sulcus and the frontal eye field. In a separate EEG session subjects performed a target detection task on the center of the screen while we briefly presented checkerboards in the lower left and right visual field. From the EEG we estimated time-series of activity in each ROI using a distributed linear inverse solution (WMN) and realistic individual head-models. With adaptive MVAR modeling we then derived the directed influence between all ROIs in time, scaled by the instantaneous spectral power (wPDC). The results show peak driving from primary visual cortex at expected latencies and strong early influences from parietal areas onto primary visual cortex. The work demonstrates the potential for studying dynamic relationships between bottom-up and top-down visual processes by combining EEG source imaging and wPDC.

Up Home