Miriam Acquafredda, Laura Biagi, Michela Tosetti, Maria Concetta Morrone, Paola Binda
Short-term monocular deprivation in adult humans alters functional brain connectivity measured with ultra-high field Magnetic Resonance Imaging
XIII Congresso Nazionale AIRMM
In adult humans, a brief period (2 hours) of monocular deprivation induces a form of homeostatic plasticity. Stimuli in the deprived eye are transiently boosted, shifting perceptual ocular dominance and enhancing evoked fMRI responses in the visual cortex and in the ventral pulvinar, though not in the lateral geniculate nucleus (LGN). We asked whether, above and beyond these changes in cortical response, monocular deprivation also produces a functional reorganization of visual processing circuits. Ultra-high field 7T fMRI EPI resting-state sequences (with two TRs, 3000 and 1000 ms) were acquired in 20 normally sighted adult participants, before and after the application of a translucent patch on the dominant eye for two hours. During the acquisitions, participants were laying in the scanner with their eyes closed. Functional connectivity was measured by correlating BOLD signals in each cortical voxel with those in subcortical “seed” area (ventral pulvinar or LGN) after filtering and nuisance regression. Using Granger causality, we estimated the directionality of functional connectivity with V1, which was distinct for LGN and ventral pulvinar, and compatible with the role of pulvinar in supporting cortico-cortical loops. Comparing functional connectivity before and after monocular deprivation, we found decreased connectivity of early visual areas (V1-V3) with the ventral pulvinar, but unchanged connectivity with LGN. These results suggest that the ventral pulvinar plays an important and previously unappreciated role in sustaining visual plasticity throughout adulthood, possibly by orchestrating the circuit of cortico-cortical connections that may implement the homeostatic regulation of neural function.