Congenital blindness has been shown to result in behavioral adaptation and neuronal reorganization, but the underlying neuronal mechanisms are largely unknown. Brain rhythms are characteristic for anatomically defined brain regions and provide a putative mechanistic link to cognitive processes. In a novel approach, using magnetoencephalography resting state data of congenitally blind and sighted humans, deprivation-related changes in spectral profiles were mapped to the cortex using clustering and classification procedures. Altered spectral profiles in visual areas suggest changes in visual alpha-gamma band inhibitory-excitatory circuits. Remarkably, spectral profiles were also altered in auditory and right frontal areas showing increased power in theta-to-beta frequency bands in blind compared with sighted individuals, possibly related to adaptive auditory and higher cognitive processing. Moreover, occipital alpha correlated with microstructural white matter properties extending bilaterally across posterior parts of the brain. We provide evidence that visual deprivation selectively modulates spectral profiles, possibly reflecting structural and functional adaptation.
Data-Driven Classification of Spectral Profiles Reveals Brain Region-Specific Plasticity in Blindness
Cross-group comparison. (A) Histogram of classification ranks. Bin width is 1. (B) The topographic distribution of significantly different classification ranks in the cross-group classification is highlighted in red, as tested by a permutation procedure. (C) The normalization spectrum used in the normalization procedure (i.e., the average power spectrum across segments and voxels) is displayed, averaged across participants, separately for each experimental group (upper panel). Shaded error bars reflect the standard error of the mean across participants. Frequency is displayed at the x-axis, scaled logarithmically from 1 to 120 Hz; power on the y-axis. For visualization, power was interpolated at 50 Hz to remove line noise. In order to test the impact of the normalization procedure on our cross-group classification findings, a control analysis on the nonnormalized data was performed (lower panel). Confirming our findings, the control analysis revealed significant findings in various areas overlapping with the areas observed in the main analysis (highlighted in dark red). However, we also observed several additional areas with significant group differences (highlighted in light pink), as well as areas that, in contrast to the main analysis, did not show significant group differences in the control analysis (see Supplementary Table 2 for a full list). Only findings at brain areas that showed group differences in both the main cross-group and the control analyses (i.e., with and without normalization procedure) will be considered for discussion.
Max Planck Institute for Empirical Aesthetics
