Mapping Of Sensory Network Plasticity In The Blind And Its Associated Gene Expression

Purpose: Early evidences indicate that the visual areas are functionally recruited in processing non-visual sensory information after visual deprivation.However,the signal transmission mechanisms between the visual and non-visual sensory areas and their molecular basis are still unknown.In this study,a fine-scale voxel-wise resting-state functional connectivity analysis was applied to map the connectivity reorganization within the visual areas and between the visual and auditory/somatosensory areas in the blind with different onset ages of blindness.It has been suggested that the maturation and experience-dependent synaptic plasticity of the visual cortex are modulated by genetic factors.We tried to identify more genes that are associated with the connectivity reorganization of the sensory cortex.Materials and Methods: We recruited 31 congenitally blind(CB),34 early blind(EB),38 late blind(LB),and 40 sighted controls(SC)in this study.Resting-state functional MRI(rs-f MRI)data and three-dimensional T1 weighted images were acquired using 3.0T MRI scanner.After data preprocessing,we employed a fine-scale voxel-wise analysis method that compared every link between each pair of the voxels to explore the FC group differences.We then categorized the visual voxels according to their FC alteration patterns after visual deprivation.Finally,spatial correlation analyses were carried out to identify the relationship between FC reorganization and structural changes as well as gene expression.Results: Compared to the sighted controls,all blind individuals demonstrated increased inter-modal connectivity between the dorsal visual area and the auditory/somatosensory association areas,and increased intra-modal connectivity within the visual cortex,indicating an indirect cortico-cortical pathway that may transmit signals from the non-visual sensory areas to the visual areas in the blind.The connectivity reorganization patterns of the visual cortex revealed the coexistence of the increased and decreased connectivity in the same visual area,suggesting more extensive connectivity reorganization in the blind than previously known.The positive correlation between the connectivity and gray matter volume changes in the sensory cortices in the blind individuals denoted a structural basis for the connectivity changes.The significant correlations between the onset age of blindness and the intraand inter-modal connectivity emphasized the importance of the sensory experience in the critical developmental period in the functional organization of the sensory areas.However,the very similar connectivity reorganization patterns in the blind subgroups indicated the important contribution of the sensory experience after the critical developmental period to the connectivity reorganization after visual deprivation.The spatial correlation analysis between the connectivity reorganization and the genome-wide gene expression profiles revealed hundreds of genes that were associated with the connectivity reorganization in the blind.These genes were enriched in the cortical neurons and in the biological processes of the chemical synaptic transmission,ion transport,nervous system development,and G-protein coupled and glutamate receptor signaling.Conclusion: In this study,we mapped the topological feature of the connectivity reorganization in the sensory areas in the blind.All blind individuals showed both increased and decreased connectivity between the visual-nonvisual sensory areas and within the visual areas.Besides,the lifetime sensory experience could induce the connectivity plasticity in the blind.Several molecular processes were also found to be associated with the connectivity reorganization after visual deprivation.