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Giulia Malfatti, Simona Monaco, Guido Barchiesi, Luigi Cattaneo, Luca Turella; Do dorsolateral and dorsomedial pathways interact? Investigating parieto-frontal connectivity during a prehension task: a TMS-fMRI study. . Journal of Vision 2016;16(12):676. doi: https://doi.org/10.1167/16.12.676.
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© ARVO (1962-2015); The Authors (2016-present)
The neural substrates subtending prehension, our ability to reach and grasp objects, comprise two parieto-frontal pathways. The dorsomedial pathway connects the occipito-parietal cortex (superior parieto-occipital cortex, SPOC, and superior parietal lobule, SPL) to the frontal lobe (dorsal premotor area, PMd), while the dorsolateral pathway connects the inferior part of the parietal lobe (anterior intraparietal sulcus, aIPS) with the ventral portion of the precentral gyrus (ventral premotor area, PMv). Both pathways are involved in the planning and execution phase of hand actions, however it is yet unknown whether and how information is transferred within and between these pathways. To answer this question, we adopted a combined approach involving offline 1 Hz repetitive Transcranial Magnetic Stimulation (rTMS) and functional Magnetic Resonance Imaging (fMRI). This approach allows identifying the connectivity profiles in normal conditions and causal modifications induced by offline rTMS. Participants (N=13) performed a grasping movement towards an object while lying in the MR scanner. We manipulated presence or absence of visual feedback and TMS stimulation. We asked participants to keep their eyes either closed (No visual feedback) or open (Visual feedback) when planning and executing the action. Participants performed these tasks after offline 1 Hz rTMS stimulation (Stimulation) or after sham stimulation over the same site (No Stimulation). Offline rTMS was applied over left SPOC as this area is a crucial hub for the fronto-parietal network. Our results showed task-related modulations of connectivity following sham stimulation, suggesting the interplay within and between regions of the two pathways. Furthermore, TMS perturbation over SPOC induced modifications in these connectivity profiles supporting the existence of specific causal interactions between different fronto-parietal regions. Overall, our results suggest that perturbation of one hub of this cortical network induces widespread modifications in both pathways.
Meeting abstract presented at VSS 2016
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