The masks of visual areas used in the study.

The masks of Brodmann areas 17 (primary visual cortex, red), 18 (secondary visual cortex, green), and 19 (associative visual cortex, blue) are presented on the inflated reconstruction of participants’ averaged cortical anatomy.

The visual cortex in blind and sighted individuals represents differences between individual concrete words.

The results of cross-modal classification of activation patterns for individual words, presented in the spoken and the written modality, in the visual areas of blind and sighted participants. * p < 0.05, ** p < 0.01, corrected for multiple comparisons using the false discovery rate. Error bars represent the standard error of the mean. The black line indicates the chance classification level.

The activation patterns in the visual cortex of blind and sighted individuals reflect physical, but not conceptual similarity between word referents.

Correlations between the neural similarity matrices, reflecting similarity between the activation patterns for individuals words in the visual areas of blind and sighted participants, and the behavioral ratings of physical and conceptual similarity between the word referents. * p < 0.05, ** p < 0.01, corrected for multiple comparisons using the false discovery rate. Error bars represent the standard error of the mean.

Between-group similarity in activity patterns for words in the visual areas of blind and sighted participants is comparable to within-group similarities.

The between-group similarity scores were calculated by correlating the neural similarity matrices of each participant, reflecting similarity between the activity patterns for specific words in the visual areas, with the neural similarity matrices of every participant in the other group (blind-sighted, sighted-blind). The within-group similarity scores were calculated by correlating the neural similarity matrices of each participant with the neural similarity matrices of every other participant from a given group (blind-blind, sighted-sighted). ** p < 0.01, corrected for multiple comparisons using the false discovery rate. Error bars represent the standard error of the mean.

During word processing, the visual cortex in both blind and sighted participants shows the greatest “representational connectivity” to the occipitotemporal cortex.

For each brain region, the representational connectivity to the visual cortex was calculated by correlating neural similarity matrices, reflecting similarity between the activity patterns for specific words, obtained for the visual cortex and this region. In each participant group, the average correlation between the visual cortex and the target brain regions was subtracted from the results, to visualize regions that show higher-than-average and lower-than-average representational connectivity to the visual cortex during the word processing. The results for such regions are marked in blue (comparison against average correlation, p < 0.05, corrected for multiple comparisons using the false discovery rate). The target brain regions were sorted by the obtained representational connectivity scores. Error bars represent the standard error of the mean.

Searchlight analysis.

(A-B) The results of correlation between the neural similarity matrices, reflecting similarity between the activity patterns for specific words, and the behavioral ratings of (A) physical and (B) conceptual similarity between the word referents. (C) Brain regions in which the correlations with physical similarity ratings were significantly higher than the correlations with conceptual similarity ratings. The white arrow points to the effect in the occipitotemporal cortex. The analyses combined blind and sighted participants in one sample, to achieve the greatest statistical power to detect common effects. Between-group comparisons did not produce significant results. In all analyses, The statistical significance was determined using threshold-free cluster enhancement (TFCE) maps and Monte Carlo simulation. The statistical threshold was set at p < 0.05, corrected for multiple comparisons. The T-values for the effects that survived the threshold are presented for the visualization purposes.

Univariate analysis of activations in the visual cortex.

The average activations for spoken and written words, compared to rest periods, in the visual areas of blind and sighted participants. * p < 0.05, ** p < 0.01, corrected for multiple comparisons using the false discovery rate. Error bars represent the standard error of the mean.

English translations of the questions used in the fMRI experiment.

The behavioral ratings of physical and conceptual similarity between the referents of words used in the study.

The matrices visualize ratings for all 190 word pairs that can be created from the 20 words used in the study. The participants rated the similarity between word referents on scales from 1 to 5. The scores were averaged across the participants (there were no average scores greater than 4). The English translations of Polish words that were actually used in the study are presented.

The activity patterns in the visual cortex of blind and sighted individuals reflect physical, but not conceptual similarity between word referents – analysis in the left hemisphere only.

The results of correlation between the neural similarity matrices, reflecting similarity between the activity patterns for specific words in the visual areas of blind and sighted participants, and the behavioral ratings of physical and conceptual similarity between the word referents. Only activity patterns in the left hemisphere were analyzed. * p < 0.05, ** p < 0.01, corrected for multiple comparisons using the false discovery rate. Error bars represent the standard error of the mean.

The activity patterns in the left anterior lobe reflect conceptual similarity between word referents in both participant groups.

The results of correlation between the neural similarity matrices, reflecting similarity between the activity patterns for specific words in the left anterior temporal lobe (ATL, marked in purple) of blind and sighted participants, and the behavioral ratings of physical and conceptual similarity between the word referents. * p < 0.05, corrected for multiple comparisons using the false discovery rate. Error bars represent the standard error of the mean.

During the word processing, the visual cortex in both blind and sighted participants shows the greatest “representational connectivity” to the occipitotemporal cortex - the analysis constrained to the primary visual cortex (BA 17).

For each brain region, the representational connectivity to the BA 17 was calculated by correlating neural similarity matrices, reflecting similarity between the activity patterns for specific words, obtained for the BA 17 and this region. In each participant group, the average correlation between the BA 17 and the target brain regions was subtracted from the results, to visualize regions that show higher-than-average and lower-than-average representational connectivity to the BA 17 during the word processing. The results for such regions are marked in blue (comparison against average correlation, p < 0.05, corrected for multiple comparisons using the false discovery rate). The target brain regions were sorted by the obtained representational connectivity scores. Error bars represent the standard error of the mean.

During the word processing, the visual cortex in both blind and sighted participants shows the greatest “representational connectivity” to the occipitotemporal cortex - the analysis constrained to the secondary visual cortex (BA 18).

For each brain region, the representational connectivity to the BA 18 was calculated by correlating neural similarity matrices, reflecting similarity between the activity patterns for specific words, obtained for the BA 18 and this region. In each participant group, the average correlation between the BA 18 and the target brain regions was subtracted from the results, to visualize regions that show higher-than-average and lower-than-average representational connectivity to the BA 18 during the word processing. The results for such regions are marked in blue (comparison against average correlation, p < 0.05, corrected for multiple comparisons using the false discovery rate). The target brain regions were sorted by the obtained representational connectivity scores. Error bars represent the standard error of the mean.

Searchlight analysis - results presented for each group separately.

(A-B) The results of correlation between the neural similarity matrices, reflecting similarity between the activity patterns for specific words, and the behavioral ratings of physical similarity between the word referents (A) in the blind participants and (B) in the sighted participants. (C) Analogous analysis including the ratings of conceptual similarity between the word referents. The results for the sighted participants are presented. No significant results in the blind group were found. The statistical significance was determined using threshold-free cluster enhancement (TFCE) maps and Monte Carlo simulation. The statistical threshold was set at p < 0.05, corrected for multiple comparisons. The T-values for the effects that survived the threshold are presented for the visualization purposes.

Whole-brain univariate analysis: activations for words relative to rest periods.

Activations for spoken and written words, compared to rest, in the blind and the sighted group. The written words were presented in the Braille alphabet in the blind group and in the visual alphabet in the sighted group. As indicated by the font colors in the titles of the figure panels, warm colors indicate stronger activations for words, whereas cold colors indicate stronger activations for rest periods (i.e., deactivations during the processing of words). The statistical threshold was set at p < 0.001, corrected for multiple comparisons using surface patch extent.

Whole-brain univariate analysis: comparisons between groups and sensory modalities of word presentations.

The font colors in the titles of the figure panels match groups or conditions with warm and cold colors in the figure. The statistical threshold was set at p < 0.001, corrected for multiple comparisons using surface patch extent.

Correlation of activity patterns for words in the visual areas with behavioral similarity ratings: investigating effects of modality of word presentation.

The results of correlation between the neural similarity matrices, reflecting similarity between the activity patterns for specific words in the visual areas of blind and sighted participants, and the behavioral ratings of physical (upper panels) and conceptual (bottom panels) similarity between the word referents. The analysis was run separately for runs in which words were presented in the spoken modality (blue bars) and in the written modality (orange bars). The written words were presented in the Braille alphabet in the blind group and in the visual alphabet in the sighted group. * p < 0.05, ** p < 0.01, corrected for multiple comparisons using the false discovery rate. Error bars represent the standard error of the mean.