Miriam Acquafredda, Francesco Scarlatti, 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
Vision Science Society meeting 2022
INTRODUCTION: In adult humans, a brief period of monocular deprivation (patching one eye for two hours) induces a form of homeostatic plasticity. Stimuli in the deprived eye are transiently boosted, shifting ocular dominance (e.g., measured with binocular rivalry) and enhancing responses in visual cortex (measured with EEG or fMRI). We asked whether, above and beyond these changes in response amplitude, monocular deprivation also produces a reorganization of visual processing circuits, which we indexed with fMRI functional connectivity. METHODS: Ultra-high field 7T fMRI EPI sequences were acquired in 18 adult normally sighted participants, before and after application of a translucent patch on the dominant eye for two hours. During the acquisitions, a contrast modulated pattern was shown monocularly to the deprived or non-deprived eye and stimulus related activity was regressed out from the fMRI timeseries; in separate sessions, fMRI signals were also recorded in resting state conditions. We analyzed the correlations of the fMRI signal between a priori defined cortical and subcortical regions of interest. Primary visual cortex V1 was used as “seed” area, from which we extracted a reference timeseries and correlated it with timeseries from the other areas to give an index of functional connectivity. RESULTS: After monocular deprivation, V1 increased its functional connectivity with a set of regions primarily located in the ventral visual stream, but also including motor and somatosensory areas. V1 functional connectivity with the lateral geniculate nucleus, its main thalamic input, was unaffected by deprivation. In contrast, a selective post-deprivation increase in functional connectivity was observed for the adjacent ventral pulvinar. CONCLUSIONS: These results suggest that the effects of short-term monocular deprivation involve a transient reorganization of cortical circuits, including both local circuits and long-range projections. They also suggest that ventral pulvinar plays an important and previously unappreciated role in sustaining visual plasticity through adulthood. Acknowledgements European Research Council (ERC): European Union’s Horizon 2020 research and innovation program, grant n. 801715 (PUPILTRAITS) and n. 832813 (GenPercept). Italian Ministry of University and Research: PRIN2017 program (grant n. 2017HMH8FA and n. 2017SBCPZY) and FARE-2 (grant SMILY).